Novel nandrolone aptamer for rapid colorimetric detection of anabolic steroids.

The illicit use of anabolic androgenic steroids (AAS) as performance-enhancing drugs remains a global issue threatening not only the credibility of competitive sports but also public health due to the well-documented adverse effects they elicit. AAS abuse is not restricted only to professional sports, but also extends to recreational athletes and adolescents as well as in livestock production as growth-promoting agents. Testosterone and nandrolone are among the AAS most frequently exploited.

Low-Cost Platform for Multiplexed Electrochemical Melting Curve Analysis.

Detection and identification of single nucleotide polymorphisms (SNPs) have garnered increasing interest in the past decade, finding potential application in detection of antibiotic resistance, advanced forensic science, as well as clinical diagnostics and prognostics, moving toward the realization of personalized medicine. Many different techniques have been developed for genotyping SNPs, and ideally these techniques should be rapid, easy-to-use, cost-effective, flexible, scalable, easily automated, and requiring minimal end-user intervention. While high-resolution melting curve analysis has been widely used for the detection of SNPs, fluorescence detection does not meet many of the desired requirements, and electrochemical detection is an attractive alternative due to its high sensitivity, simplicity, cost-effectiveness, and compatibility with microfabrication.

A biophotoelectrode based on boronic acid-modified Chlorella vulgaris cells integrated within a redox polymer.

Green microalgae are gaining attention in the renewable energy field due to their ability to convert light into energy in biophotovoltaic (BPV) cells. The poor exogenous electron transfer kinetics of such microorganisms requires the use of redox mediators to improve the performance of related biodevices. Redox polymers are advantageous in the development of subcellular-based BPV devices by providing an improved electron transfer while simultaneously serving as immobilization matrix.

Aptamer Sandwich Assay for the Detection of SARS-CoV-2 Spike Protein Antigen.

The novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) emerged at the end of 2019, resulting in the ongoing COVID-19 pandemic. The high transmissibility of the virus and the substantial number of asymptomatic individuals have led to an exponential rise in infections worldwide, urgently requiring global containment strategies. Reverse transcription-polymerase chain reaction is the gold standard for the detection of SARS-CoV-2 infections.

Hybrid Antibody-Aptamer Assay for Detection of Tetrodotoxin in Pufferfish.

The marine toxin tetrodotoxin (TTX) poses a great risk to public health safety due to its severe paralytic effects after ingestion. Seafood poisoning caused by the consumption of contaminated marine species like pufferfish due to its expansion to nonendemic areas has increased the need for fast and reliable detection of the toxin to effectively implement prevention strategies. Liquid chromatography-mass spectrometry is considered the most accurate method, although competitive immunoassays have also been reported.

Aptasensors for mycotoxin detection: A review.

Mycotoxins are toxic compounds produced by fungi, which represent a risk to the food and feed supply chain, having an impact on health and economies. A high percentage of feed samples have been reported to be contaminated with more than one type of mycotoxin. Systematic, cost-effective and simple tools for testing are critical to achieve a rapid and accurate screening of food and feed quality.

Gold nanoparticle aptamer assay for the determination of histamine in foodstuffs.

The development of a gold nanoparticle aptamer assay is persued for rapid and sensitive determination of histamine in foodstuffs, which could be deployed for on-site use. The assay is based on a histamine-specific aptamer and gold nanoparticles and the salt-induced aggregation of the particles in the presence of histamine indicated by the color change from red to blue. Gold nanoparticle size, salt type, and concentration as well as aptamer concentration were optimized, and using optimum conditions, a limit of detection of 8 nM (~ 0.

Yersinia pestis detection using biotinylated dNTPs for signal enhancement in lateral flow assays.

