Preparation of Boronic Acid-Functionalized Cryogels Using Modular and Clickable Building Blocks for Bacterial Separation

Abstract

Composite cryogels containing boronic acid ligands are synthesized for effective separation and isolation of bacteria. The large and interconnected pores in cryogels enable fast binding and release of microbial cells. To control bacterial binding, an alkyne-tagged boronic acid ligand is conjugated to azide-functionalized cryogel via the Cu(I)-catalyzed azide–alkyne cycloaddition reaction. The boronic acid-functionalized cryogel binds Gram-positive and Gram-negative bacteria through reversible boronate ester bonds, which can be controlled by pH and simple monosaccharides. To increase the capacity of affinity separation, a new approach is used to couple the alkyne-tagged phenylboronic acid to cryogel via an intermediate polymer layer that provides multiple immobilization sites. The morphology and chemical composition of the composite cryogel are characterized systematically. The capability of the composite cryogel for the separation of Gram-positive and Gram-negative bacteria is investigated. The binding capacities of the composite cryogel for Escherichia coli and Staphylococcus epidermidis are 2.15 × 10 9 and 3.36 × 10 9 cfu/g, respectively. The bacterial binding of the composite cryogel can be controlled by adjusting pH. The results suggest that the composite cryogel may be used as affinity medium for rapid separation and isolation of bacteria from complex samples.

Affinity monolith chromatography: A review of general principles and recent developments

“…This approach is relatively simple and is compatible with a wide range of functional groups [123]. This method has been used to place boronate affinity ligands within monoliths [123,197]. This approach starts with activating the monolith with sodium azide (NaN 3 ).…”

“…In AMC, a triazine‐based biomimetic ligand was used with a chitosan and PVA monolith to purify IgG [298]. Boronates have been used in AMC for the separation of glycoproteins, saccharides, nucleosides, and other cis ‐diol compounds [197,297,299–302]. Types of monoliths that have been used with boronate affinity ligands have included cryogels, MIPs, inorganic monoliths, organic monoliths, and hybrid monoliths [123,197,297,300,301].…”

“…Boronates have been used in AMC for the separation of glycoproteins, saccharides, nucleosides, and other cis ‐diol compounds [197,297,299–302]. Types of monoliths that have been used with boronate affinity ligands have included cryogels, MIPs, inorganic monoliths, organic monoliths, and hybrid monoliths [123,197,297,300,301]. An example is a restricted access boronate monolith that was developed to bind IgG in the carbohydrate groups of its F c region [297].…”

Rapid and Sensitive Fluorescence Detection of Staphylococcus aureus Based on Polyethyleneimine-Enhanced Boronate Affinity Isolation

“…Considering the rich content of cis-dihydroxyl compounds on the surface of bacteria walls, such as lipopolysaccharide, peptidoglycan, and glycoprotein, recently boronate affinity has been reported as a new and effective tool for selective separation of bacteria in surface-enhanced Raman scattering and electrochemical analysis [ 14 , 15 ]. Various carriers such as agarose, cryogels, and magnetic nanobeads have been used to prepare boronate affinity materials [ 16 , 17 , 18 ] and demonstrated the potential to fulfill certain requirements. Until now, the effective combination of boronate affinity with fluorescent assays for food pathogens was still very limited.…”

Freezing-triggered gelation of quaternized chitosan reinforced with microfibrillated cellulose for highly efficient removal of bilirubin

“…Additionally, various polysaccharide-based cryogels by chemical crosslinking have also been explored. [40][41][42][43][44] However, during the freezing process, chemical crosslinking and ice crystal growth occur simultaneously, which leads to relatively loose pore walls and consequently weak mechanical strength. 45 Only the formation of ice crystals prior to gelation enables the chemical crosslinking of the polysaccharides in the concentrated phase, resulting in dense pore walls associated with strong mechanical properties.…”