Streptomycin-imprinted silica microspheres were prepared by combining a surface molecular-imprinting technique with the sol-gel method. A mixture of tetrahydrofuran, ethanol, and water (6:1:1, v/v/v) was selected as dispersing solvent while 3-aminopropyltriethoxysilane and triethoxyphenylsilane acted as functional monomers, and tetraethyl orthosilicate as a cross-linker. Characterization of the molecularly imprinted polymers was conducted using scanning electron microscope and dynamic binding experiments. As compared to the nonimprinted polymers, the imprinted polymers exhibited a higher degree of saturated adsorption volume up to 26.3 mg/g, and better selectivity even in an aqueous solution with interfering compounds, including dihydrostreptomycin, neomycin, and tetracycline. The adsorption ability and selectivity were observed to be influenced by the mole ratio of 3-aminopropyltriethoxysilane and triethoxyphenylsilane. Feasibility of the polymers to be used for actual application was also evaluated with spiked samples, indicating great potential for large-scale applications. Moreover, the streptomycin-imprinted polymers can be repeatedly used for 12 cycles without losing original performance, which is beneficial for commercial use.

Macroporous poly(N-isopropylamide-co-acrylamide) [P(NIPAAm-co-AAm)] hydrogels were successfully prepared by a two-step polymerization method. The initial polymerization was carried out at 18 °C with different duration, followed by freezing polymerization at –18 °C for 24 h. The results showed that the immediate performance of freezing polymerization played a dominant role in the final properties of the P(NIPAAm-co-AAm) hydrogels. The thermoresponsive rate and mechanical strength of the hydrogels were drastically changed by freezing the reaction mixture after 3 min of the first polymerization (PNA-3). Scanning electron microscopy (SEM) studies revealed that the hydrogel frozen after 3 min exhibited the most highly interconnected porous structures and the largest pore size. These open pore structures were very useful to accelerate the responsive rate of the hydrogels. In vitro BSA (bovine serum albumin) release from the hydrogel PNA-3 exhibited relatively small initial burst release followed by a steady release. Such results demonstrated that the P(NIPAAm-co-AAm) hydrogels frozen before gelation have the potential to be applicated for delivering proteins.

In this study, a novel heparin-immobilized polyethersulfone (PES) was synthesized. PES was initially sulfonated with chlorosulfonic acid and then 1,6-hexanediamine was grafted to the SO₃H groups of sulfonated PES, which subsequently reacted with heparin through a covalent bond by using (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) as catalyst. The hydrophobic/hydrophilic property was characterized by measuring the water contact angle. The data shows decline from 62.29° ± 1.2° to 47.86° ± 0.3° for water and 86.79° ± 0.8° to 68.34° ± 1.0° for glycerol, which indicates an enhancement of hydrophilicity. Plasma hemolysis assay shows a comparatively low hemolysis ratio of 1.04%, which is below permissible limit of 5%. A higher content of dissociated blood cells and Ca²⁺ concentration was found in red blood cell counting and coagulation factor IV test in heparinized PES. Plasma recalcification time of 360 s also offers positive evidence that heparinized PES seems to have a good anticoagulation property. This new heparin-immobilized PES biomaterials may have the potential for biomedical applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008