Quantification of methotrexate in plasma samples using highly fluorescent nanoparticles.

A novel amine-functionalized silica carbon polymer dots (APTES-CPDs)-based sensor was developed for methotrexate (MTX) detection. APTES-CPDs core-shell structure was synthesized via a one-step hydrothermal process and were employed as an optical sensor for MTX determination due to quenching effect of MTX on the fluorescence intensity of CPDs. Under optimum conditions, the developed sensor detects MTX in plasma samples in the dual linear ranges of 10 ng/mL to 2.0 µg/mL and 2.0 µg/mL to 50 µg/mL with a low limit of detections (LLOD)) of 10 ng/mL and 2.0 µg/mL, respectively. The obtained results are demonstrated the accuracy of the designed nanoprobe which is as high as to be used for the MTX detection in the routine therapeutic drug monitoring. In addition, the established nanoprobe shows significant specificity towards MTX compared to the co-administered drugs. Other advantages of this nanoprobe are its simple approach, high selectivity and sensitivity for MTX determination in plasma media which can approve the applicability of this MTX nanosensor in real samples.

Correction: Determination of aflatoxin M1 using an aptamer-based biosensor immobilized on the surface of dendritic fibrous nano-silica functionalized by amine groups.

Correction for 'Determination of aflatoxin M1 using an aptamer-based biosensor immobilized on the surface of dendritic fibrous nano-silica functionalized by amine groups' by Houman Kholafazad kordasht et al., Anal. Methods, 2019, 11, 3910-3919, DOI: 10.1039/C9AY01185D.

An innovative electrically conductive biopolymer based on poly(ß-cyclodextrin) towards recognition of ascorbic acid in real sample: Utilization of biocompatible advanced materials in biomedical analysis.

In this study, a sensitive platform was designed for the electrocatalytical oxidation and recognition of ascorbic acid (AA) based on poly(ß-cyclodextrin) modified glassy carbon electrode (p(ß-CD-GCE). Electropolymerization of ß-CD on the surface of GCE was performed on the potential range of -1 to 1.5 V. So, a novel biopolymer was prepared on the surface of GCE towards sensitive recognition of AA in human plasma samples. The developed platform has good sensitivity and accuracy for electrooxidation and detection of AA with lower limit of quantification (LLOQ) of 1 nM and linear range of 1 nM to 100 mM. Moreover, the designed electrochemical sensor was employed for the analysis of AA on human plasma samples with high sensitivity. Based on advantages of p(ß-CD) prepared by electropolymerization procedure (green, fast, homogeny, and efficient eletrocatalytical behaviour), this conductive biopolymer showed excellent analytical behaviour towards electrooxidation of AA. It is expected that the prepared polymeric interface is able to use in the analysis of biological species in clinical samples.

Electrochemical immunoplatform to assist in the diagnosis of oral cancer through the determination of CYFRA 21.1 biomarker in human saliva samples: Preparation of a novel portable biosensor toward non-invasive diagnosis of oral cancer.

In this study, a novel, low-cost, and flexible paper-based electrochemical immunosensor was developed for the bioanalysis of Cyfra 21.1 biomarker in human saliva samples by using stabilization of synthesis Ag nano-ink on the surface of paper using pen-on-paper technology. The employed electrochemical techniques for the evaluation of immunoplatform performance were differential pulse voltammetry and chronoamperometry. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 in human saliva specimens. Under the optimized conditions, the obtained linear range was from 0.0025 to 10 ng/mL, and the obtained LLOQ was 0.0025 ng/mL. The developed immunosensor is easy to prepare, sensitive, cost-effective, portable, and simple. So proposed immunoplatform can be an accomplished biodevice in clinical laboratories. The proposed paper-based immunosensor could be a hopefully new and cheap tool for the diagnosis of other biomarkers. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 biomarker in human saliva specimens.

Trifluralin recognition using touch-based fingertip: Application of wearable glove-based sensor toward environmental pollution and human health control.

Monitoring of herbicides and pesticides in water, food, and the environment is essential for human health, and this requires low-cost, portable devices for widespread deployment of this technology. For the first time, a wearable glove-based electrochemical sensor based on conductive Ag nano-ink was developed for the on-site monitoring of trifluralin residue on the surface of various substrates. Three electrode system with optimal thicknesses was designed directly on the finger surface of a rubber glove. Then, fabricated electrochemical sensor used for the direct detection of trifluralin in the range of 0.01 µM to 1 mM on the surface of tomato and mulberry leaves using square wave voltammetry (SWV) and difference pulse voltammetry technique. The obtained LLOQ was 0.01 µM, which indicates the suitable sensitivity of this sensor. On the other hand, this sensor is portable, easy to use, and has a high environmental capability that can be effective in detecting other chemical threats in the soil and water environment.

Sensitive aptasensing of ciprofloxacin residues in raw milk samples using reduced graphene oxide and nanogold-functionalized poly(amidoamine) dendrimer: An innovative apta-platform towards electroanalysis of antibiotics.

