Recent advances in microchip electrophoresis for analysis of pathogenic bacteria and viruses.

Life-threatening diseases, such as hepatitis B, pneumonia, tuberculosis, and COVID-19, are widespread due to pathogenic bacteria and viruses. Therefore, the development of highly sensitive, rapid, portable, cost-effective, and selective methods for the analysis of such microorganisms is a great challenge. Microchip electrophoresis (ME) has been widely used in recent years for the analysis of bacterial and viral pathogens in biological and environmental samples owing to its portability, simplicity, cost-effectiveness, and rapid analysis. However, microbial enrichment and purification are critical steps for accurate and sensitive analysis of pathogenic bacteria and viruses in complex matrices. Therefore, we first discussed the advances in the sample preparation technologies associated with the accurate analysis of such microorganisms, especially the on-chip microfluidic-based sample preparations such as dielectrophoresis and microfluidic membrane filtration. Thereafter, we focused on the recent advances in the lab-on-a-chip electrophoretic analysis of pathogenic bacteria and viruses in different complex matrices. As the microbial analysis is mainly based on the analysis of nucleic acid of the microorganism, the integration of nucleic acid-based amplification techniques such as polymerase chain reaction (PCR), quantitative PCR, and multiplex PCR with ME will result in an accurate and sensitive analysis of microbial pathogens. Such analyses are very important for the point-of-care diagnosis of various infectious diseases.

Synthesis of a Novel Electrochemical Probe for the Sensitive and Selective Detection of Biothiols and Its Clinical Applications.

The ability to estimate and quantify biothiols in biological fluids is very significant for attaining a detailed understanding of biothiols-related pathological diseases. Most of the developed methods for biothiols detection are not suitable for this purpose owing to their low sensitivity, poor selectivity, and long experimental procedures. In this study, a novel and simple structure electrochemical probe has been synthesized for the first time for the selective determination of biothiols. The developed probe is based on using 2,4-dinitrobenzenesulfonyl moiety (DNBS) as a selective recognition moiety for biothiols. The electrochemical probe was successfully fabricated through a facile one-step reaction between 2,4-dinitrobenzenesulfonyl chloride (DNBS-Cl) and p-aminophenol. The successful synthesis of the probe was confirmed by using different characterization techniques such as an NMR spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, and mass spectrometry. Biothiols can selectively cleave the DNBS moiety through an aromatic nucleophilic substitution (ANS) reaction within 10 min to release p-aminophenol, which is a highly electrochemical active molecule that can be selectively detected easily by cyclic voltammetry at low potential. The probe has been employed for the quantification of cysteine, glutathione, and homocysteine with a LOD of 1.50, 3.48, and 4.67 µM, respectively. Excellent recoveries have been achieved in the range of 95.44-98.71% for the determination of the total biothiols in the human plasma sample.

Recent trends and advancements in electrochemiluminescence biosensors for human virus detection.

Researchers are constantly looking to find new techniques of virus detection that are sensitive, cost-effective, and accurate. Additionally, they can be used as a point-of-care (POC) tool due to the fact that the populace is growing at a quick tempo, and epidemics are materializing greater often than ever. Electrochemiluminescence-based (ECL) biosensors for the detection of viruses have become one of the most quickly developing sensors in this field. Thus, we here focus on recent trends and developments of these sensors with regard to virus detection. Also, quantitative analysis of various viruses (e.g., Influenza virus, SARS-CoV-2, HIV, HPV, Hepatitis virus, and Zika virus) with a specific interest in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was introduced from the perspective of the biomarker and the biological receptor immobilized on the ECL-based sensors, such as nucleic acids-based, immunosensors, and other affinity ECL biosensors.

Spectrum, management and outcomes of structural and functional uropathies in children attending a tertiary care center in Karachi; Pakistan.

Causes and outcomes of children diagnosed with hydronephrosis in resource-limited countries with a low utilization of antenatal ultrasonography remain unexplored. We performed a retrospective, crosssectional study of all paediatric patients diagnosed with hydronephrosis and managed at a tertiary care center in Karachi, Pakistan between 2005 and 2010. Data relating to demographics, clinical features, etiologies and treatment modalities were systematically collected. Of a total of 234 cases (74.4% male), 83 (35.5%) and 42 (17.9%) were neonates and infants respectively. Congenital urinary tract pathologies were noted in 192(72.2%) patients, of which only 96(50%) had undergone foetal ultrasonography and 77(40.1%) first presented after the age of 1 year. At a median follow-up of 4 years, 24(12.5%) of these patients had evidence of renal dysfunction. Worse urologic outcomes in this study were most likely attributable to delayed diagnosis of congenital urinary tract abnormalities.

Wireless electrochemiluminescence with disposable minidevice.

Wireless electrochemiluminescence system based on the wireless energy transmission technique has been demonstrated for the first time. It has a disposable transmitter and a coiled energy receptor. The coiled energy receptor is smartly used as the electrode. The wireless electrochemiluminescence system has been used to detect hydrogen peroxide with good sensitivity, featuring advantages of easy manipulation, low cost, and small size. The handy and cheap wireless electrochemiluminescence device can use laptops as a power supply. It is promising for the development of portable or disposable electrochemiluminescence devices for various applications (e.g., such as point of care testing, field analysis, scientific research, and chemical education). These advantages enable one to integrate many wireless electrochemiluminescence minidevices with screen printing coiled electrode arrays in microwell plates and charge-coupled devices (CCD) cameras to develop electrochemiluminescence high-throughput screening systems with broad applications in clinical analysis, drug screening, and biomolecular interaction studies.

