The microbiological assay of vitamin B12

Development of a high-performance optical sensor for sensitive detection of cobalt ions in pharmaceutical, food, biological, and environmental samples

A re-generable optical chemical sensing film was created using a modified chitosan film that incorporates immobilized 4-(thiazol-2-yldiazenyl) benzene-1,3-diol (TDBD) for the detection of Co2+ in acidic aqueous solutions. Upon exposure to Co2+, the film's color shifted from yellowish green to red by forming a complex between Co2+ and TDBD. The sensor's complex was measured at 574 nm, a wavelength where the sensing membrane exhibited minimal background interference. The film exhibited its highest responsiveness to cobalt ions at pH 5.0. Two sample volumes were analysed: 2.5 mL with a Co2+ concentration range of 8.0-140 ng/mL, and 250 mL with a concentration range of 2.4-15.2 ng/mL. Both sample sizes produced linear calibration curves, with detection limits of 2.5 and 0.7 ng/mL, respectively. The relative standard deviation was 1.35 % for six separate films in a 100 ng/mL Co2+ solution, and 0.87 % for six individual films in a 10 ng/mL solution using 2.5 and 250 ng/mL, respectively. The sensing films demonstrated good stability over 30 days and were successfully used to determine Co2+ in pharmaceutical, food, environmental, and biological samples, yielding satisfactory results compared to the ICP-AES method.

A Comprehensive Study: Traditional and Cutting-Edge Analytical Techniques for the Biomarker Based Detection of the Micronutrients & POC Sensing Directions for Next-Generation Diagnostic

Micronutrient deficiency is wide spread and highly affects morbidity, mortality, and well-being of human beings. Micronutrient deficiency gradually manifests into diseases, which effects pathophysiology directly or indirectly. There is an imprecision in the diagnosis of micronutrient deficiency because of two causes; the selection of the standard biomarker and the diagnostic technique used. In appropriate diagnosis could increase the severity of the disorder. Instead of a single a combination of biomarkers can give more stringent results for micronutrient testing. Several traditional analytical techniques are used for diagnosis but HPLC, ELISA & LCMS/MS are most sensitive and reliable methods used by CLSIA-certified labs. However, these techniques require well-equipped, centralized laboratory facilities. The diagnostic era moves toward the Point of Care Testing (POCT), a boon in emerging diagnostics, breaking all paradigms of traditional analytical techniques. POCT led us toward the development of biosensors, which encompasses many techniques like paper-based sensors, microfluidic chip, wearable devices, and smartphone-assisted diagnostics, which become more popular diagnostic tools. This outlook summarizes the micronutrients like vitamins A, B5, B6, B7, B9, B12 C, D, and E and Minerals like iron, calcium, zinc, magnesium, and sodium; along with its biomarkers, analytical techniques, and point of care innovation in micronutrients.

Enhanced sensitivity and detection range of FRET-based vitamin B12 nanosensor

Vitamin B₁₂ (cobalamin) is a cobalt-containing compound that acts as an essential co-factor for various enzymes involved in the metabolic processes of the living cells. The constructed FRET Sensor for Vitamin Anemia Linked (SenVitAL) displayed marginal FRET efficiency. Here, we report the development of a molecular SenVitAL containing enhanced cyan fluorescent protein (ECFP) and venus as FRET pair to improve the FRET efficiency for optical imaging and screening of already developed sensor by our group. The sensor is the improved version of previously reported SenVitAL and consists of ECFP/venus as FRET pair instead of the originally used pair CFP/YFP. To increase the physiological range of vitamin B₁₂ measurement, affinity mutants were created. Compared to the wild type, SenVitAL-5 with W44Q mutation has higher affinity and displayed large dynamic detection range (0.10-480 µM) in response to vitamin B₁₂ binding. For cell-based monitoring and dynamic measurement of vitamin B₁₂ flux rates_, SenVitAL-5 was successfully expressed in cytosol of yeast and mammalian cells. Changes in the emission intensities of the two fluorophores were detected using confocal microscopy in both cell types in response to vitamin B₁₂. With the addition of 50 µM extracellular vitamin B₁₂ to the cells, the emission intensity of venus increased and that of ECFP decreased over the time. Furthermore, the results show that the variant SenVitAL-5 measures the vitamin B₁₂ in a concentration-dependent manner, showing the resulting increase in the FRET ratio and thus confirming its utility as an ideal fluorescent indicator for the detection of vitamin B₁₂ in eukaryotic systems in real time.