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Oak wilt caused by Bretziella fagacearum is an important disease of Quercus spp.; however, its diagnosis may be confused with damage resulting from other diseases, insects, or abiotic factors. Laboratory diagnosis is important in such situations and when disease control action is desired. PCR tests can provide accurate lab diagnosis within 2 days. Two variations of a simple DNA extraction protocol using sodium hydroxide (NaOH) were compared with that of the proprietary protocol of a commercially available kit (CK) for nested PCR to detect the pathogen in oak sapwood. High frequencies of pathogen detection (98 to 100% of 48 branch segments assayed) were found for northern pin oak using the two NaOH-based and the CK methods. Detection rates were similar but lower for bur oak (ranged from 58 to 79%) and white oak (ranged from 54 to 71%) regardless of DNA extraction method. Using our alternative DNA extraction protocols may reduce total time and cost of B. fagacearum detection in PCR-based diagnosis and other downstream applications.

Degarelix is a gonadotropin-releasing hormone (GnRH) receptor antagonist. Upon contact with physiological fluid, degarelix undergoes quick gelation and forms a depot at the site of injection providing sustained release. The molecular gelling kinetics is a critical physiochemical quality attribute of degarelix products that may impact drug delivery. However, high-resolution and drug substance (DS)-specific analytical methods for characterizing gelling kinetics of degarelix are still lacking. Accordingly, the current study focused on developing NMR-based methods to characterize in vitro initial aggregation of degarelix in Firmagon® drug product (DP). The high-precision real-time NMR method was demonstrated to quickly differentiate lot to lot differences in degarelix aggregation kinetics, and to reveal the effects of degarelix concentration, pH, salt, and temperature on the kinetics. The results could be useful for quality assurance of degarelix products and facilitate complex generic drug development. The real-time NMR method developed here could also be adopted to other complex DPs that have varied aggregation and release properties.

Drug release from microparticle-based topical gels may affect their bioavailability, safety and efficacy. This work sought to elucidate spatial distribution of the drug within the microparticle matrix and how this impacts the product's critical performance attributes. The purpose of this research was to inform the development of in vitro characterization approaches to support a demonstration of bioequivalence. Drug-free microparticles were loaded with tretinoin or drug-loaded microparticles were separated from purchased Retin-A Micro® (tretinoin) topical gel drug products. The resultant microparticles were analyzed for tretinoin content, drug loading efficiency, morphology, surface topography, surface pore size distribution, particle size distribution and tretinoin release. The solid-state characteristics and chemical interaction of tretinoin with the microparticles were also investigated. Microparticles loaded with tretinoin made in-house and those separated from Retin-A Micro® (tretinoin) topical gel were spherical, polydisperse and free of aggregates. The surface porosity of the microparticles was ∼19.8% with an average pore size of ∼327 nm. Microparticles loaded with tretinoin in-house were smaller in size and exhibited faster drug release than those separated from Retin-A Micro® (tretinoin) topical gel. Tretinoin release was found to increase with an increase in the drug loading. Based on XRD and DSC data, tretinoin was present in an amorphous state. The FTIR spectra indicated a disappearance of carbonyl band of microparticles and shifting of the hydroxyl band of tretinoin due to hydrogen bonding. The extent of drug loading and the solid-state interaction of tretinoin with the microparticles may be critical for drug release. Additional characterization of the drug products is necessary to understand the effect of the factors examined in this work on the bioavailability and efficacy of tretinoin gels.

α-Cyclodextrin (α-CD) has specific interactions with a number of important molecules including neurotoxins, pesticides, and hydrophobic drugs. Here, we describe the kinetics of a competitive inhibition of the interaction of α-CD with chromogenic polydiacetylene (PDA) liposomes. The competitive inhibition of α-CD with chromogenic PDA liposomes has already been used for sensing and detection purposes. Here we show that this mechanism can be successfully applied to characterize the reaction kinetics of α-CD with optically inactive compounds such as paraoxon neurotoxins via simple colorimetric changes. This method would enable easy characterisation of the interactions of α-CD when used as a drug delivery system or for drug solubilisation.

With increasing biomedical and engineering applications of selenium nanospheres (SeNS), new efficient methods are needed for the synthesis and long-term preservation of these nanomaterials. Currently, SeNS are mostly produced through the biosynthesis route using microorganisms or by using wet chemical reduction, both of which have several limitations in terms of nanoparticle size, yield, production time and long-term stability of the nanoparticles. Here, we introduce a novel approach for rapid synthesis and long-term preservation of SeNS on a solid microporous support by combining a mild hydrothermal process with chemical reduction. By using a natural sponge as a solid three-dimensional matrix for nanoparticle growth, we have synthesized highly monodisperse spherical nanoparticles with a wide size range (10–1000 nm) and extremely high yield in a relatively short period of time (1 h). Additionally, the synthesized SeNS can be stored and retrieved whenever needed by simply washing the sponge in water. Keeping the nanospheres in the support offers remarkable long-term stability as particles left on the sponge preserve their morphological and colloidal characteristics even after eight months of storage. Furthermore, this work reveals that SeNS can be used for efficient mercury capture from contaminated waters with a record-breaking mercury removal capacity of 1900 mg g−1.

Here we report a disposable, cost effective electrochemical paper-based sensor for the detection of both nitrate and mercury ions in lake water and contaminated agricultural runoff. Disposable carbon paper electrodes were functionalized with selenium particles (SePs) and gold nanoparticles (AuNPs). The AuNPs served as a catalyst for the reduction of nitrate ions using differential pulse voltammetry techniques. The AuNPs also served as a nucleation sites for mercury ions. The SePs further reinforced this mercury ion nucleation due to their high binding affinity to mercury. Differential pulse stripping voltammetry techniques were used to further enhance mercury ion accumulation on the modified electrode. The fabricated electrode was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electrochemistry techniques. The obtained results show that the PEG-SH/SePs/AuNPs modified carbon paper electrode has a dual functionality in that it can detect both nitrate and mercury ions without any interference. The modified carbon paper electrode has improved the analytical sensitivity of nitrate and mercury ions with limits of detection of 8.6µM and 1.0ppb, respectively. Finally, the modified electrode was used to measure nitrate and mercury in lake water samples.

We introduce an enzyme-free plasmonic immunoassay with a binary (all-or-none) response. The presence of a single pathogen in the sample results in a chemical cascade reaction leading to a large red to dark-blue colorimetric shift visible to the naked eye. The immediate and amplified response is initiated by a triggered breakdown of cysteine-loaded nanoliposomes and subsequent aggregation of plasmonic gold nanoparticles. Our approach enabled visual detection of a single-digit live pathogen of Salmonella, Listeria, and E. coli O157 in water and food samples. Furthermore, the assay allowed a naked-eye detection of target antibody concentrations as low as 6.7 attomolar (600 molecules in 150 μL); six orders of magnitude lower than conventional enzyme-linked immunosorbent assay (ELISA).

Remarkable efforts have been dedicated to paper-based chemosensors and biosensors over the last few years, mainly driven by the promise of reaching the best trade-off between performance, affordability and simplicity. Because of the low-cost and rapid prototyping of these sensors, recent research has been focused on providing affordable diagnostic devices to the developing world. The recent progress in sensitivity, multi-functionality and integration of microfluidic paper-based analytical devices (µPADs), increasingly suggests that this technology is not only attractive in resource-limited environments but it also represents a serious challenger to silicon, glass and polymer-based biosensors. This review discusses the design, chemistry and engineering aspects of these developments, with a focus on the past few years.