The constant need of humans and animals for food resources was led to overuse of antibiotics as vital medicines. In this regard, we are now facing major concern about the risks on the food safety and environment owing to their uncontrolled disposal. Hence, the progress of simple and sensitive approaches for fast monitoring of antibiotic levels is highly desirable. Here, we aimed to describe a new sensitive and easy-to use strategy based on electrochemical single off apta-assay toward ciprofloxacin (CFX). A novel interface using 3D Au-PAMAM/rGO have been designed via full electrochemically technique on the surface of glassy carbon electrodes (GCE) and evaluated with cyclic voltammetry method. Firstly, rGO with large amount of active functional groups as substrate was fabricated on the GCE electrode. Thereby, the 3D Au-PAMAM nanocomposite was synthesized and covalently electrodeposited onto the rGO-GCE modified surface. The structure and morphology of 3D Au-PAMAM were studied using UV-Vis spectroscopy, Field emission scanning electron microscopes (FE-SEM) and Transmission electron microscopy. Also, FE-SEM and Energy-dispersive X-ray spectroscopy (EDS) have been carry out to illustrate surface morphology of electrodes. The obtained results from square wave voltammetry, different pulse voltammetry, and chronoamperometry techniques implied that the suggested scaffold could be used as facile bio-device toward antibiotic detection with low limit of quantification (LLOQ) of 1 nM and a linear range of 1 µM-1 nM. Interestingly, the suggested aptasensor is successfully used to measure CFX residues in local and pasteurized milk samples. It can be deduced that Apt/rGO/3D Au-PAMAM/GCE as a novel biocompatible interface could offer suitable, cost-effective, reliable, rapid, and user-friendly sensing device for direct determination of CFX in real samples.

A stretchable glove sensor toward rapid monitoring of trifluralin: A new platform for the on-site recognition of herbicides based on wearable flexible sensor technology using lab-on-glove.

In this study, a flexible glove-based electrochemical sensor as a wearable point-of-use screening tool has been fabricated for defense and food security applications. To design the wearable glove-based sensor, we drew conductive patterns on the fingers of a rubber glove via gold@silver-modified graphene quantum dots (Au@Ag core-shell/graphene quantum dots [GQDs]) nano-ink with optimal thickness. Then, this platform is combined with a portable electrochemical analyzer for on-site detection of trifluralin pesticide in the range of 10 nM to 1 mM with the low limit of quantification (LLOQ) of 10 nM. The high efficiency and distinction of the trifluralin at specified concentrations in real leaf and apple samples were performed by simply touching with the glove and in spikes solution by immersing of fingertips. With their high sensitivity, selectivity, rapid, and easy operation pesticide analysis, these glove-embedded sensors can also be engaged in on-site monitor of other chemical threats and can be expanded to water and environmental samples.

Biomedical analysis of exosomes using biosensing methods: recent progress.

Exosomes are membrane-bound extracellular vesicles (EVs) that are produced in the endosomal compartments of most eukaryotic cells; they play important roles in intercellular communication in diverse cellular processes and transmit different types of biomolecules. Endocytic pathways release exosomes, which have diameters ranging from 50 to 200 nm. The unique functions of exosomes have been introduced as cancer bio-markers due to the cargo (protein, DNA and RNA) of external exosomes (tetraspanin) and internal exosomes (syntenin). The early detection of cancer by exosomes can be an excellent method for the treatment of cancer. Although detection methods based on exosomes are important, they require extensive sample purification, have high false-positive rates, and encounter labeling difficulties due to the small size of exosomes. Here, we have reviewed three major types of biosensors, namely, electrochemical biosensors, optical biosensors and electrochemiluminescence biosensors for the detection of exosomes released from breast, ovarian, pancreatic, lung, and cervical cancer cells. In addition, the importance of nanomaterials and their applications in the biomedical analysis of exosomes are discussed. Although exosomes can be used to identify various types of external and internal biomarkers by conjugating with recognition elements, most designed biosensors are based on CD9 and CD63. Therefore, the development of novel biosensors for the selective and sensitive detection of exosomes is a current challenge. We hope that this review will serve as a beneficial study for improving exosome detection in clinical samples.

Determination of aflatoxin M1 using an aptamer-based biosensor immobilized on the surface of dendritic fibrous nano-silica functionalized by amine groups.

Aflatoxins are potential food pollutants produced by fungi. Among them, aflatoxin M1 (AF M1) is the most toxic. A great deal of concern is associated with AF M1 toxicity. Aflatoxins are potential food pollutants produced by fungi. Among them, aflatoxin M1 (AF M1) is the most toxic. A great deal of concern is associated with AF M1 toxicity. In the present work, a novel aptamer-based bioassay was developed for monitoring aflatoxin M1 (AF M1) in real samples. A chitosan-modified graphene quantum dot (GQD-CS) nanocomposite was used as a biocompatible substrate coated with dendritic fibrous nanosilica functionalized by amine groups (KCC-1-NH2-Tb). Accordingly, an innovative biocompatible polymeric matrix was prepared for aptamer immobilization. The unique oligonucleotide of AF M1 (5'-ATC CGT CAC ACC TGC TCT GAC GCT GGG GTC GAC CCG GAG AAA TGC ATT CCC CTG TGG TGT TGG CTC CCG TAT) labelled by toluidine blue was immobilized on the engineered interface. Hence, a novel aptamer-based bioassay was formed for the highly sensitive quantitation of AF M1 using cyclic voltammetry and differential pulse voltammetry techniques. The structure and morphology of GQDs-CS/KCC-1-NH2-Tb was investigated by Fourier transform infrared spectroscopy, X-ray diffraction, atomic force and scanning electron microscopy and energy-dispersive X-ray spectroscopy. The toxicity tests, which were performed by MTT assays, revealed the biocompatible nature of KCC-1-NH2-Tb. The engineered aptasensor demonstrated excellent behaviour toward the determination of AF M1, where the low limit of quantification was 10 fM. The proposed aptamer-based bioassay was successfully used for the monitoring of AF M1 in milk samples. This work provides a beneficial reference for the sensing of other toxins in food/pharmaceutical assays and veterinary medicine.