Green synthesis of hydrophilic protein-imprinted resin with specific recognition of bovine serum albumin in aqueous matrix.

The synthesis of biomacromolecule imprinted materials is a challenge with the bulkiness and instability of macromolecule, such as protein. A green strategy to prepare hydrophilic protein-imprinted resin (HPIR) was firstly developed using resorcinol and melamine as double functional monomers, hexamethylenetetramine instead of formaldehyde as crosslinker, water as solvent, and bovine serum albumin (BSA) as a dual-function template. BSA as dual-function template could not only act as template but also porogen in the preparation of HPIR. According to the adsorption experiments, the adsorption kinetics of BSA on HPIR obeyed pseudo-second-order adsorption kinetics and the equilibrium data were best described by Langmuir isotherm model. The adsorption capability was 44.3459 mg g-1 (25 °C), and the imprinted factor for binding BSA is 5.78. HPIR showed high adsorption capacity, fast mass transfer rate, and specific selectivity towards BSA in aqueous solvent. More importantly, HPIR can be applied to selectively adsorb target protein BSA in urine without the matrix interference of biological matrix, therefore, it is promising for HPIR to be applied to proteomics, diagnostics, and pharmaceutics.

Hydrophilic Molecularly Imprinted Resorcinol-Formaldehyde-Melamine Resin Prepared in Water with Excellent Molecular Recognition in Aqueous Matrices.

Hydrophilic molecularly imprinted resorcinol-formaldehyde-melamine resin (MIRFM) is synthesized in water and shows excellent molecular recognition in aqueous matrices. The double functional monomers resorcinol and melamine, and the cross-linker formaldehyde, are all hydrophilic, and then the hydrophilic groups (such as hydroxyls, imino groups, and ether linkages) can be introduced into MIRFM, which make the material compatible with aqueous samples. The general principle is demonstrated by the synthesis of MIRFM using sulfanilamide as a dummy template for the selective recognition to sulfonamides (SAs) in milk samples. Resorcinol and melamine can interact with the template mainly by hydrogen bonding and π-π interaction, which makes MIRFM and the analytes have strong affinity. Besides, melamine can improve the rigidity of MIRFM and accelerate the polymerization process, so there is no need to add base or acid as a catalyst, which guarantees the success of molecular imprinting. MIRFM shows higher recovery and improved purification effect for SAs, in comparison to silica, HLB, C18, and SCX. Because of its excellent hydrophilicity and specificity, MIRFM is promising to be applied in biological, environmental, and clinical fields.

Glyoxal-Urea-Formaldehyde Molecularly Imprinted Resin as Pipette Tip Solid-Phase Extraction Adsorbent for Selective Screening of Organochlorine Pesticides in Spinach.

A new kind of glyoxal-urea-formaldehyde molecularly imprinted resin (GUF-MIR) was synthesized by a glyoxal-urea-formaldehyde (GUF) gel imprinting method with 4,4'-dichlorobenzhydrol as a dummy template. The obtained GUF-MIR was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) and applied as a selective adsorbent of miniaturized pipet tip solid-phase extraction (PT-SPE) for the separation and extraction of three organochlorine pesticides (dicofol (DCF), dichlorodiphenyl dichloroethane (DDD), and tetradifon) in spinach samples. The proposed pretreatment procedures of spinach samples involved only 5.0 mg of GUF-MIR, 0.7 mL of MeOH-H2O (1:1, v/v) (washing solvent), and 0.6 mL of cyclohexane-ethyl acetate (9:1, v/v) (elution solvent). In comparison with other adsorbents (such as silica gel, C18, NH2-silica gel, and neutral alumina (Al2O3-N)), GUF-MIR showed higher adsorption and purification capacity for DCF, DDD, and tetradifon in aqueous solution. The average recoveries at three spiked levels ranged from 89.1% to 101.9% with relative standard deviations (RSDs) ≤ 7.1% (n = 3). The presented GUF-MIR-PT-SPE method combines the advantages of molecularly imprinted polymers (MIPs), GUF, and PT-SPE and can be used in polar solutions with high affinity and selectivity to the analytes in complex samples.