{
    "protocol": "To synthesize hydrophilic polymers with functional groups, start with crosslinking poly(allylamine hydrochloride) (PAH) and template the polymer with d-glucose 6-phosphate monobarium salt (GPS-Ba). The hydrogel should then be covalently bonded to gold-coated glass slides to create the chemical recognition sites. This will involve utilizing the hydrogen bonding and π-π stacking interactions between the template and monomers in solution. Ensure to facilitate self-assembly of the positively charged polymer around the negatively charged phosphate group of the template. After the template is removed, the hydrogel will allow for the detection of glucose based on refractive index changes due to physical swelling upon analyte binding.To prepare the MIH, a 20 mL aqueous solution containing 0.1 mg/mL poly(allylamine hydrochloride) (PAH), 0.5 mg/mL d-glucose phosphate barium salt (GPS-Ba), and sufficient 1 M NaOH to raise the solution pH to 9 was stirred for 30 min prior to adding DSP-modified gold-coated slides. After 3 h, 5 mL of 0.03 M epichlorohydrin was added to crosslink the hydrogel and the solution was stirred overnight. The slides were then rinsed with deionized water and dipped in 4 M NaOH solution overnight to extract the template, followed by dipping in stirred deionized water for 30 min to thoroughly rinse off the NaOH. For slides with NHS-MHA, 1 mg/mL GPS-Ba was added to the polymer solution and 0.2 M NaOH was used to remove the template after imprinting. Finally, the slides were dried under a stream of dry nitrogen and stored under atmospheric conditions until used.Gold nanoparticles were synthesized by a modified Turkevitch method. The pH of a 10 mL 0.001 M HAuCl4 3H2O solution was adjusted to 7.2 with 1 M NaOH. The solution was heated to boiling and 5% (w/w) sodium citrate was added to achieve a 2:1 ratio between citrate and HAuCl4. The boiling solution was continuously stirred for 1 hour until it turned a wine-red color. The colloid solution was allowed to cool to room temperature, and then several drops of a 1 M cysteamine hydrochloride in 1 M NaOH solution were added until the colloid turned blue, indicating modification with the cysteamine capping agent. A 5 mL aliquot of this solution was added to the PAH solution immediately prior to the addition of epichlorohydrin. The volume of the 0.03 M epichlorohydrin was adjusted to 6.25 mL to maintain the concentration of the cross-linker.Each sensing cycle began with equilibration of the coating in water, followed by exposure to the analyte and then a water washing step to remove non-specifically bound species. At the end of each cycle, 0.1 M NaOH was flushed to regenerate the sensor surface. Each step lasted for 10 min."
}