[
    {
        "id": 1,
        "chunk": "# Antifogging/Antibacterial Coatings Constructed by N‑Hydroxyethylacrylamide and Quaternary Ammonium-Containing Copolymers  \n\nShan Bai, Xiaohui Li,\\* Yunhui Zhao, Lixia Ren, and Xiaoyan Yuan\\*  \n\nCite This: ACS Appl. Mater. Interfaces 2020, 12, 12305−12316",
        "category": " References"
    },
    {
        "id": 2,
        "chunk": "# ACCESS  \n\nE Metrics & More  \n\nSupporting Information  \n\n![](images/ba55c7b861b6b000bdb486f6f78e545cfa1f23b9cd4f78965429d8af6233d48d.jpg)  \n园 Article Recommendations  \n\nABSTRACT: Endoscopic surgery has gained widespread applications in various clinical departments, and endoscope surfaces with antifogging and antibacterial properties are essential for elaborate procedures. In this work, novel antifogging/antibacterial coatings were developed from a cationic copolymer and a hydrophilic copolymer, polyhedral oligomeric silsesquioxane-poly(quaternary ammonium compound-co-2-aminoethyl methacrylate hydrochloride) [POSS-P(QAC-co-AEMA)] and poly( $\\mathrm{\\Delta}N$ -hydroxyethylacrylamide-co-glycidyl methacrylate) [P(HEAA-co-GMA)] via a facile and green blending method. Such transparent coatings showed excellent antifogging performance under both in vitro and in vivo fogging conditions, mainly attributed to the high water-absorbing capability of HEAA and QAC. Antibacterial assays proved that the blending coatings had a superior antibacterial property, which could be improved with the proportion of POSS-P(QAC-co-AEMA) because of the bactericidal efficiency of cationic QAC. Meanwhile, owing to the high hydratability of HEAA, the blending coatings exhibited a bacteria-repelling property. By simply tuning the blending ratio of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA), the comprehensive bacteria-killing and bacteria-repelling properties of the coatings were achieved. Moreover, after incubating with red blood cells, the prepared blending coatings presented a lower hemolytic rate of less than $5\\%$ . The findings provided a potential means for addressing the challenge of fogging and bacterial contamination occurring in endoscopic lenses and other medical devices.  \n\nKEYWORDS: antifogging coatings, antibacterial properties, quaternary ammonium compounds, N-hydroxyethylacrylamide, enhanced hydration",
        "category": " Abstract"
    },
    {
        "id": 3,
        "chunk": "# INTRODUCTION  \n\nOver the past decade, endoscopic surgery has been widely accepted as a minimally invasive approach and applied in various clinical departments because it has a precise small-cut and rapid recovery characteristics as compared with open surgery.1 During a safe and successful endoscopic procedure such as laparoscopy and colonoscopy, maintaining a clear vision is paramount, which can improve precision, reduce operative time, and even prevent inadvertent injury. Meanwhile, microbial colonization and biofilm formation on the surfaces of endoscopes is another impediment for a safe surgery.3−5  \n\nThe main reason of optical loss is endoscopic lens fogging, which is caused by the discrepancies in temperature and humidity between ambient conditions and in vivo.2 Most antifogging approaches for medical devices are based on traditional methods, for instance, spraying antifogging reagents or employing heating apparatus, but they show disadvantages of short residual action, cumbersome procedure, high medical expenses, and so on.6,7 Currently, developing coating surfaces with enhanced antifogging performance has been gaining much attention to solve the atomization problem.8−19 In addition to superhydrophilic and superhydrophobic strategies, applying a water-absorbing coating with amphiphilicity to a surface is an effective antifogging approach, where the condensed water molecules or the moist vapor can be rapidly imbibed into the bulk of the coating, followed by uniform diffusion of the absorbed water molecules to prevent the formation of a large and light-scattering water domain.8−14,20−23  \n\n![](images/411e11998af045cf8c9e04cabff9ffc93914638a33c5db847e428a5e42d48883.jpg)  \nFigure 1. (A) Synthesis of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA) copolymers. (B) Schematic preparation of the blending coatings.  \n\nAs invasive medical devices, endoscopes are prone to be heavily contaminated and associated with the healthcareassociated infections. On one hand, it is inevitable for endoscopes to be contaminated by environmental bacteria during storage, and the endoscopic environments provide favorable conditions for bacterial proliferation and subsequent biofilm formation.24,25 In addition, clinically used endoscopes comprise a high bioburden of microbes that originate from patients, and it is difficult to clean and disinfect the used devices due to their complex and delicate structure.26 Therefore, a dual-functional antifogging/antibacterial surface is in high demand in the field of endoscopy to prevent fogging and bacterial contamination.  \n\nIn recent years, comprehensive antibacterial coatings have been broadly developed to solve the problems of microbial infections in medical device surfaces.27−33 Nevertheless, only a few studies have focused on the development of antifogging and antibacterial surfaces so far.16,34−37 For instance, robust poly(vinyl alcohol)/poly(acrylic acid)/silver composite films with antifogging and antibacterial properties were prepared, where the abundant hydroxyl groups in the polymers could prevent fog formation and distributed silver nanoparticles endowed the composite films with bactericidal activity.34 Zhang et al. fabricated a multifunctional coating for antifogging, self-cleaning, and antimicrobial properties on the basis of zwitterionic peptides. The superhydrophilicity of zwitterionic material could strongly bind to water molecules and thus impart the coating with excellent antifogging performance and resistance to bacterial adhesion.16 However, the antibacterial properties of these prepared antifogging/ antibacterial surfaces were achieved by either an active-attack bacteria-killing or a passive-defense bacteria-repelling mechanism. Despite their general effectiveness, both the surfaces have inherent limitations for practical