Restricted Access Molecularly Imprinted Polymers for Biological Sample Preparation

Restricted access molecularly imprinted polymers (RAMIPs) have been efficiently used for the extraction of small organic molecules from untreated biological matrices (e.g. blood, plasma, serum, and milk). These materials have been obtained by modifying the external surface of conventional molecularly imprinted polymers (MIPs) with hydrophilic monomer grafting, crosslinked protein capsule or a combination of both. These sorbents aggregate the selectivity of MIPs with the ability to exclude macromolecules of restricted access materials (RAMs), being widely employed in solid phase extraction techniques, beyond their use in sensors. In this review, we discuss about the design and application of RAMIPs in biological sample preparation, emphasizing the future trends and remaining challenges of this technology for bioanalyses.

Surface Modification of Polyurethane Membrane with Various Hydrophilic Monomers and N-halamine: Surface Characterization and Antimicrobial Properties Evaluation

Reducing microbial infections associated with biomedical devices or articles/furniture noted in a hospital or outpatient clinic remains a great challenge to researchers. Due to its stability and low toxicity, the N-halamine compound has been proposed as a potential antimicrobial agent. It can be incorporated into or blended with the FDA-approved biomaterials. Surface grafting or coating of N-halamine was also reported. Nevertheless, the hydrophobic nature associated with its chemical configuration may affect the microbial interactions with the chlorinated N-halamine-containing substrate. In this study, a polymerizable N-halamine compound was synthesized and grafted onto a polyurethane surface via a surface-initiated atom transfer radical polymerization (SI-ATRP) scheme. Further, using the sequential SI-ATRP reaction method, different hydrophilic monomers, namely poly (ethylene glycol) methacrylate (PEGMA), hydroxyethyl methacrylate (HEMA), and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA), were also grafted onto the polyurethane (PU) substrate before the N-halamine grafting reaction to change the surface properties of the N-halamine-modified substrate. It was noted that the chains containing the hydrophilic monomer and the polymerizable N-halamine compound were successfully grafted onto the PU substrate. The degree of chlorination was improved with the introduction of a hydrophilic monomer, except the HEMA. All of these hydrophilic monomer-containing N-halamine-modified PU substrates demonstrated a more than 2 log CFU reduction after microbial incubation. In contrast, the surface modified with N-halamine only exhibited significantly less antimicrobial efficacy instead. This is likely due to the synergistic effects caused by the reduced chlorine content, as well as the reduced surface interactions with the microbes.

Synthesis of macro-RAFT agent containing M13-10 and its application in surface sizing agent

A novel macro-RAFT emulsifier was synthesized with S, S’-bis(α, α’-dimethyl-α”-acetic acid)-trithiocarbonate (BDATT), M13-10 (self-made emulsifier) and acrylate monomer, which was further used to prepare surface sizing agent. On the other hand, M13-10 was synthesized with iso-tridecanol polyoxyethylene ether, sodium methoxide and sulfamic acid as the starting materials. The hydrophilicity of macro-RAFT emulsifier and the performance of surface sizing agent were affected by BDATT used as the chain transfer agent and M13-10 as the hydrophilic monomer. So, the CMC and HLB of the emulsifier prepared with different M13-10 content and BDATT content, were compared, as well as the particle size of the prepared surface sizing agent, and the cobb, bursting resistance, tensile resistance, folding endurance and roughness of paper sized. The results reveal that surface sizing agent with macro-RAFT emulsifier of which the amount of M13-10 is 7 w% and the amount of BDATT is 2.5 w% demonstrates the best sizing effect on paper with the contact angle of 119°, the surface water absorption (cobb) of 48.8 g/m2, the bursting strength of 285 kPa, the folding endurance of 19 and the tensile strength of 59.6 kN/m.

Thermoresponsive dynamic BAB block copolymer networks synthesized by aqueous PISA in one-pot

The incorporation of neutral hydrophilic monomer units in the hydrophobic B blocks of BAB copolymers produces transient networks exhibiting a thermoresponsive behavior with a maximum of viscosity in water.

Fast-responsive temperature-sensitive hydrogels

Temperature fast-responsive and magnetic poly(N-isopropylacrylamide-co-acrylamide) (CMX-MNP-PNIPAm/Fe3O4) hydrogels were developed using carboxymethyl xylan (CMX) as a pore-forming agent and a NaCl solution as the reaction medium, followed by fabricating Fe3O4 nanoparticles in situ within the hydrogel matrix. It was found that NaCl played a role in the phase separation and was used as the electrolyte to shield CMX molecular chains. The obtained hydrogels exhibited a fast, temperature-responsive behavior, and the water retention was less than 15% for 1 min under 60 °C. The prepared hydrogels showed enhanced mechanical properties and magnetic properties due to the presence of Fe3O4 particles. The lower critical solution temperature of the hydrogels was in the range of 35 to 39 °C, which was acquired through adjusting the amount of hydrophilic monomer (AM). The magnetic and thermosensitive hydrogel had the attractive photothermal conversion ability and could be heated to 40 °C within 2 min, and to 69 °C within 7 min under near infrared irradiation.