Vectorially Imprinted Hybrid Nanofilm for Acetylcholinesterase Recognition

Effective recognition of enzymatically active tetrameric acetylcholinesterase (AChE) is accomplished by a hybrid nanofilm composed of a propidium-terminated self-assembled monolayer (Prop-SAM) which binds AChE via its peripheral anionic site (PAS) and an ultrathin electrosynthesized molecularly imprinted polymer (MIP) cover layer of a novel carboxylate-modified derivative of 3,4-propylenedioxythiophene. The rebinding of the AChE to the MIP/Prop-SAM nanofilm covered electrode is detected by measuring in situ the enzymatic activity. The oxidative current of the released thiocholine is dependent on the AChE concentration from ≈0.04 × 10−6 to 0.4 × 10−6m. An imprinting factor of 9.9 is obtained for the hybrid MIP, which is among the best values reported for protein imprinting. The dissociation constant characterizing the strength of the MIP-AChE binding is 4.2 × 10−7m indicating the dominant role of the PAS-Prop-SAM interaction, while the benefit of the MIP nanofilm covering the Prop-SAM layer is the effective suppression of the cross-reactivity toward competing proteins as compared with the Prop-SAM. The threefold selectivity gain provided by i) the “shape-specific” MIP filter, ii) the propidium-SAM, iii) signal generation only by the AChE bound to the nanofilm shows promise for assessing AChE activity levels in cerebrospinal fluid

Sugarcane Bagasse Ash as a Catalyst Support for Facile and Highly Scalable Preparation of Magnetic Fenton Catalysts for Ultra-Highly Efficient Removal of Tetracycline

Sugarcane bagasse ash, which is waste from the combustion process of bagasse for electricity generation, was utilized as received as a catalyst support to prepare the magnetic sugarcane bagasse ash (MBGA) with different iron-to-ash ratios using a simple co-precipitation method, and the effects of NaOH and iron loadings on the physicochemical properties of the catalyst were investigated using various intensive characterization techniques. In addition, the catalyst was used with a low amount of H2O2 for the catalytic degradation of a high concentration of tetracycline (800 mg/L) via a Fenton system. The catalyst exhibited excellent degradation activity of 90.43% removal with good magnetic properties and high stabilities and retained good efficiency after four cycles with NaOH as the eluent. Moreover, the hydroxyl radical on the surface of catalyst played a major role in the degradation of TC, and carbon-silica surface of bagasse ash significantly improved the efficiencies. The results indicated that the MBGA catalyst shows the potential to be highly scalable for a practical application, with high performance in the heterogeneous Fenton system

Catalytically Active MIP Architectures

Molecularly imprinted polymers (MIPs) have been developed mostly for the specific binding of the target, mimicking the function of antibodies. In addition to these " plastic antibodies," completely synthetic catalysts have been created that mimic substrate conversion by enzymes. In this chapter, the following examples will be presented: (1) an esterolytic MIP for phenolic esters that is prepared using a transition state analogue as a template in an abzyme mimic; (2) MIPs using metal complexes and prosthetic groups, especially heme, in enzyme mimics; (3) a new MIP-enzyme architecture combining an enzyme containing an upper layer with a product-imprinted electropolymer on an amperometric electrode. The synergistic combination of the enzyme-catalyzed conversion of the drug aminopyrine with the MIP filter allows the interference-free measurement at a low electrode potential; and (4) protein-binding MIPs on top of a self-assembled monolayer (SAM) of an affinity ligand for the lectin concanavalin A (ConA) and the peroxidatic active hexameric tyrosine coordinated heme protein (HTHP). The oriented binding of the target protein to the SAM during formation of the MIP generates uniform binding sites. This is reflected by the high discrimination of similar lectins by the ConA-MIP and the realization of direct heterogeneous electron transfer and bioelectrocatalysis of peroxide reduction with the HTHP-MIP

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

One-Pot and Green Preparation of Phyllanthus emblica Extract/Silver Nanoparticles/Polyvinylpyrrolidone Spray-On Dressing

A spray-on wound dressing has many benefits, including easy and quick administration to broad and uneven wounds, better interface with the wound site, adhesion without additional dressing, and multiple applications in a portable package. By limiting direct contact with the wound site, such a design can prevent wound damage during treatment. This study revealed a simple, one-pot synthesis of spray-on wound dressing relying on polyvinylpyrrolidone solution incorporating silver nanoparticles as a broad-spectrum antibacterial agent and wound-healing antioxidant Phyllanthus emblica extract. Silver nanoparticles were synthesized in situ using Phyllanthus emblica extract as a biogenic reducing agent. Polyvinylpyrrolidone was employed as a film-forming agent to create an adhesive hydrogel-based dressing matrix to provide moisture and establish a shielding barrier for the wound bed as well as to regulate the release of fruit extract. In vitro tests revealed that the produced dressing film had a controlled release of the fruit extract, high antioxidant activity, and a good antibacterial action against S. aureus, P. aeruginosa, E. coli, and MRSA. Additionally, a biocompatibility study has shown that both human fibroblasts and keratinocytes are unaffected by the dressing film. Based on established findings, the current spray-on solution might be a potential option for antibacterial wound dressing

Electrospun poly(lactic acid) nanofiber mats for controlled transdermal delivery of essential oil from Zingiber cassumunar Roxb

A controlled release system of Plai ( Zingiber cassumunar Roxb.) oil based on electrospun poly(lactic) acid (PLA) nanofiber mat was successfully developed. The physicochemical properties of the nanofibers loaded with select amounts of oil (15%, 20%, and 30% wt) were characterized using various techniques, including a morphological study using scanning electron microscopy (SEM), structural determination using Fourier transform infrared spectrometry (FTIR) and x-ray diffraction (XRD), as well as thermal properties study using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The loading content and the entrapment efficiency of Plai oil within the fiber mats were evaluated and were found to be remarkably high, ensuring that PLA was an appropriate material for Plai oil loading. The ability of the nanofiber mats to release ( E )-1-(3,4-dimethoxyphenyl) butadiene (DMPBD) was also examined and the fiber mats showed controlled release characteristics. As the nanofiber mats have particularly high specific surface area with fully accessible and interconnected pore structures, a liquid medium with active ingredients will not be trapped in blind pores but can be fully released out of the fiber matrix. Furthermore, in vitro skin permeation of the active compound as well as a skin irritation were assessed using reconstructed human epidermis (EpiSkin ^TM ). It was found that DMPBD could efficiently penetrate through the skin model. Moreover, the nanofiber mats containing Plai oil also showed no skin irritation, indicating them as promising prototypes for medical applications