Due to the extreme infectivity of Yersinia pestis it poses a serious threat as a potential biowarfare agent, which can be rapidly and facilely disseminated. A cost-effective and specific method for its rapid detection at extremely low levels is required, in order to facilitate a timely intervention for containment. Here, we report an ultrasensitive method exploiting a combination of isothermal nucleic acid amplification with a tailed forward primer and biotinylated dNTPs, which is performed in less than 30 min.

Pediatric glioblastoma target-specific efficient delivery of gemcitabine across the blood-brain barrier via carbon nitride dots.

Pediatric glioblastomas are known to be one of the most dangerous and life-threatening cancers among many others regardless of the low number of cases reported. The major obstacles in the treatment of these tumors can be identified as the lack of prognosis data and the therapeutic requirement to be able to cross the blood-brain barrier (BBB). Due to this lack of data and techniques, pediatric patients could face drastic side effects over a long-time span even after survival.

Tyrosinase enzyme Langmuir monolayer: Surface chemistry and spectroscopic study.

This study investigates the surface chemistry properties of the tyrosinase enzyme Langmuir monolayer at air-aqueous interface using sodium chloride in the subphase to induce the surface activity of the enzyme. Investigation of surface packing and stability of the tyrosinase Langmuir monolayer were performed using surface chemistry experiments while spectroscopic analysis was done to study enzyme conformation. It was found that the tyrosinase enzyme forms a fluid film at air-aqueous interface with good stability as shown by compression-decompression cycles experiments and stability measurements at various surface pressures.

One-Pot SELEX: Identification of Specific Aptamers against Diverse Steroid Targets in One Selection.

Aptamers are well-established biorecognition molecules used in a wide variety of applications for the detection of their respective targets. However, individual SELEX processes typically performed for the identification of aptamers for each target can be quite time-consuming, labor-intensive, and costly. An alternative strategy is proposed herein for the simultaneous identification of different aptamers binding distinct but structurally similar targets in one single selection.

Nontoxic amphiphilic carbon dots as promising drug nanocarriers across the blood-brain barrier and inhibitors of β-amyloid.

The blood-brain barrier (BBB) is a main obstacle for drug delivery targeting the central nervous system (CNS) and treating Alzheimer's disease (AD). In order to enhance the efficiency of drug delivery without harming the BBB integrity, nanoparticle-mediated drug delivery has become a popular therapeutic strategy. Carbon dots (CDs) are one of the most promising and novel nanocarriers.

Duplex PCR-ELONA for the detection of pork adulteration in meat products.

In this work, a duplex PCR-Enzyme Linked Oligonucleotide Assay (ELONA) is reported for the sensitive and reliable detection of pork adulteration in beef and chicken products, two of the most widely consumed meat types in the world. The strategy relies on the use of species-specific tailed primers for duplex amplification and simple dilution of the PCR reactions for direct colorimetric detection via hybridization, eliminating the need for any other post-amplification steps. A high sensitivity was achieved, with as low as 71-188 pg of genomic DNA able to be detected using mixtures of control DNA from each species.

Carbon dots and gold nanoparticles based immunoassay for detection of alpha-L-fucosidase.

Hepatocellular carcinoma (HCC) is among the leading causes of mortality in the world. The detection of HCC in its early stage is the key for early treatment and thus the improvement of the chances of survival. Among the various methods of HCC screening, assays based on the detection of biomarker that is specific to HCC such as alpha-l-fucosidase (AFU) have been regarded as the most prominent methods.

Duplex Lateral Flow Assay for the Simultaneous Detection of Yersinia pestis and Francisella tularensis.

High-risk pathogens such as Francisella tularensis and Yersinia pestis are categorized as highly hazardous organisms that can be used as biological weapons. Given the extreme infectivity of these potential biowarfare agents, a rapid, sensitive, cost-effective, and specific method for their detection is required. Here, we report the multiplexed amplification detection of genomic DNA from Francisella tularensis and Yersinia pestis.

Aptamer Selection against a Trichomonas vaginalis Adhesion Protein for Diagnostic Applications.

