Molecularly Imprinted Cryogels for the Selective Adsorption of Salicylic Acid

In this study, molecularly imprinted cryogels were fabricated for selective adsorption of salicylic acid. Cryogelation was performed at - 20 °C using a cationic monomer N,N-dimethylaminoethyl methacrylate as a functional monomer for salicylic acid. The morphology, swelling behaviors, and chemical structures of the cryogels were investigated. The general structure and porosities of cryogels were compared with the traditional hydrogels using field emission scanning electron microscopy (FE-SEM). The adsorption performance of cryogels toward salicylic acid was studied to investigate the optimal adsorption conditions. Adsorption capacity of the imprinted cryogels was 1.95 and 7.51 times higher than those of non-imprinted and bare PHEMA cryogels, respectively, due to the specific binding sites toward salicylic acid. Molecularly imprinted cryogels exhibited significant stability and reusability by keeping more than 85% of their adsorption capacity after ten regeneration cycles. Considering the fabrication process, adsorption capacity, selectivity, and reusability of the imprinted cryogels, these new materials could be utilized as a promising alternative for selective adsorption of drug molecules.

A general photoiniferter approach to the surface functionalization of acrylic and methacrylic structures written by two-photon stereolithography

Two-photon stereolithography (TPS) is an established additive fabrication technique allowing the voxel-by-voxel direct writing of even intricate 3D nano/microstructures via the polymerization of a photoresin. An obvious way to tune the chemical functionalities of such nano/microstructures is formulating a photoresin with the desired functional monomer(s). Unfortunately, this makes every photoresin "unique" in terms of viscosity and reactivity, thus requiring a tedious and often time-consuming optimization of its printing parameters. In this work, we describe a general approach for the chemical functionalization of TPS-written structures based on two commercial photoresins. Our strategy entailed the grafting of functional polymer layers via an innovative approach based on photoiniferter coupling to unreacted double bonds and photopolymerization. After writing woodpiles as 3D model structures, we demonstrated the viability of this approach by anchoring a photoiniferter via its photoinduced addition to the residual CC on the structure's surface triggered by green light. This in turn allowed for the blue light-mediated, surface-initiated photopolymerization of functional monomers. Molecularly imprinted polymer films were also easily synthesized by using the same approach on model honeycombs. The imprinted layers resulted in only a minimal increase in size with no effect on the geometrical features of the honeycombs. Overall, this strategy offers a general approach for the surface modification of TPS-written (meth)acrylic structures with a wide variety of functional polymers via photoiniferter polymerization.

Construction of PEGylated boronate-affinity-oriented imprinting magnetic nanoparticles for ultrasensitive detection of ellagic acid from beverages

Molecularly imprinted polymers (MIPs) can exhibit antibody-level affinity for target molecules. However, the nonspecific adsorption of non-imprinted regions for non-target molecules limits the application range of MIPs. Herein, we fabricated PEGylated boronate-affinity-oriented ellagic acid-imprinting magnetic nanoparticles (PBEMN), which first integrated boronate-affinity-oriented surface imprinting and sequential PEGylation for small molecule-imprinted MIPs. The resultant PBEMN possess higher adsorption capacity and faster adsorption rate for template ellagic acid (EA) molecules than the non-PEGylated control. To prove the excellent performance, the PBEMN were linked with hydrophilic boronic acid-modified/fluorescein isothiocyanate-loaded graphene oxide (BFGO), because BFGO could selectively label cis-diol-containing substances by boronate-affinity and output ultrasensitive fluorescent signals. Based on a dual boronate-affinity synergy, the PBEMN first selectively captured EA molecules by boronate-affinity-oriented molecular imprinted recognition, and then the EA molecules were further labeled with BFGO through boronate-affinity. The PBEMN linked BFGO (PBPF) strategy provided ultrahigh sensitivity for EA molecules with a limit of detection of 39.1 fg mL^-1, resulting from the low nonspecific adsorption of PBEMN and the ultrasensitive fluorescence signal of BFGO. Lastly, the PBPF strategy was successfully employed in the determination of EA concentration in a spiked beverage sample with recovery and relative standard deviation in the range of 96.5 to 104.2% and 3.8 to 5.1%, respectively. This work demonstrates that the integration of boronate-affinity-oriented surface imprinting and sequential PEGylation may be a universal tool for improving the performance of MIPs.

One-step synthesis of well-defined molecularly imprinted nanospheres for the class-selective recognition and separation of β-blockers in human serum

β-blockers are a class of medications that are used to treat abnormal heart rhythms and hypertension. Molecularly imprinted polymers (MIPs) capable of selective recognizing and extracting β-blockers from complex biological samples hold great promise in bioanalytical and biomedical applications, but developing such artificial receptor materials is still challenging. Herein, we introduce a simple one-step method for the synthesis of well-defined molecularly imprinted nanospheres in high yield (83.6-94.4%) via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization for the selective recognition and extraction of the β-blockers from human serum. The prepared MIPs are characterized in terms of morphology, pore properties, binding kinetics, capacity, selectivity, and recognition mechanisms. The uniform nanoscale-imprinted layer favored the rapid mass transfer of β-blockers. The binding studies showed the high adsorption capacity (126.8 μmol/g) and selectivity of the developed nanomaterial. The investigation on the recognition mechanism reveals that multiple driving forces participate in the binding between MIP and β-blockers, where hydrogen bonding plays as the dominating role for the specific recognition. The MIP was successfully applied for the direct enrichment of five β-blockers from human serum with HPLC recoveries ranging from 82.9 to 100.3% and RSD of 0.5-6.9% (n = 3).

Customizable molecular recognition: advancements in design, synthesis, and application of molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) are unlocking the door to synthetic materials that are capable of molecular recognition.