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The outbreak rate of human coronaviruses (CoVs) especially highly pathogenic CoVs is increasing alarmingly. Early detection of these viruses allows treatment interventions to be provided more quickly to people at higher risk, as well as helping to identify asymptomatic carriers and isolate them as quickly as possible, thus preventing the disease transmission chain. The current diagnostic methods such as RT-PCR are not ideal due to high cost, low accuracy, low speed, and probability of false results. Therefore, a reliable and accurate method for the detection of CoVs in biofluids can become a front-line tool in order to deal with the spread of these deadly viruses. Currently, the nanomaterial-based sensing devices for detection of human coronaviruses from laboratory diagnosis to point-of-care (PoC) diagnosis are progressing rapidly. Gold nanoparticles (AuNPs) have revolutionized the field of biosensors because of the outstanding optical and electrochemical properties. In this review paper, a detailed overview of AuNP-based biosensing strategies with the varied transducers (electrochemical, optical, etc.) and also different biomarkers (protein antigens and nucleic acids) was presented for the detection of human coronaviruses including SARS-CoV-2, SARS-CoV-1, and MERS-CoV and lowly pathogenic CoVs. The present review highlights the newest trends in the SARS-CoV-2 nanobiosensors from the beginning of the COVID-19 epidemic until 2022. We hope that the presented examples in this review paper convince readers that AuNPs are a suitable platform for the designing of biosensors. [ABSTRACT FROM AUTHOR]

The aim of this study is to develop an immunoaffinity sensor based on piezoelectric crystals for human serum albumin (HSA) detection in aqueous media. Quartz crystals were treated with ethylene diamine (EDA) plasma in a glow-discharge apparatus in order to substitute amino groups on their surfaces. Then anti-HSA antibodies were immobilized via these amino groups by using glutaraldehyde (GA) as cross-linker. Immobilization of the antibody on the quartz crystal was examined for different pH, antibody concentration and treatment time. The optimum conditions for anti-HSA immobilization were evaluated by the measurements of the activity of the surface against HSA. The optimum values of pH, antibody concentration and treatment time were found 6.2, 0.15 mg/ml and 2 h, respectively. For detection of HSA into the solution, two methods were used. In the first (dip and dry) method, the frequency shifts were measured in air after the 1 h interaction of the anti-HSA immobilized crystals with HSA solution. In the other (direct) method, the frequency shifts were followed continuously for 60 min. while the probe was immersed in the HSA solution. An increase for the frequency shifts was observed with increasing of HSA concentration of 16–128 μg/ml. Both the immobilization and antibody-interaction conditions were found important on the extend of these specific interaction. The relations between the HSA concentrations and frequency shifts were exponential in both methods. [Copyright &y& Elsevier]

Herein, for the first time a visible-light-driven photoelectrochemical (PEC) aptasensor for shrimp tropomyosin determination was fabricated by using graphitic carbon nitride (g-C 3 N 4 ) and titanium dioxide (TiO 2 ) as photoactive nanomaterials, ascorbic acid (AA) as electron donor and ruthenium (III) hexaammine (Ru(NH 3 ) 6 3+ ) as signal enhancer. The surface of an ITO electrode was first modified with g-C 3 N 4 , TiO 2 , and polyethyleneimine (PEI) and then the amine terminal aptamer TROP probe was attached to PEI by the use of glutaraldehyde (GA) as cross-linker. After that, Ru(NH 3 ) 6 3+ was adsorbed on aptamer to enhance the photocurrent signal. The principle of proposed PEC aptasensor is based on the formation of a selective complex between tropomyosin and immobilized aptamer TROP probe on the surface of ITO/g-C 3 N 4 -TiO 2 /PEI/aptamer TROP -Ru(NH3) 6 +3 . After the incubation of tropomyosin with TROP aptamer probe, the photocurrent signal decreased due to releasing adsorbed Ru(NH 3 ) 6 3+ on aptamer and preventing AA from scavenging photogenerated holes to the photoactive modified electrode. Under the optimized conditions, the fabricated PEC aptasensor was used for the determination of shrimp tropomyosin in the concentration range of 1–400 ng mL −1 with a limit of detection of 0.23 ng mL −1 . The proposed PEC aptasensor exhibited high selectivity, sensitivity, and good stability. [ABSTRACT FROM AUTHOR]