applications. Bacteria would grow rapidly and form a stubborn biofilm once attached onto the passive-defense surfaces, whereas for the active-attack bacteria-killing surfaces, continuous contamination of dead bacteria and debris is the fatal weakness, which causes the bactericidal groups to be shielded and thus greatly reduces the killing efficiency.38,39  \n\nQuaternary ammonium compounds (QACs) display broadspectrum bactericidal activity by destructive interaction with the cell membrane and subsequent enzyme inactivation, and fhoaovde ibnedeunstarpyp, iwedasitnewmataenrytreladtsmseunct,hansdbisomoend.i4c0a−l43maAtemrioanlsg, them, (meth)acrylic derivatives-related QACs are generally employed as antibacterial materials. A series of alkyl bromides with different alkyl chain lengths were used to quaternize poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), and the results suggested that PDMAEMA quaternized with 1-bromobutane (PDMAEMA-C4) exhibited balanced membrane-disrupting activity and biocompatibility.44,45 Owing to two hydrogen-bond donors of amide groups and hydroxyl groups in $N.$ -(2-hydroxyethyl)acrylamide (HEAA), (polyHEAA)-based materials exhibit strong resistance to bacterial attachment, protein nonspecific adsorption, and cell adhesion.46−49 The hydration ability of a copolymer can be enhanced by incorporation of HEAA. Additionally, it was reported that hydroxyl groups are instrumental in improving the hemocompatibility of cationic polymers.50  \n\nIn this study, the dual-functional antifogging/antibacterial coatings that combine bacteria-killing and bacteria-repelling abilities were developed by blending polyhedral oligomeric silsesquioxane-poly(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylbutan ammonium bromide-co-2-aminoethyl methacrylate hydrochloride) [POSS-P(QAC-co-AEMA)] and poly(N-hydroxyethyl acrylamide-co-glycidyl methacrylate) [P(HEAA-coGMA)]. Incorporation of AEMA and GMA was performed to crosslink the two random copolymers, and a small quantity of 1,3,5-triformylbenzene (TFB) was added as a co-crosslinker to further react with the amino and hydroxyl groups in the copolymers as well as amino-modified glass substrates, forming a chemically crosslinked stable system. Hydrophobic POSS was introduced to facilitate coating stability and mechanical properties.11,51,52 The antifogging and antibacterial properties of the blending coatings with different blending ratios were evaluated by hot-vapor and cold-warm antifogging tests, standard plate count method, bacterial antiadhesive assays, and growth inhibition to acquire the optimized blending ratios.  \n\nTable 1. Compositions and Number-Average Molecular Weights of the Synthesized Copolymers   \n\n\n<html><body><table><tr><td rowspan=\"2\"></td><td colspan=\"2\">feeding ratio (mol/mol)</td><td colspan=\"2\">actual ratioa (mol/mol)</td><td colspan=\"2\">molar compositionb (mol/mol)</td><td rowspan=\"2\">Mnc (x104)</td><td rowspan=\"2\">Dc</td></tr><tr><td>copolymer QAC/AEMA</td><td>HEAA/GMA</td><td>QAC/AEMA</td><td>HEAA/GMA</td><td>QAC/AEMA</td><td>HEAA/GMA</td></tr><tr><td>POSS-P(QAC-co-AEMA)</td><td>200:50</td><td></td><td>3.03:1</td><td></td><td>342:113</td><td></td><td>12.0</td><td>1.32</td></tr><tr><td>P(HEAA-co-GMA)</td><td></td><td>300:20</td><td></td><td>14.28:1</td><td></td><td>795:55.7</td><td>9.94</td><td>1.24</td></tr></table></body></html>\n\naDetermined by $^1\\mathrm{H}$ NMR spectra. bCalculated by the GPC results and actual molar ratios. cObtained from GPC using poly(ethylene glycol) as the standard.  \n\nTable 2. Compositions for Preparation of the Antifogging/Antibacterial Coatings   \n\n\n<html><body><table><tr><td>coating</td><td>POSS-P(QAC-co-AEMA) (mg)</td><td>P(HEAA-co-GMA) (mg)</td><td> TFB (mg)</td><td> POSS-P(QAC-co-AEMA)/P(HEAA-co-GMA) mass ratio (mg/mg)</td></tr><tr><td>PPQAa</td><td>18</td><td>0</td><td>0.54</td><td>1:0</td></tr><tr><td>PPQA/PHGb</td><td>12</td><td>6</td><td>0.54</td><td>1:0.5</td></tr><tr><td>PPQA/PHGb</td><td>9</td><td>9</td><td>0.54</td><td>1:1</td></tr><tr><td>PPQA/PHGb</td><td>6</td><td>12</td><td>0.54</td><td>1:2</td></tr><tr><td>PHGa</td><td>0</td><td>18</td><td>0.54</td><td>0:1</td></tr></table></body></html>\n\naOne-component coatings were prepared from POSS-P(QAC-co-AEMA) or P(HEAA-co-GMA) only. bBlending coatings were prepared from POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA) with different mass ratios.  \n\nAdditionally, antifogging is considered as the principal intention in vivo.",
        "category": " Introduction"
    },
    {
        "id": 4,
        "chunk": "# EXPERIMENTAL SECTION  \n\nSynthesis of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA) Copolymers. As shown in Figure 1A, the QAC and $N_{\\sun}$ - hydroxyethylacrylamide (HEAA)-containing copolymers, that is, POSS-P(QAC- $c o$ -AEMA) and P(HEAA- $_{c o}$ -GMA), for the blending coating preparation were synthesized via reversible addition− fragmentation chain transfer (RAFT) polymerization and free radical polymerization, respectively. QAC was prepared by quaternization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) with 1-bromobutane. The hydrophobic component was incorporated by modifying the RAFT agent of CPADB with aminopropylisobutyl polyhedral oligomeric silsesquioxane $\\left(\\mathrm{POSS-NH}_{2}\\right)$ ) to obtain POSS-CPADB.53 Compositions and molecular weights of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA) copolymers are given in Table 1. It is worth mentioning that the copolymer compositions obtained by combining gel permeation chromatography (GPC) results with actual molar ratios were higher than their feeding, probably due to the copolymer aggregating in the eluent when determining molecular weight by GPC. Detailed synthesis procedures and the characterizations of their chemical structure by proton nuclear magnetic resonance $\\mathrm{\\Omega^{\\prime1}H\\ N M R})$ spectroscopy and GPC are described in the Supporting Information and Figure S1.  \n\nPreparation of the Blending Coatings. The preparation process of the blending coatings is schematically illustrated in Figure 1B. Bare glass was first treated with oxygen plasma (18 W, $^{60\\mathrm{~s},}$ Harrick Plasma PDC-32G-2, USA) to produce abundant hydroxyl groups, followed by immersing into (3-aminopropyl)- trimethoxysilane/methanol solution $(5\\%,{\\bf v}/{\\bf v})$ for $^{4\\mathrm{~h~}}$ and sonicating with methanol and ethanol in sequence to provide amino-functionalized surfaces. The successful surface modifications were demonstrated by the change of the water contact angle (WCA) for each surface as also presented in Figure 1B. Then, copolymers with various POSS-P(QAC-co-AEMA)/P(HEAA-co-GMA) blending mass ratios and a certain amount of TFB (Table 2) were dissolved in $200~\\mu\\mathrm{L}$ of ethanol (P(HEAA-co-GMA) stored in aqueous solution with a concentration of $60~\\mathrm{mg/mL}$ ). A determined volume of the mixture was drop-coated onto the modified glass slides to allow the crosslinking of POSS-P(QAC-co-AEMA), P(HEAA-co-GMA), and TFB for antifogging tests. It was also cast onto a cropped square glass in $1\\times1~\\mathrm{cm}^{2}$ for antibacterial and hemolytic analysis. All coated samples were dried at room temperature and subsequently thermalcured at $40~^{\\circ}\\mathrm{C}$ overnight. The resultant coatings with different blending ratios were denoted as PPQA, $\\mathrm{PPQA_{2}/P H G_{1}},$ $\\mathrm{PPQA_{1}/}$ $\\mathrm{PHG}_{\\mathrm{1}},$ $\\mathrm{\\bar{PPQA}_{1}/P H G}_{2},$ and PHG, which showed the thicknesses of  \n\n$9.14\\pm0.39\\$ , $7.34\\pm0.36,$ $7.57\\pm0.59.$ , $7.13\\pm0.22,$ and $6.74\\pm0.17$ $\\mu\\mathrm{m},$ respectively (Figure S2). Overall, a green blending strategy, where water and ethanol were employed as solvents, was developed to prepare the dual-functional coatings with desired antifogging and antibacterial properties.54  \n\nCharacterizations of the Blending Coatings. The mean WCA, droplet diameter $(D)_{\\cdot}$ , and their evolution within $400\\mathrm{~s~}$ were recorded on a contact angle meter (Shanghai Zhongchen Instrument JC2000D, China) at room temperature. Each coating was analyzed at least three times. Variation of the wetted surface area (S) for various coatings was further calculated by the following equation  \n\n$$\n\\Delta S/S_{0}=\\frac{S_{(t)}-S_{0}}{S_{0}}=\\frac{\\pi{D_{(t)}}^{2}/4-S_{0}}{S_{0}}\n$$  \n\nwhere $D_{(t)}$ and $S_{(t)}$ are defined as the droplet diameter and wetted surface area at a given time, respectively. $S_{0}$ is the original wetted surface area. Attenuated total reflectance−Fourier transform infrared spectroscopy (ATR−FTIR) (TENSO 27 spectrometer, Germany) was employed to confirm the chemical structure of the blending coatings. To test transparency and quantitively determine the antifogging properties of the coatings, visible light transmittance values of the double-coated surfaces were collected on a $722\\ s$ visible spectrophotometer (Shanghai Jinghua Technology Instruments, China) in the wavelength range of $400{-}800\\ \\mathrm{nm}$ before and after the samples were placed at $-20\\ ^{\\circ}\\mathrm{C}$ for $30~\\mathrm{\\min}$ . The surface morphology and root-mean-square roughness $(R_{\\mathrm{q}})$ values of the prepared coatings were observed by atomic force microscopy (AFM) (Benyuan Nano-Instruments CSPM5500A, China).  \n\nAntifogging Tests. Glass substrates were coated with a copolymer coating on both sides. To perform the antifogging tests in vitro, the samples were held ${\\mathfrak{s}}\\mathrm{cm}$ above hot water $(80~^{\\circ}\\dot{\\mathrm{C}})$ for $10~\\mathsf{s}$ and in a refrigerator $(-20\\ ^{\\circ}\\mathrm{C})$ for $30~\\mathrm{min}$ with the purpose of hotvapor and cold-warm antifogging tests, respectively, followed by moving the samples to ambient conditions and taking photographs immediately.  \n\nTo further assess the antifogging performance in vivo, a rabbit oral cavity with a digital endoscope (Hangzhou Jingjiying Hardware Store, China) was used as the animal model. All procedures involving animals comply with the Tianjin Experimental Animal Management Ordinance, China. The circular coating sample with a diameter of 4.9 mm was first prepared and fixed between the endoscope lens and its protective sleeve. Then, the structural component of the digital endoscope was placed into the rabbit’s oral cavity and maintained for a certain time. The process was recorded from endoscope insertion onward.  \n\nAntibacterial Tests. Minimum inhibitory concentrations (MIC) of the synthesized copolymers were first determined. Typically, 4096 $\\mu\\mathrm{g}$ of the copolymer was first dissolved in $2~\\mathrm{mL}$ of sterile phosphate buffered saline (PBS) and then diluted with the serial two-fold method to obtain a series of copolymer solutions with varying concentrations. The copolymer solution $(100~\\mu\\mathrm{L})$ with a certain concentration and $100\\mu\\mathrm{L}$ of bacterial suspension $(3\\times10^{5}\\mathrm{CFU/mL})$ ) were added into each well. The bacterial suspension with equal volume of sterile PBS was set as the positive control and $100~\\mu\\mathrm{L}$ of pure Mueller−Hinton broth (MHB) diluted with $100~\\mu\\mathrm{L}$ of sterile PBS buffer was used as the negative control. After incubating the plate at $37^{\\circ}\\mathrm{C}$ at the speed of $80\\ \\mathrm{rpm}$ for $^{24\\mathrm{h},}$ the optical density (OD) at $600\\mathrm{nm}$ of the microorganism solutions was recorded. The MIC value was defined as the lowest concentration of copolymer, where no visual growth of bacteria was found. The bacterial growth inhibition rate was determined according to eq 2  \n\n![](images/e6fa0cc81b80f468dbd3c41d00ee54d7e600daa4b9363a031eb4108fa9ca0524.jpg)  \nFigure 2. (A) ATR−FTIR spectra of the prepared copolymer coatings. (B) Transmittance curves of the double-coated samples and bare glass in the wavelength range of $400{-}800~\\mathrm{nm}$ . (C) AFM topographic images and root-mean-square $(R_{\\mathrm{q}})$ roughness of the coatings over a scope of $4\\times4$ $\\mu\\mathrm{m}^{2}$ with the tapping mode.  \n\n$$\n=\\frac{O D_{\\mathrm{positive\\control}}-O D_{\\mathrm{sample}}}{O D_{\\mathrm{positive\\control}}-O D_{\\mathrm{negative\\control}}}\\times100\n$$  \n\nFor the coating samples, the antibacterial activities were estimated by the standard plate count method. The test coatings sterilized in ultraviolet before the test were placed into a 24-well plate, followed by adding the bacterial suspension $(200~\\mu\\mathrm{L},~3~\\times~10^{\\bar{4}}~\\mathrm{CFU/mL})$ and MHB $(600\\mu\\mathrm{L})$ . After culturing for $^{24\\mathrm{h},}$ , the bacterial suspension was diluted with an appropriate factor and $10\\mu\\mathrm{L}$ of the diluted suspension was spread on nutrient agar. A sample of bare glass was the positive control. The bacterial colonies were photographed, and the colony numbers $(N)$ were counted after overnight incubation. The bacterial growth inhibition rate was calculated from eq 3  \n\n$$\n(\\%)=\\frac{N_{\\mathrm{positive\\control}}-N_{\\mathrm{sample}}}{N_{\\mathrm{positive\\control}}}\\times100\n$$  \n\nScanning electron microscopy (SEM, Hitachi SU1510, Japan) was employed to evaluate the bacterial morphology and adhesion. Typically, $500~\\mu\\mathrm{L}$ of bacterial suspension $\\left({3\\times10^{5}\\mathrm{CFU/mL}}\\right)$ was dropped on each sterile coating in a 24-well plate, separately. After culturing for $^{4\\mathrm{h}}$ at $37^{\\circ}\\mathrm{C},$ the coatings were gently rinsed with sterile PBS thrice to take out the loosely attached bacteria. Then, the bacteria that attached on coating surfaces were fixed with $2.5\\%$ glutaraldehyde solution at $4^{\\circ}\\mathrm{C}$ for $^{2\\mathrm{h},}$ followed by rinsing with sterile PBS buffer. Dehydration was performed with a series of ethanol aqueous solutions (25, 50, 75, 95, and $100\\%$ ).  \n\nThe live/dead assay was performed to reveal the bacterial viability and population after contacting with the copolymer coatings. Oneside coated samples in $1\\times1~\\mathrm{cm}^{2}$ area were first individually put into a 24-well plate, then $500\\mu\\mathrm{L}$ of bacterial suspension $\\left(3\\times10^{6}\\mathrm{CFU/mL}\\right)$ and $500\\mu\\mathrm{L}$ of MHB were added into each well. After culturing for $6\\mathrm{{h}}$ at $37\\ ^{\\circ}\\mathrm{C},$ the coatings were rinsed thrice with sterile pure water and stained with $200\\mu\\mathrm{L}$ of propidium iodide (PI)/SYTO 9 mixture for 15 min in the dark. Subsequently, the samples were washed with sterile water again for discarding the residual dye solution, and the stained samples were mounted between a slide and a coverslip and observed under a fluorescence microscope (Nikon Eclipse Ti-S, Japan).  \n\nHemolytic Test. The hemolytic assay was performed as described in refs 16 and 55. In brief, fresh sheep blood was diluted with PBS buffer $\\mathrm{(pH~7.4)}$ and then centrifuged at $2000~\\mathrm{rpm}$ for $10\\ \\mathrm{\\min},$ followed by discarding the supernatants and repeating the above step twice. The washed red blood cell (RBCs) was diluted with PBS in a ratio of 1:9. Then, $500~\\mu\\mathrm{L}$ of $10\\%$ RBC suspension was placed on each prepared $1\\times1~\\mathrm{cm}^{2}$ coating in a 24-well plate, and subsequently $500~\\mu\\mathrm{L}$ of PBS buffer was also added into each well. After incubating at $37^{\\circ}\\mathrm{C}$ for $^{2\\mathrm{h},}$ the whole blood solutions were centrifuged at 2000 rpm for $10\\ \\mathrm{min}$ . Then, aliquots $\\left(100~\\mu\\mathrm{L}\\right)$ of the supernatants were transferred into a 96-well plate, and the OD values at $541~\\mathrm{nm}$ were measured. The untreated blood suspension and blood diluted with water were used as the negative and positive controls, respectively. The hemolysis was calculated by the following eq 4  \n\n$$\n\\mathrm{Hemolysis\\:(\\%)}=\\frac{O D_{\\mathrm{sample}}-O D_{\\mathrm{negative\\:control}}}{O D_{\\mathrm{positive\\:control}}-O D_{\\mathrm{negative\\:control}}}\\times100\\\n$$  \n\n![](images/d98850fab3abe99e8b3bd6b7c05186fa014616328965e0321ad83e30f7846c97.jpg)  \nFigure 3. In vitro antifogging study. (A) Antifogging performances of the prepared coatings with both hot-vapor and cold-warm method. (B) Transmittance of the coatings and bare glass during the cold-warm antifogging test. (C) Evolution of WCA and wetted surface area (S) of the coating samples within $400\\mathrm{~s~}$ . Wetted surface area variation is expressed as $\\Delta S/S_{0},$ where $\\Delta S=S_{(t)}-S_{0},S_{(t)}$ and $S_{0}$ are the wetted surface areas at a given time and initial moment, respectively.",
        "category": " Materials and methods"
    },
    {
        "id": 5,
        "chunk": "# RESULTS AND DISCUSSION  \n\nThe dual-functional antifogging/antibacterial coatings with various POSS-P(QAC-co-AEMA)/P(HEAA- $_c o$ -GMA) ratios were successfully prepared. According to the blending ratios, the resultant coatings were denoted as $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1},$ $\\mathrm{PPQA_{1}/}$ $\\mathrm{PHG}_{1},$ and $\\mathrm{PPQA_{1}/P H G_{2}},$ respectively. As control, two onecomponent coatings were also prepared from POSS-P(QACco-AEMA) and P(HEAA-co-GMA), which were expressed as PPQA and PHG, respectively. Antifogging, bacteria-killing, and bacteria-repelling properties of the blending coatings were systematically evaluated to investigate the relationships between polymer compositions and the coatings’ performance.  \n\nCharacterizations of the Antifogging/Antibacterial Coatings. The structure of the prepared blending coatings was confirmed by ATR−FTIR spectra as shown in Figure 2A. The characteristic peak at $1723~\\mathrm{{\\bar{c}m}^{-1}}$ was attributed to $\\scriptstyle{\\mathrm{C}}={\\mathrm{O}}$ stretching vibration of the ester group, and the absorption peak at $1552~\\mathrm{{cm}^{-1}}$ was corresponding to $\\mathrm{\\DeltaN-H}$ bending vibration of the amide group in HEAA.56 With the adding of P(HEAA-coGMA), the intensity of the peak at $1552~\\mathrm{{cm}^{-1}}$ strengthens gradually, whereas the peak of $1723~\\mathrm{{cm}^{-1}}$ becomes weaker. Moreover, the absorption peak at $3270~\\mathrm{{cm}^{-1}}$ belonged to the $\\mathrm{\\DeltaN-H}$ and $_\\mathrm{O-H}$ stretching vibrations, that were present in all prepared coatings except for the POSS-P(QAC-co-AEMA) coated surface.57 All of the above results indicate that the PPQA/PHG blending coatings have been successfully prepared. One of the basic requirements for antifogging coating is the transparency of the coating itself. Visible light transmittance of the blending coatings as well as bare glass were collected (Figure 2B). The prepared PPQA/PHG blending coatings exhibited highly visible light transmittance of $85.0\\mathrm{-}90.0\\%$ approximately, comparable to that of bare glass $\\left(86.8-91.2\\%\\right)$ , indicating good compatibility of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA). Whereas for the PPQA and PHG coatings, the visible light transmittance values in the wavelength range of $400{-}800~\\mathrm{nm}$ were $79.6\\mathrm{-}84.6$ and $76.9\\mathrm{-}80.8\\%$ , respectively, which are lower than those of bare glass and the prepared PPQA/PHG blending coatings, this was probably due to the higher crosslinking density present in onecomponent PPQA and PHG coatings, decreasing the smoothness of the coating surfaces.  \n\nThe surface morphology of the copolymer coatings was further explored by AFM. It could be obtained from Figure 2C that the root-mean-square roughness $R_{\\mathrm{q}}$ values of PPQA, $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1},$ $\\mathrm{PPQA_{1}/P H G_{1}},$ $\\mathrm{PPQA_{1}/P H G_{2}}$ and PHG coatings were 13.9, 0.7, 0.9, 0.8, and $22.3\\ \\mathrm{nm},$ respectively. The nanoscaled roughness indicated that smooth surfaces were formed, which can facilitate optical transparency.21 Meanwhile, the decreased $R_{\\mathrm{q}}$ values of the PPQA/PHG blending coatings indicate smoother surface topography, suggesting that the two copolymers exhibited good compatibility and no phase separation appeared during the blending process. The higher roughness of the PPQA and PHG coating surfaces could be attributed to strong interactions between the copolymer itself.  \n\nAntifogging Performance. Antifogging performance of the blending coatings was evaluated by both qualitative and quantitative measurements.8−11,16−18 First, optical images were photographed during both hot-vapor and cold-warm antifogging tests as showed in Figure 3A. The bare glass fogged up immediately either placing them over boiling water or after storing in a refrigerator for $30\\mathrm{min}$ , whereas the coated surfaces maintained visible clearness under hot-vapor antifogging measurement, demonstrating a remarkable antifogging behavior. It could be seen that all coatings kept free of fog and the green plants can be seen obviously after storing at $-20\\ ^{\\circ}\\mathrm{C},$ except for the PPQA and PHG coatings, indicating that the foggy environments were harsher with cold-warm method compared with hot-vapor method. The three blending coatings, $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1},$ $\\mathrm{PPQA_{1}/P H G_{1}},$ and $\\mathrm{PPQA_{1}/P H G_{2}},$ qualitatively showed raised transmittance in comparison with the bare glass substrate when exposed to foggy conditions, indicating their excellent antifogging performance. It was mainly attributed to quaternary ammonium, hydroxyl, and amide groups in POSS-P(QAC-co-AEMA) and P(HEAA-coGMA), which can absorb water molecules from the environment and diffuse to prevent a large water domain formation, thus avoiding or reducing light scattering and refraction.  \n\n![](images/a6560ba0c8080bc31038a4af62b62361964d71f3cd1b0780073c17dadd78c1f7.jpg)  \nFigure 4. In vivo antifogging study. (A) Schematic illustration of the in vivo antifogging test using a rabbit oral cavity model, showing photographs of the real digital endoscope and the preparation of the test sample. The circular coating samples ( $\\dot{d}=4.9\\ \\mathrm{mm}$ ) were fitted between the lens and an elastic protective sleeve. (B) Digital photographs of the rabbit’s maxilla taken from the video at different time points.  \n\nSecond, the antifogging properties of the blending coatings were further quantitatively characterized on a visible spectrophotometer, where visible light transmittances of each double-coated surface were collected when exposed to ambient conditions after keeping at $-20~^{\\circ}\\mathrm{C}$ for $30~\\mathrm{min}$ . As shown in Figure 3B, the visible light transmittance of $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1},$ $\\mathrm{PPQA_{1}/P H G_{1}},$ and $\\mathrm{PPQA_{1}/P H G_{2}}$ coatings maintained at $84-$ $90\\%$ and almost the same as those of the coated surfaces before freezing. These results indicated that antifogging properties of the prepared PPQA/PHG blending coatings were almost unaffected by the blending ratios. In contrast, bare glass only has a light transmittance of $28-36\\%$ because of strong light scattering phenomenon. During the cold-warm antifogging test, it could be seen that the light transmittance of PPQA and PHG coatings were $^{67-78}$ and $52\\mathrm{-}67\\%$ , respectively, which was consistent with the above results of optical images. The discounted antifogging behavior was probably due to their higher crosslinking density in comparison with the other three coatings that blended POSS-P(QAC-co-AEMA) with P(HEAA-co-GMA). Furthermore, the antifogging performance of $\\mathrm{PPQA_{1}/P H G_{1}}$ and POSS-free $\\mathrm{PQA_{1}/P H G_{1}}$ coatings was compared, and the result suggested that POSS had little effect on antifogging ability of the blending coatings prepared in this work (Figure S3), but it was demonstrated that the introduction of POSS was beneficial to the coating stability (Figure S4).  \n\nIt is widely accepted that surface wettability plays a significant role in antifogging performance. To investigate the origin and difference in antifogging capability of the prepared copolymer coatings, time-dependent WCA measurements over a 400 s period were performed and the results are shown in Figure 3C. Evidently, all coating surfaces had an initial WCA value about $110^{\\circ}$ and then gradually dropped until stable, which was in contrast to that of bare glass (tiny change with time due to water evaporation). It was considered that the prepared coatings belonged to the typical water-absorbed coatings that show the WCA in the range of 40−110°.14 Reasonably, the antifogging properties of the prepared coatings were attributed to the strong water absorption capability, and subsequently spread it into a hydrated film via hydrogen bonds. Compared with the one-component coatings of PPQA and PHG, the blending $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1},$ $\\mathrm{PPQA_{1}/P H G_{1}},$ and $\\mathrm{PPQA_{1}/P H G_{2}}$ coatings displayed a relative rapid decrease of WCA to $57.7\\pm0.9$ , $53.8\\pm0.4_{;}$ , and $63.6\\pm1.4^{\\circ}$ within $400\\ \\mathrm{s},$ respectively, more quickly than both PPQA and PHG coatings (stable WCA values were $82.2~\\pm~3.1$ and $74.5~\\pm~4.0^{\\mathrm{\\bar{o}}}.