A screen-printed carbon electrode modified with gold nanoparticles, poly(3,4-ethylenedioxythiophene), poly(styrene sulfonate) and a molecular imprint for voltammetric determination of nitrofurantoin.

A molecularly imprinted polymer (MIP) and a nanocomposite prepared from gold nanoparticles (AuNP) and poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) were deposited on a screen-printed carbon electrode (SPCE). The nanocomposite was prepared by one-pot simultaneous in-situ formation of AuNPs and PEDOT:PSS and was then inkjet-coated onto the SPCE. The MIP film was subsequently placed on the modified SPCE by co-electrodeposition of o-phenylenediamine and resorcinol in the presence of the antibiotic nitrofurantoin (NFT). Using differential pulse voltammetry (DPV), response at the potential of ~ 0.1 V (vs. Ag/AgCl) is linear in 1 nM to 1000 nM NFT concentration range, with a remarkably low detection limit (at S/N = 3) of 0.1 nM. This is two orders of magnitude lower than that of the control MIP sensor without the nanocomposite interlayer, thus showing the beneficial effect of AuNP-PEDOT:PSS. The electrode is highly reproducible (relative standard deviation 3.1% for n = 6) and selective over structurally related molecules. It can be re-used for at least ten times and was found to be stable for at least 45 days. It was successfully applied to the determination of NFT in (spiked) feed matrices and gave good recoveries. Graphical abstract Schematic representation of a voltammetric sensor for the determination of nitrofurantoin. The sensor is based on a screen-printed carbon electrode (SPCE) modified with an inkjet-printed gold nanoparticles-poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) nanocomposite and a molecularly imprinted polymer.

Enzyme-triggered PEGylated pDNA-nanoparticles for controlled release of pDNA in tumors.

Nanoparticle mediated functional delivery of plasmid DNA (pDNA) in vivo typically requires the formulation of pDNA-nanoparticles with a surface layer of stealth/biocompatibility polymer (usually poly(ethylene glycol) [PEG]). This PEG layer ensures the colloidal stability of pDNA-nanoparticles in biological fluids and minimizes nanoparticle interactions with the reticulo-endothelical system. Unfortunately, the presence of the PEG layer appears to contribute to a reduction in efficiency of functional delivery of pDNA once target cells are reached. For this reason, we have focused recent research efforts on "triggerable" nanoparticle systems. These are designed to be stable from the point of administration until a target site of interest is reached, then triggered for the controlled release of therapeutic agent payload(s) at the target site by changes in local endogenous conditions or through the application of some exogenous stimulus. Here, we describe investigations into the potential use of enzymes to trigger pDNA-mediated therapy through a process of enzyme-assisted nanoparticle triggerability. Our approach is to use PEG(2000)-peptidyl lipids with peptidyl moieties sensitive to tumor-localized elastase or matrix metalloproteinase-2 digestion, and from these prepare putative enzyme-triggered PEGylated pDNA-nanoparticles. Our results provide initial proof of concept in vitro. From these data, we propose that this concept should be applicable for functional delivery of therapeutic nucleic acids to tumor cells in vivo, although the mechanism for enzyme-assisted nanoparticle triggerability remains to be fully characterized.

Zingiber cassumunar Roxb. Essential Oil-Loaded Electrospun Poly(lactic acid)/Poly(ethylene oxide) Fiber Blend Membrane for Antibacterial Wound Dressing Application.

The essential oil from Zingiber cassumunar Roxb. (Plai) has long been used in Thai herbal remedies to treat inflammation, pains, sprains, and wounds. It was therefore loaded into an electrospun fibrous membrane for use as an analgesic and antibacterial dressing for wound care. The polymer blend between poly(lactic acid) and poly(ethylene oxide) was selected as the material of choice because its wettability can be easily tuned by changing the blend ratio. Increasing the hydrophilicity and water uptake ability of the material while retaining its structural integrity and porosity provides moisture balance and removes excess exudates, thereby promoting wound healing. The effect of the blend ratio on the fiber morphology and wettability was investigated using scanning electron microscopy (SEM) and contact angle measurement, respectively. The structural determination of the prepared membranes was conducted using Fourier-transform infrared spectroscopy (FTIR). The release behavior of (E)-1-(3,4-dimethoxyphenyl) butadiene (DMPBD), a marker molecule with potent anti-inflammatory activity from the fiber blend, showed a controlled release characteristic. The essential oil-loaded electrospun membrane also showed antibacterial activity against S. aureus and E. coli. It also exhibited no toxicity to both human fibroblast and keratinocyte cells, suggesting that the prepared material is suitable for wound dressing application.

Enzyme-triggered PEGylated siRNA-nanoparticles for controlled release of siRNA.

A key goal of our recent research efforts has been to develop novel 'triggerable nanoparticle' systems with real potential utility in vivo. These are designed to be stable from the point of administration until a target site of interest is reached, then triggered for the controlled release of therapeutic agent payload(s) at the target site by changes in local endogenous conditions or through the application of some exogenous stimulus. Here we describe investigations into the use of enzymes to trigger RNAi-mediated therapy through a process of enzyme-assisted nanoparticle triggerability. Our approach is to use PEG(2000)-peptidyl lipids with peptidyl moieties sensitive to tumour-localized elastase or matrix metalloproteinase-2 digestion, and from these prepare putative enzyme-triggered PEGylated siRNA-nanoparticles. Our results provide initial proof of concept in vitro. From these data, we propose that this concept should be applicable for functional delivery of therapeutic nucleic acids to tumour cells in vivo, although the mechanism for enzyme-assisted nanoparticle triggerability remains to be fully characterized.