Fabrication of carbohydrate microarrays on a poly(2-hydroxyethyl methacrylate)-based photoactive substrate

Abstract

We report the fabrication of carbohydrate microarrays on a photoactive polymer, poly(HEMA-co-HEMA-PFPA), synthesized by RAFT copolymerization of 2-hydroxyethyl methacrylate (HEMA) and perfluorophenyl azide (PFPA)-derivatized HEMA (HEMA-PFPA). PFPA allows the covalent immobilization of carbohydrates whereas the HEMA polymer provides an antifouling surface, thus the microarrays can be used directly without pretreating the array with a blocking agent. The microarrays were prepared by spin-coating the polymer followed by printing the carbohydrates. Subsequent irradiation simultaneously immobilized the carbohydrates and crosslinked the polymer matrix. The obtained 3D carbohydrate microarrays showed enhanced fluorescence signals upon treating with a fluorescent lectin in comparison with a 2D microarray. The signals were acquired at a lower lectin concentration and a shorter incubation time. When treated with E. coli bacteria, the carbohydrate microarray showed results that were consistent with their binding patterns.

Synthesis of Polyphosphazenes by a Fast Perfluoroaryl Azide-Mediated Staudinger Reaction

“…Compound 1b was synthesized according to the reported protocol . In brief, a solution of 4-azido-2,3,5,6-tetrafluoro­benzoic acid (1.00 g, 4.30 mmol) in dry dichloromethane (20 mL) was stirred with ethylene glycol (132 mg, 2.10 mmol) and DMAP (53 mg, 0.43 mmol) under Ar at room temperature for 30 min.…”

“…Perfluoroaryl azides (PFAAs), originally developed as highly efficient photoaffinity labels owing to the increased lifetime of the singlet perfluoroaryl nitrene generated by photoactivation of the azide, have been applied for the functionalization of materials and surfaces , and for the conjugation of a wide range of structures including drug molecules, polymers, , carbohydrates, − and nanoparticles. − Additionally, the azide in PFAA is a highly electrophilic dipole activated by the multiple fluorine atoms. For instance, the LUMO of pentaphenyl azide is 3.06 eV compared to 3.68 eV in the case of phenyl azide. , This electrophilic activation results in orders of magnitude increase in the reaction rates and enables new reactions of PFAAs that are unique and impossible with phenyl azide, for example, azide–thioacid amidation, azide–aldehyde amidation, , azide–alkyne cycloaddition, ,− and Staudinger reaction .…”

Carbohydrate microarrays fabricated on poly(2-methylacrylic acid)-based substrates for analysis of carbohydrate–protein interactions

“…In order to improve the performance of carbohydrate microarray-based assays, more recent studies have focused on improving the detection sensitivity by increasing specific binding and decreasing background noise. 9 On one hand, increasing the carbohydrate loading capability 10 and varying the carbohydrate presentation on the substrates, such as the spacing and orientation of the carbohydrate ligands to guarantee multivalent binding, can significantly enhance specific binding. Liu et al adopted silica nanoparticle-coated glass substrates with post-modification with a poly(glycidylmethacrylate) brush layer for carbohydrate microarray fabrication so as to improve the carbohydrate loading capacity on the substrates, and the obtained carbohydrate microarrays exhibited good sensitivity and strong multivalent interactions.…”

“…13 It can be realized by shielding the substrates of microarrays with a polymer brush with anti-nonspecific adsorption properties, such as poly(2-hydroxyethyl methacrylate) (pHEMA). 9,14 In our previous study, we established a sensitive pHEMA-CC-based carbohydrate microarray fabrication method by site-nonspecifically immobilizing carbohydrates on substrates. 15 In this study, a poly(2-methylacrylic acid) (pMAA)-modified substrate was adopted for microarray fabrication to sitespecifically immobilize carbohydrates on substrates in order to satisfy diversified demands for carbohydrate microarraybased assays.…”

A Novel Optical Method To Reversibly Control Enzymatic Activity Based On Photoacids

“…The latter requires a receptor or transducer that responds to the radiation in a defined manner. This receptor can either be the enzyme in the biochemical reaction itself 1–3 , the substrate 4,5 or inhibitor 6–8 . Especially engineering of proteins to become photoresponsive is very difficult to achieve and not applicable to all enzymes, therefor optical control of substrate or inhibitor may represent a more simple alternative.…”