$ , respectively), resulting in an enhancement of the antifogging performance. It was assumed that the rapid decrease of WCA was probably due to the formation of moderate crosslinking density in the PPQA/PHG blending coatings, which was more conducive to the water absorption process. Further comparison of the wettability of the PPQA/PHG coating exhibited that the $\\mathrm{PPQA_{1}/P H G_{1}}$ coating surface was the most hydrophilic. As mentioned above, PHG coating was highly crosslinked owing to many more crosslinking sites of hydroxyl groups, thus its water-absorbing capability was restricted to some extent, resulting in unsatisfactory antifogging performance. On the other hand, the coating would become more hydrophobic with increased content of POSS-containing copolymer POSSP(QAC-co-AEMA). In consequence, no matter whose content is higher, it is not helpful to absorb water molecules for coated surfaces. In order to study the wetting properties more indepth, Figure 3C showed the wetted surface area evolution $(\\bar{\\Delta S}/S_{0})$ over $400\\mathrm{~s~}$ time interval for the coated samples as well as bare glass. The wetted surface area of bare glass remained nearly unvaried with time, whereas all coated surfaces had an increased trend in wetted surface area, indicating that the water droplets had spread. For PPQA/PHG blending coatings, the values of $\\Delta S/S_{0}$ kept going up to nearly $100\\%$ within $400\\ \\mathrm{s}.$ . However, after an increase of $50\\%$ over the first $^{60\\mathrm{~s,~}}$ the wetted surface areas of PPQA and PHG coatings remained unchanged. These results also demonstrated that the blending coatings had stronger water-absorbing capability than that of one-component coatings.  \n\n![](images/c42f9166e9ad83b38c463218247b6025ee0df8c822076ecf7d213538e5d1a0c4.jpg)  \nFigure 5. Antibacterial properties. (A) Growth inhibition rates of POSS-P(QAC-co-AEMA) copolymers in aqueous solutions with a sequence of concentrations against S. aureus and $E$ . coli. (B) Photographs of bacterial colonies of S. aureus and $E_{\\sun}$ coli after incubation with various coatings and bare glass at $37~^{\\circ}\\mathrm{C}$ for $24\\mathrm{~h~}$ . (C) Growth inhibition rates of the prepared coatings calculated by standard plate count methods. All data were obtained from at least three samples.  \n\nAntifogging is considered as the principal intention when emphasized for use in vivo. Therefore, the superior in vivo antifogging effects of the blending coatings were further demonstrated by using a rabbit oral cavity model as shown in Figure 4A. The endoscope images of the whole operating process were recorded. For each, the digital photographs at predetermined moments $(\\sim2,\\sim30,$ and ${\\sim}60~\\mathrm{s}$ ) were captured from the corresponding video and are presented in Figure 4B. Fog formed immediately on the bare glass surface after it was put into the humid oral environment, and visible optical loss occurred after insertion for about $30\\mathrm{~s~}$ due to strong light scattering (Figure 4B and Video S1). It is noteworthy that some visual acuity still remained at $^{2\\ s,}$ indicating that the blurry vision was caused by the endoscope lens fogging, rather than being out of focus. Fortunately, all coated samples remained optically clear and the rabbit’s maxillae were highly visible at $^{30\\mathrm{~s,~}}$ demonstrating the antifogging performance. Furthermore, it could be seen that after $^{60}\\ s,$ the onecomponent coatings, especially for PHG coating, had a compromised antifogging property in comparison with the other three PPQA/PHG coatings. It was consistent with the results of the antifogging tests in vitro, but the blending coatings such as $\\mathrm{PPQA_{1}/P H G_{2}}$ still kept visually clear even under strong fogging conditions for $120\\ s$ (Video S2), showing high efficiency in preventing fog formation.  \n\nAntibacterial Properties. The antibacterial activity was first evaluated by testing MIC of copolymers against both Gram-positive bacteria, Staphylococcus aureus and Gramnegative bacteria, Escherichia coli. As shown in Figure 5A, the cationic copolymer of POSS-P(QAC-co-AEMA) had MIC values of 128 and $256~\\mu\\mathrm{g/mL}$ toward S. aureus and E. coli, respectively, which displayed reasonable antibacterial activity in comparison with antimicrobial polypeptides, antibiotic, or sliver-based antibacterial systems that exhibited MIC lower than $100~\\mu\\mathrm{g/mL}$ or even less than $10~\\mu\\mathrm{g/mL}.^{58-61}$ On the other hand, P(HEAA-co-GMA) has no antibacterial activity due to the lack of antimicrobial groups.  \n\nThe antibacterial properties of the copolymer coatings were investigated via the standard plate count method. As illustrated in Figure 5B, there were lots of bacteria colonies covered on a plate of the control sample. In sharp contrast, almost no colonies could be observed on cationic PPQA coating plates, both toward S. aureus and E. coli, suggesting that cationic QAC has excellent bactericidal activity. The blending coatings with different PPQA/PHG ratios of $2/1,1/1$ , and $1/2$ were also detected in this measurement. It could be seen from Figure 5B that there were also no bacteria colonies on the $\\mathrm{PPQA_{2}/P H G_{1}}$ plate and with the increased ratio of POSS-P(QAC-co-AEMA), the number of bacterial colonies declined, whereas PHG coating exhibited a similar result as that of bare glass. It could be concluded from the above results that hydroxyl-containing copolymer P(HEAA-co-GMA) had almost no contribution to bactericidal performance, but appropriate incorporation into coatings could still maintain the antibacterial performance compared with the PPQA sample.  \n\nThe antibacterial activities of the prepared coatings were further quantitatively investigated to obtain the growth inhibition rates by counting the number of bacteria colonies as shown in Figure 5B. It can be seen in Figure 5C that the growth inhibition rates of PPQA and $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1}$ coatings nearly hit $99.9\\%$ against S. aureus and E. coli. With the increase of P(HEAA-co-GMA) content, $\\mathrm{PPQA_{1}/P H G_{1}},$ $\\mathrm{PPQA_{1}/P H G}_{2},$ and PHG coatings showed reduced bacterial growth inhibition rates at $67.2\\pm{\\:3.9}_{}$ , $47.7\\pm9.2\\$ , and $1.7\\pm5.3\\%$ , respectively, against E. coli. It could be assumed that the PPQA/PHG ratio had a significant effect on the antibacterial properties of the blending coatings. Meanwhile, it could be observed that the growth inhibition rate of $\\mathrm{PPQA_{1}/P H G_{1}}$ also reached $99.9\\%$ against S. aureus, indicating that the antibacterial activity of the prepared blending coatings against S. aureus was stronger than that of $E_{\\rightleftarrows}$ . coli, which was in accordance with the MIC results. This could be possibly related to the bacterial cell structure.62,63 Compared with Gram-positive S. aureus, an additional lipopolysaccharide-containing membrane was present in the structure of the Gram-negative $E$ . coli, thus making membrane destruction more difficult. Moreover, the antibacterial activities of POSS-free copolymer of P(QAC-coAEMA) and $\\mathrm{PQA_{1}/P H G_{1}}$ blending coating were also tested (Figure S5). The results indicated that POSS had little effect on antibacterial properties in this study. In addition, as suggested for potential applications for endoscopes, the blending coatings were also demonstrated to have long-term and recycling antibacterial property (Figure S6).  \n\nThe bacteria-associated infection begins with the adhesion of bacteria to the device surfaces. Therefore, endowing surfaces with bacteria-repellency is critical for biomaterial applications. Both S. aureus and E. coli were used to assess bacterial attachment on the coating surfaces. The bacterial attachment on the coating and bare glass, as well as bacterial morphology after incubation with the prepared coatings for $6\\mathrm{~h~}$ were observed by SEM (Figure 6). It could be seen that a large number of bacteria adhered on the PPQA coating and bare glass surface. Bacterial attachment on the blending coating surfaces decreased gradually with the increased amount of P(HEAA-co-GMA). Few bacteria were observed on the PHG coating surface, suggesting superior bacteria-repellent ability. Hydrogen-bonding interactions with hydroxyl and amide groups make the PHG coating surface form a hydrated layer to resist bacterial adhesion. On the other hand, drastic morphologic evolvements were witnessed either in S. aureus or E. coli, in which the bacteria membranes became wrinkled after incubation with PPQA coating, whereas the control of both S. aureus and E. coli on bare glass displayed a structurally intact cell wall. This could be attributed to the strong antibacterial activity of cationic QAC groups which could disrupt the membrane of bacteria by initial contact through an electrostatic effect and passive diffusion of the polymer chains (the alkyl chains) through the cell wall.  \n\nFurthermore, bacterial viability was detected on a fluorescence microscope after staining. Green fluorescent dye (STYO 9) generally labels all bacteria, whereas red fluorescent dye (PI) penetrates only bacteria with damaged membranes. As shown in Figure 7, numerous dead cells were seen both on the PPQA and $\\mathrm{PPQA}_{2}/\\mathrm{PHG}_{1}$ surfaces after incubation for $6\\mathrm{{h}}$ This phenomenon confirms again that the cationic POSSP(QAC-co-AEMA) copolymer plays a vital role for antibacterial activities. Because of the hydrophilicity of P(HEAA$c o$ -GMA), the amount of bacteria attached on $\\mathrm{PPQA_{1}/P H G_{2}}$ and PHG surfaces significantly decreased, demonstrating their excellent bacteria-repellent property. The tendency agreed well with that observed in SEM images. $\\mathrm{PPQA_{1}/P H G_{1}}$ coating showed an effective bacteria-repelling performance, and maintained bacterial growth inhibition rates of 99.9 and $67.2\\%$ against S. aureus and E. coli, respectively, being considered as the optimum in this work. It could be concluded from the above antibacterial and bacterial adhesion results that it was meaningful to balance the ratio of bactericidal POSSP(QAC-co-AEMA) and anti-adhesive P(HEAA-co-GMA) for achieving the best comprehensive antibacterial performance.  \n\n![](images/ef3d257d13c511d0c32a4076d19a6559efd56986aa2f3fb6b19507c4fefe5cec.jpg)  \nFigure 6. SEM images of S. aureus (A) and E. coli (B) adhering to the prepared coatings after incubation for $^{6\\mathrm{~h~}}$ .  \n\n![](images/efd9a639ce8194823cb4811563f109fc028e46d5bafb612c305f1c5688f69c1e.jpg)  \nFigure 7. Fluorescent images of S. aureus (A) and $E$ . coli (B) on the prepared coating surfaces after incubation for $\\epsilon\\mathrm{h}$ . Red indicates dead bacteria, and green refers to live bacteria.  \n\nHemolytic Analysis. One of the challenges of cationic antibacterial materials is hemolytic activity. In this work, hemolytic rates of the resultant coatings were measured, and the results are shown in Figure 8. Pure water and PBS buffer were chosen as the positive and negative controls, respectively. After incubating with RBCs for $^{2\\mathrm{h}}$ , cationic PPQA coating had a hemolytic rate of $13.25\\pm0.40\\%$ , whereas for PHG coating, almost no hemolysis was observed $\\left(-0.06~\\pm~0.50\\%\\right)$ , suggesting compatibility with RBCs. It could be seen that the hemolysis rates of $\\mathrm{PPQA_{2}/P H G_{1}},$ $\\mathrm{PPQA_{1}/P H G_{1}},$ and $\\mathrm{PPQA_{1}/P H G_{2}}$ were $0.33\\pm\\:0.28$ , $0.86\\pm\\:0.03$ , and $3.89\\pm$ $0.01\\%$ , respectively, and all of them were less than $5\\%$ , meeting the clinical application requirement.64 After blending with P(HEAA-co-GMA), the hemolysis of the coatings reduced obviously as compared with that in the PPQA coating, which was because hydroxyl groups could interact with RBC surfaces by weak hydrogen-bonding, and thus protect RBCs from being destroyed,65 which was consistent with the previous work.66,67 The cytotoxicity of the coatings was also tested (Figure S7), though the cytotoxicity was not low.  \n\n![](images/2c8f292bd213b48d5cc3f9412250adb38d7d82d541d1f262a654154976cc8dcc.jpg)  \nFigure 8. Hemolysis of the prepared blending coatings showing low values in comparison to the homopolymer PPQA coatings. All data were obtained from at least three samples and shown as the mean $\\pm$ standard deviation.  \n\nThe prepared PPQA/PHG blending coatings had antifogging and antibacterial properties simultaneously. As illustrated in Figure 9, both the cationic polyelectrolyte of QAC and two hydrogen-bond donor-containing HEAA in copolymers are responsible for rapidly absorbing water molecules from the environment and diffusing them into the bulk of the coatings via hydrogen-bonding interactions, that can greatly reduce light reflection or refraction and endow the surfaces with antifogging performance. The antibacterial properties of the blending coatings are triggered by the bacteria-killing and bacteriarepelling balance that was provided by positively charged POSS-P(QAC-co-AEMA) and hydrophilic P(HEAA-co-GMA), respectively. The coexistence of hydroxyl and amide groups rendered HEAA as a strong hydratable, which prevented the initial attachment of bacteria onto the device surfaces. Meanwhile, QAC was employed to kill the residual adhered bacteria through immobilizing the negative bacterial cell envelopes via electrostatic interaction and disrupting the membrane structure by alkyl chains. The dual functionality of the blending coatings suggests the excellent potential of this type of functionalization for medical devices.  \n\n![](images/8f72cf162eba325932e4f0d511ca6f032e0cda9f1c7dd28003a76cb362d317b7.jpg)  \nFigure 9. Illustration of antifogging and antibacterial performances of the PPQA/PHG blending coatings. Both cationic and hydroxylcontaining copolymers are responsible for the antifogging performance due to water absorption and diffusion, and they also provide bacteria-killing and bacteria-repelling properties.",
        "category": " Results and discussion"
    },
    {
        "id": 6,
        "chunk": "# CONCLUSIONS  \n\nIn this work, transparent, antifogging and antibacterial blending coatings were successfully prepared by casting the mixed copolymer solution of POSS-P(QAC-co-AEMA) and P(HEAA-co-GMA) in a simple and green approach. The two random copolymers are compatible as demonstrated by high transparency comparable to that of bare glass and nanoscaled roughness of the coating surfaces. Based on the hydrophilic HEAA and QAC, the resultant coatings with various blending ratios could effectively prevent fog formation under hot-vapor and cold-warm conditions. Meanwhile, in vivo antifogging study suggested that the PPQA/PHG blending coatings can remain optically clear under humid oral environments. Furthermore, it was found that the PPQA coating showed remarkable antibacterial property and the increased ratio of POSS-P(QAC-co-AEMA) in blending coatings could improve the bactericidal effect. On the other hand, neat PHG coating showed strong resistance to bacterial attachment. By tuning the bacteria-killing and bacteria-releasing properties among the copolymers of POSS-P(QAC-co-AEMA) and P(HEAA-coGMA), the blending coating with $1/1$ mass ratio simultaneously showed effective bacteria-repelling performance and maintained bacterial growth inhibition rates of 99.9 and $67.2\\%$ against S. aureus and E. coli, respectively, as well as the low hemolytic rate of $0.86\\pm0.03\\%$ . This work provides a facile approach to develop an antifogging/antibacterial polymeric coating, which could be potentially applied in medical devices of endoscopy or other related fields such as food preservation.",
        "category": " Conclusions"
    },
    {
        "id": 7,
        "chunk": "# ASSOCIATED CONTENT",
        "category": " References"
    },
    {
        "id": 8,
        "chunk": "# $\\bullet$ Supporting Information  \n\nThe Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsami.9b21871.  \n\nMaterials, synthesis procedures of QAC, POSS-CPADB, POSS-P(QAC-co-AEMA), and P(HEAA-co-GMA), as well as their characterizations by $^{1}\\mathrm{H}$ NMR and GPC; thickness, stability, recycling antibacterial properties, and cytotoxicity of the coatings, and antifogging and antibacterial properties of $\\mathrm{PQA_{1}/P H G_{1}}$ coating (PDF)  \n\nIn vivo antifogging performance of bare glass (AVI) In vivo antifogging performance of the $\\mathrm{PPQA_{1}/P H G_{2}}$ coating (AVI)",
        "category": " Materials and methods"
    },
    {
        "id": 9,
        "chunk": "# AUTHOR INFORMATION",
        "category": " References"
    },
    {
        "id": 10,
        "chunk": "# Corresponding Authors  \n\nXiaohui Li − School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300350, China; $\\circledcirc$ orcid.org/ 0000-0003-3179-6585; Email: lixiaohui@tju.edu.cn Xiaoyan Yuan − School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300350, China; orcid.org/0000-0002-2895-3730; Email: yuanxy@ tju.edu.cn",
        "category": " Abstract"
    },
    {
        "id": 11,
        "chunk": "# Authors  \n\nShan Bai − School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300350, China Yunhui Zhao − School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300350, China Lixia Ren − School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300350, China; orcid.org/0000-0001-7659-0025  \n\nComplete contact information is available at: https://pubs.acs.org/10.1021/acsami.9b21871",
        "category": " References"
    },
    {
        "id": 12,
        "chunk": "# Notes  \n\nThe authors declare no competing financial interest.",
        "category": " References"
    },
    {
        "id": 13,
        "chunk": "# ACKNOWLEDGMENTS  \n\nThis work is financially supported by the National Natural Science Foundation of China under grant 51603143 (X.L.) and the Natural Science Foundation of Tianjin, China via grant 18JCQNJC03800 (X.L.) and 17JCZDJC37500 (X.Y.). Prof. Junmei Zhu at Tianjin Institute of Medical and Pharmaceutical Science, China, is appreciated for providing support of the in vivo antifogging test.",
        "category": " References"
    },
    {
        "id": 14,
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        "category": " References"
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]