New thiol-responsive mono-cleavable block copolymer micelles labeled with single disulfides.

Thiol-responsive symmetric triblock copolymers having single disulfide linkages in the middle blocks (called mono-cleavable block copolymers, ss-ABP(2)) were synthesized by atom transfer radical polymerization in the presence of a disulfide-labeled difunctional Br-initiator. These brush-like triblock copolymers consist of a hydrophobic polyacrylate block having pendent oligo(propylene oxide) and a hydrophilic polymethacrylate block having pendent oligo(ethylene oxide). Gel permeation chromatography and (1)H NMR results confirmed the synthesis of well-defined mono-cleavable block copolymers and revealed that polymerizations were well controlled. Because of amphiphilic nature, these copolymers self-assembled to form colloidally stable micelles above critical micellar concentration of 0.032 mg · mL(-1). In response to reductive reactions, disulfides in thiol-responsive micelles were cleaved. Atomic force microscopy and dynamic light scattering analysis suggested that the cleavage of disulfides caused dissociation of micelles to smaller-sized assembled structures in water. Moreover, in a biomedical perspective, the mono-cleavable block copolymer micelles are not cytotoxic and thus biocompatible.

Development of urinary albumin immunosensor based on colloidal AuNP and PVA.

The development of immunosensors with high sensitivity and specificity in detecting the pathogenic or physiologically relevant molecules in the body, offers a powerful opportunity in early diagnosis and treatment of diseases. In this study, we developed a new competitive immunosensor with employing antibody (Ab) labeled AuNP (Ab-AuNP) and PVA modified screen-printed carbon electrode (SPCE) surface to detect the urine albumin. Field emission scanning electron microscopy (FE-SEM) of modified electrode showed a suitable and stable attachment between HSA antigen- mAb and AuNP. Cyclic voltammetric (CV) method demonstrated that modification process was well performed. Electrochemical measurements including differential pulse voltammetry (DPV) and square wave voltammetry (SWV) were employed for quantitative antigen detection. The electrochemical measurements performed with other proteins mixed with samples demonstrated a high specificity and selectivity for this biosensor in detecting the HSA. In optimal conditions, the immunosensor could detect HSA in a high linear range (from 2.5 to 200 µg/mL) with a low detection limit of 25 ng/mL. This new strategy could be improved and applied to detect the other antigen.