Novel synthesis and in vitro drug release of polymeric prodrug: Chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate.

A novel approach to synthesize chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate was developed. Chitosan-d4T monophosphate prodrug with a phosphoramidate linkage was efficiently synthesized through Atherton-Todd reaction. In vitro drug release studies in pH 1.1 and 7.4 indicated that chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate prefers to release the d4T 5'-(O-isopropyl)monophosphate than free d4T for a prolonged period. The results suggested that chitosan-O-isopropyl-5'-O-d4T monophosphate conjugate may be used as a sustained polymeric prodrug for improving therapy efficacy and reducing side effects in antiretroviral treatment.

Novel immunochromatographic assay based on Eu (III)-doped polystyrene nanoparticle-linker-monoclonal antibody for sensitive detection of Escherichia coli O157:H7.

Colloidal gold immunochromatographic assay (ICA) has poor sensitivity when used for Escherichia coli O157:H7 (E. coli O157:H7) detection. Eu (III)-doped polystyrene nanoparticle (EuNP) has a large range of stokes shift, long decay time, and wide excitation spectrum and narrow emission spectra. EuNP has been used as novel probe in ICA to improve sensitivity. In this study, carboxyl-modified EuNPs were prepared with different linkers. ICA based on EuNP, EuNP-6 carbon chain (CC) complex, EuNP-200CC complex, EuNP-1000CC complex, and EuNP-streptavidin (EuNP-SA) complex were systematically compared for the detection of E. coli O157:H7. Under optimized working conditions, the limits of detection (LOD) of EuNP-ICA, EuNP-6CC-ICA, EuNP-200CC-ICA, EuNP-1000CC-ICA, and EuNP-SA-ICA were 9.54 × 102, 1.59 × 102, 3.18 × 102, 2.98 × 102, and 1.08 × 102 colony-forming units (CFU) mL-1, respectively. The linear ranges of EuNP-ICA, EuNP-6CC-ICA, EuNP-200CC-ICA, EuNP-1000CC-ICA, and EuNP-SA-ICA were 6.36 × 102-1.59 × 105, 3.18 × 102-1.59 × 105, 6.36 × 102-1.59 × 105, 6.36 × 102-1.59 × 105, and 8.0 × 101-1.59 × 105 CFU mL-1, respectively. EuNP-SA-ICA exhibited the highest sensitivity and the widest linear range with good specificity, accuracy, and precision. It could be a promising analytical method for detecting E. coli O157:H7 in food samples. EuNP-SA-ICA may be a good model for detecting low concentrations of other food-borne pathogens.

Ultrabright and multicolorful fluorescence of amphiphilic polyethyleneimine polymer dots for efficiently combined imaging and therapy.

Multifunctional nanoparticles as theranostic tools hold great potential for its unique and efficient way to visualize the process of disease treatment. However, the toxicity of conventional fluorescent labels and difficulty of functionalization limit their widespread use. Recently, a number of amino-rich polymers have demonstrated high luminescent fluorescence but rarely showed potential for in vivo imaging due to their blue fluorescence. Here, a general route has been found to construct polymer-based multifunctional nanoparticles for combined imaging and drug delivering. The weak fluorescent polyethyleneimine (PEI) has been conjugated with hydrophobic polylactide as the amphiphilic PEI for construction of nanoparticles which showed bright and multicolor fluorescence with high drug loading capacity. The paclitaxel-loaded nanoparticles showed significant therapy effect in contrast to the free paclitaxel. Meanwhile, fluorescence imaging of the nanoparticles showed accumulation around tumor. These results demonstrate a new type of polymer-based multifunctional nanoparticles for imaging-guided drug delivery.