Identifying citrus limonoids as a potential fusion inhibitor of DENV-2 virus through its in silico study and FTIR analysis.

Dengue virus type 2 (DENV-2) is an arthropod-borne deadly RNA human pathogen transmitted through the mosquito Aedes. The DENV-2 roots viral infection by facilitating entry with its envelope glycoprotein to the receptor protein Dendritic-cell-specific ICAM3-grabbing non-integrin (DC-SIGN) through membrane fusion. Here, an organizational path is reported for inhibiting the transition due to fusion activation and by blocking the residues of the DC-SIGN-E-Glyco protein complex through citrus limonoids with its antiviral effect. Based on lower binding affinity obtained with E-glycoprotein, and based on ADMET and drug-likeness study, limonin was selected as having effective interaction with DC-SIGN-E-glycoprotein complex in comparison to other citrus limonoids. The FTIR spectra performed with the limonin-E-glycoprotein sample provide evidence of hydrogen bond formation that indicates the formation of a strong limonin-E-glycoprotein conjugate. Further, the strong physical interaction between DC-SIGN and small limonin molecules in comparison to that of E-glyco with DC-SIGN assures the development of immunity against DENV-2. Supplementary Information: The online version contains supplementary material available at 10.1007/s40203-024-00207-2.

Rapid diagnosis of COVID-19 using disposal paper capacitive sensor.

Accurate and rapid detection and isolation become indispensable to restrict the spread of COVID-19. Since the start of COVID-19 pandemic in December 2019, many indisposal diagnostic tools are being developed incessantly. Out of all presently used tools, the gold standard rRT- PCR tool having very high sensitivity and specificity is a time consuming complicated molecular technique having requirements of special expensive equipment. Here, the main focus of this work is to develop rapid disposal paper capacitance sensor having simple and easy detection. We discovered a strong interaction between limonin and Spike-glycoprotein of SARS-COV-2 in comparison to its interaction with other similar viruses such as HCOV-OC43, HCOV-NL63, HCOV-HKU1, Influenza B and A viruses. The antibody free capacitive sensor having comb electrode structure was fabricated on whatman paper with drop coating of limonin (extracted using green method from pomelo seeds) and calibrated with known swab samples. The Blind test with unknown swab samples shows high sensitivity of 91.5% and high specificity of 88.37%. Requiring low sample volume and detection time and using biodegradable materials in the sensor fabrication assure the potential application as a point of care disposal diagnostic tool.

Onsite fish quality monitoring using ultra-sensitive patch electrode capacitive sensor at room temperature.

Fish freshness plays a vital role in the fish industry and also affects human health from a nutrition point of view. Here, an Au metal patch electrode capacitive sensor is introduced for rapid and accurate detection of volatile gases generated from raw fish to determine its freshness status. The MIS structured sensor was fabricated on a silicon substrate using Ag-SnO2 as sensing material over SiO2 layer and Au as a metal electrode. The calibration of the sensor was carried out with known composition of volatile gases (NH3, TMA, DMA and H2S) in the ppb-ppm regime. Our sensor using the proposed technique delivers sensor response to raw fish within 4 min, reflecting its freshness status in comparison to the TVB-N and TVC method which takes many hours to complete involving many sophisticated steps. The sensor response to volatile gases from Rohu (Labeo Rohita), Tilapia (Oreochromis Niloticus) and Illish (Tenualosa Ilisha) obtained by using our developed sensor system at 20 °C, 25 °C, and 30 °C, shows high correlation with TVB-N and TVC results. The acceptance limit for safe consumption of Tilapia, Rohu, and Illish at 30 °C was found to be 11 h, 12.5 h, and 10 h of storage time respectively. The result in this work assures a portable low-cost sensor for onsite monitoring of fish freshness at room temperature.

Meat quality assessment using Au patch electrode Ag-SnO2/SiO2/Si MIS capacitive gas sensor at room temperature.

An Au patch electrode Ag-SnO2/SiO2/Si MIS capacitive sensor equipped with a microcontroller was designed and developed to sense low concentration (ppb to ppm regime) of volatiles (NH3, TMA, ethanol, and H2S) generated from chicken meat spoilage at room temperature. The quality threshold or the acceptance limit for consumption of chicken meat samples stored at 4 °C, 15 °C and 25 °C using our proposed technique was found to be 105 h, 48 h, and 17 h respectively, highly correlated with TVB-N, TVC, pH and sensory evaluation analysis. When these well established standard methods (TVB-N, TVC and pH analysis) take many hours to complete the analysis involving many complicated steps, our fabricated sensor takes 55 sec to deliver sensing response reflecting the meat spoilage status. The sensor calibrated with our compact technique promises portable and inexpensive onsite rapid and accurate quality assessment of meat spoilage at room temperature.

Variable optical attenuator using thermo-optic two-mode interference device with fast response time.

A thermo-optic two-mode interference (TMI) waveguide structure with a silicon trench and heat-insulating grooves in both sides of the core has been proposed for a variable optical attenuator (VOA) with fast response time. Thermal analysis of the proposed thermo-optic TMI waveguide structure with a silicon oxinitride (SiON) core has been performed by using the implicit finite difference method. The heating power required to achieve the attenuated power of approximately -25.5 dB for a VOA with a silicon trench is 460 mW , which is approximately 1.8 times less than that of a VOA without a silicon trench. The response time is estimated as approximately 98 micros, which is faster than the response time of the existing VOA.