Regenerable sensor based on tris(4,7'-diphenyl-1,10-phenanthroline)ruthenium (II) for anodic and cathodic electrochemiluminescence applications.

Tris(4,7'-diphenyl-1,10-phenanthroline) ruthenium (II) dichloride [Ru(dpp)32+] was used for the first time to construct a regenerable electrochemiluminescence (ECL) sensor. The Ru(dpp)32+-modified carbon paste electrode (CPE) showed several unique features in comparison with commonly studied Ru(bpy)32+-modified electrodes. On the one hand, a quite reversible reduction peak was observed at -0.96 V where no obvious hydrogen evolution occured, enabling the sensitive detection of S2O82-. Moreover, our proposed S2O82- sensor showed a good linear range from 3 × 10-9 to 3 × 10-4 M with a detection limit of 2 nM, indicating higher sensitivity for the same analyte than previously reported ECL methods by about two orders of magnitude. On the other hand, the Ru(dpp)32+-modified electrode showed an irreversible oxidation peak because electrogenerated Ru(dpp)33+ is very reactive in aqueous solutions, while Ru(bpy)32+-modified electrode showed a reversible oxidation peak. Moreover, the present sensor showed a good linear range from 10-7 M to 10-3 M for oxalate with a detection limit of 60 nM. It detected oxalate in urine samples with nice recoveries. The regenerable ECL sensor presented good characteristics, such as low cost, simple fabrication procedure and fast response time. The Ru(dpp)32+ based regenerable sensor is an attractive alternative to Ru(bpy)32+-based regenerable sensor, as it can be used for both anodic and cathodic ECL analysis with high sensitivity in aqueous media.

Chemiluminescence of creatinine/H2O2/Co(2+) and its application for selective creatinine detection.

Creatinine is an important biomarker in clinical diagnosis and biomonitoring programs as well as urinary metabolomic/metabonomics research. Current methods are either nonselective, time consuming or require heavy and expensive instruments. In this study, chemiluminescence of creatinine with hydrogen peroxide has been reported for the first time, and its chemiluminescence is remarkably enhanced in the presence of cobalt ions. By utilizing these phenomena, we have developed a sensitive and selective chemiluminescence method for creatinine determination by coupling with flow injection analysis. The calibration curve is linear in the range of 1×10(-7)-3×10(-5)mol/L with a limit of detection (S/N=3) of 7.2×10(-8)mol/L, which is adequate for detecting creatinine in the clinically accepted range. The relative standard deviation for seven measurements of 3×10(-5)mol/L creatinine is 1.2%. The chemiluminescence method was then utilized to detect creatinine in human urine samples after simple dilution with water. It takes less than 1min each measurement and the recoveries for spiked urine samples were 100-103%. The interference study demonstrates that some common species in urine, such as amino acids, ascorbic acid and creatine, have negligible effects on creatinine detection. The present method does not use expensive instruments, enzymes and separation technique. This method has the advantages of sensitivity, selectivity, simplicity, rapidity, and low cost. It holds great promise for basic or comprehensive metabolic panel, drug screening, anti-dopping, and urinary metabolomic/metabonomics research.

Fabrication of biomembrane-like films on carbon electrodes using alkanethiol and diazonium salt and their application for direct electrochemistry of myoglobin.

Alkanethiols generally form self-assembled monolayers on gold electrodes and the electrochemical reduction of aromatic diazonium salts is a popular method for the covalent modification of carbon. Based on the reaction of alkanethiol with aldehyde groups covalently bound on carbon surface by the electrochemical reduction of aromatic diazonium salts, a new strategy for the modification of carbon electrodes with alkanethiols has been developed. The modification of carbon surface with aldehyde groups is achieved by the electrochemical reduction of aromatic diazonium salts in situ electrogenerated from a nitro precursor, p-nitrophenylaldehyde, in the presence of nitrous acid. By this way, in situ electrogenerated p-aminophenyl aldehyde from p-nitrophenylaldehyde immediately reacts with nitrous acid, effectively minimizing the side reaction of amine groups and aldehyde groups. The as-prepared alkanethiol-modified glassy carbon electrode was further used to make biomembrane-like films by casting didodecyldimethylammonium bromide on its surface. The biomembrane-like films enable the direct electrochemistry of immobilized myoglobin for the detection of hydrogen peroxide. The response is linear over the range of 1-600µM with a detection limit of 0.3µM.

Label-free signal-on ATP aptasensor based on the remarkable quenching of tris(2,2'-bipyridine)ruthenium(II) electrochemiluminescence by single-walled carbon nanohorn.

The quenching of electrochemiluminescence by single-walled carbon nanohorn has been demonstrated for the first time. Moreover, a sensitive, label-free, and signal-on electrochemiluminescence ATP aptasensor was developed using single-walled carbon nanohorn as both quencher and scaffold.