Trichomoniasis, caused by Trichomonas vaginalis, is the leading nonviral sexually transmitted infection worldwide. We report the selection of a DNA aptamer against a T. vaginalis adhesion protein, AP65, using a microtiter plate-based in vitro combinatorial chemistry process termed systematic evolution of ligands by exponential enrichment.

Alpha-l-Fucosidase Immunoassay for Early Detection of Hepatocellular Carcinoma.

Detection of alpha-l-fucosidase has been shown to have relevance in diagnosing hepatocellular carcinoma. Few assays have been developed to measure this enzyme, with most relying on colorimetric techniques involving the enzyme's kinetics. While these assays are facile and quick, the sensitivity is not always sufficient for early tumor detection.

Aptatope mapping of the binding site of a progesterone aptamer on the steroid ring structure.

In this work we report the mapping of the binding site of the only progesterone aptamer published to date, in an approach referred to as aptatope mapping. By linking the binding data obtained from microscale thermophoresis analysis to the structural differences on the ring structure of a range of steroids, we elucidated the moieties involved in aptamer-progesterone binding. This approach can be further exploited for the characterization of aptamer specificity and ultimately facilitate the development of aptamer-based assays depending on the desired specificity.

"Dark" carbon dots specifically "light-up" calcified zebrafish bones.

Because accidents, disease and aging compromise the structural and physiological functions of bones, the development of an in vivo bone imaging test is critical to identify, detect and diagnose bone related development and dysfunctions. Recent advances in fluorescence instrumentation offer a new alternative for traditional bone imaging methods. However, the development of new in vivo bone imaging fluorescence materials has significantly lagged behind.

Study of the Alpha-l-Fucosidase Langmuir Monolayer at the Air-Water Interface.

Alpha-l-fucosidase is a known biomarker for hepatocellular carcinoma that has shown great potential in diagnostics. Most of the focus for this enzyme has been on the free form found in serum; however, little is known of the properties of the minor portion of membrane-bound alpha-l-fucosidase. To better understand the properties of membrane-bound alpha-l-fucosidase, this enzyme was surveyed at the air-water interface.

Ultrasensitive, rapid and inexpensive detection of DNA using paper based lateral flow assay.

Sensitive, specific, rapid, inexpensive and easy-to-use nucleic acid tests for use at the point-of-need are critical for the emerging field of personalised medicine for which companion diagnostics are essential, as well as for application in low resource settings. Here we report on the development of a point-of-care nucleic acid lateral flow test for the direct detection of isothermally amplified DNA. The recombinase polymerase amplification method is modified slightly to use tailed primers, resulting in an amplicon with a duplex flanked by two single stranded DNA tails.

The Thermodynamic and Kinetic Properties of 2-Hydroxypyridine/2-Pyridone Tautomerization: A Theoretical and Computational Revisit.

The gas-phase thermal tautomerization reaction between 2-hydroxypyridine (2-HPY) and 2-pyridone (2-PY) was investigated by applying 6-311++G** and aug-cc-pvdz basis sets incorporated into some density functional theory (DFT) and coupled cluster with singles and doubles (CCSD) methods. The geometrical structures, dipole moments, HOMO-LUMO energy gaps, total hyperpolarizability, kinetics and thermodynamics functions were monitored against the effects of the corrections imposed on these functionals. The small experimental energy difference between the two tautomers of 3.

UV excitations of halons.

In the present study, we examined the UV excitations of a newly introduced molecular set, Halons-9, composed of nine gaseous halon molecules. The performance of the density functional-based multi-reference configuration interaction method (DFT/MRCI) and time-dependent density functional theory with CAM-B3LYP functional (TD-CAM-B3LYP) in the computation of singlet and triplet excited states of this set was evaluated against coupled-cluster with singles and doubles (CCSD). Excited states up to the corresponding ionization limits, including both localized and delocalized excitations, have been benchmarked.