Antibody-labelled gold nanoparticles synthesized by laser ablation to detect SARS-CoV-2 antigen spike.

Background and purpose: Rapid detection test via lateral flow immunoassay (LFIA) is employed as an alternate method to detect Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Gold nanoparticles (AuNPs), a vital component of LFIA, can be synthesized by laser ablation technique. This intense laser radiation may result in monodisperse gold nanoclusters, which are impurity-free and demonstrate innovative biocompatible surface chemistry. In this current research, laser-ablated AuNPs are produced and coupled with an anti-spike SARS-CoV-2 monoclonal antibody (mAb) generated in our prior study. Experimental approach: The AuNPs from 30,000 shots of laser ablation exhibited a robust red color with a maximum absorbance peak at 520 nm. The performance of AuNPs-mAb conjugates as a signal reporter was then evaluated in half-stick LFIA. Key results: The size distribution of AuNPs shows a relatively monodisperse and unimodal distribution with average particle diameters of 44.77 nm and a surface potential of -38.5 mV. The purified anti-spike mAb SARS-CoV-2 yielded two protein bands, representing the mAb heavy chain at 55 kDa and its light chain at 25 kDa. The immobilization of anti-spike mAb onto the surface of AuNPs revealed that 25 g/ml of mAb at phosphate buffer pH 9 was required to stabilize the AuNPs. The functional test of this conjugate was performed using dipstick LFIA, and the result shows that the AuNPs-mAb conjugates could successfully detect commercial spike antigen of SARS-CoV-2 at 10 ng level. Conclusion: In this study, laser-ablated AuNPs were functionalized with anti-spike mAb SARS-CoV-2 and successfully used as a signal reporter in half-stick LFIA for detecting antigen spike SARS-CoV-2.

The effect of isolated probiotics from Indonesian Passiflora edulis sims. on interferon gamma levels in peripheral blood mononuclear cell of adult tuberculosis patients in vitro.

Background: Mycobacterium tuberculosis (M.tb) is unique because the bacteria live intracellularly and hide in macrophages so that they can escape from phagocytosis. This is one of the factors that complicate the treatment of M.tb infections. Interferongamma (IFN-γ) is a compound that plays an important role in macrophage activation to control intracellular pathogens. Objective: The purpose of this research is to analyze the concentration of IFN-γ in peripheral blood mononuclear cells of adult Tuberculosis patients (TB) after in vitro administration of multistrain probiotics from indigeneous Indonesian red passion fruit (Passiflora edulis Sims.). Method: The probiotics isolated from red passion fruit were introduced into Peripheral Blood Mononuclear Cell (PBMC) adult TB patients who were undergoing Anti-tuberculosis Drug Therapy (ATD) category one at the Trosobo Primary Health Center (Sidoarjo, East Java, Indonesia), and the patients who were undergoing ATD category one treatment were willing to be involved in this study.Result: The probiotics isolated from fermentation-broth of Indonesian red passion fruit were able to increase IFN-γ levels in PBMC of adult TB patients. Conclusion: The red passion fruit probiotics isolated can increase IFN-γ of adult TB patients increased from 0.82% to 23.17% after in vitro administration.

Revealing the incorporation of an NH2 group into the edge of carbon dots for H2O2 sensing via the C-N⋯H hydrogen bond interaction.

We investigated hydrogen peroxide (H2O2) sensing on NH2-functionalized carbon dots (Cdots) for three different -NH2 positions, and the N atom was found to be the active site using a quantum computational approach. B3LYP and 6-31G(d,p) were used for density functional theory (DFT) ground state calculations, whereas CAM-B3LYP and the same basis set were used in time-dependent density functional theory (TD-DFT) excited state calculations. Structural optimization showed that the H2O2 is chemisorbed on 1-sim via a C-N⋯H hydrogen bond interaction with an adsorption energy of -10.61 kcal mol-1. Mulliken atomic charge distributions and electrostatic potential (ESP) analysis were both used to determine reactivity of the molecules at the atomic level. For in-depth analysis of the ground states, we utilized Frontier molecular orbital (FMO) theory, quantum theory of atoms in molecules (QTAIM), and non-covalent interaction (NCI) index analysis. In addition, we also present UV-vis absorption spectra and charge transfer lengths to understand the mechanism of H2O2 sensing in excited states. Based on the molecular and electronic properties of the NH2-Cdots, it was shown that 1-sim is a potential candidate for use as an electrochemical sensor for H2O2 sensing. Whereas 3-sim is believed to be a potential candidate for use as an optical sensor of H2O2 based on the UV-vis characteristics via photoinduced charge transfer.

Method Validation of Contact and Immersion TLC-bioautography for Determination of Streptomycin Sulfate in Shrimp.

OBJECTIVES: Contact and immersion thin layer chromatography (TLC)-bioautography were developed for identification and quantification of streptomycin sulfate in shrimp. MATERIALS AND METHODS: TLC of streptomycin sulfate standard solution was carried out using silica gel F254 and 7.5% of KH2PO4 solution as stationary and mobile phase, respectively. RESULTS: The retardation factor of the streptomycin sulfate standard was 0.51 and the selectivity of streptomycin sulfate was 4.1 with the presence of kanamycin sulfate in the shrimp. The bioautography was performed with Escherichia coli ATCC 8739 as a test bacterium. The limit of detection of streptomycin sulfate obtained by contact and immersion TLC-bioautography was 0.24 µg and 0.16 µg, respectively. Both methods showed good linearity with an r value greater than 0.999 and a Vxo value less than 2%. The accuracy of the contact and immersion TLC-bioautography was tested by standard addition method and the obtained percentage recovery was 86.93±1.60% and 96.42±0.65%, respectively. The coefficient of variation of the contact and immersion TLC-bioautography was 2.39±1.79% and 0.53±0.17%, respectively. CONCLUSION: The immersion TLC-bioautography was more sensitive with better recovery than the contact TLC-bioautography. In addition, immersion TLC-bioautography was successfully employed for determination of streptomycin sulfate in shrimp.

Inhibitory Effect of Roselle Aqueous Extracts-HPMC 6000 Gel on the Growth of Staphylococcus Aureus ATCC 25923.

OBJECTIVES: Roselle (Hibiscus sabdariffa L.) is a medicinal plant commonly used as a beverage and herbal medicine. Complex compounds in the aqueous extracts have provided good antibacterial activity by which the growth of gram-negative and -positive bacteria is inhibited. The aims of this research were to formulate hydroxypropyl methylcellulose (HPMC) 6000 gel containing the extract and investigate the inhibitory activity of the extract and its gel formula against Staphylococcus aureus ATCC 25923. MATERIALS AND METHODS: Thin layer chromatography (TLC) on silica gel GF254 was used for analyzing flavonoids and polyphenols using butanol: acetic acid: water (4:1:5) and chloroforms: ethyl acetate: formic acid (0.5:9:0.5) as eluent, respectively. A serial dilution of aqueous extract powder in citrate buffer was made to obtain 0.50, 0.25, 0.10, 0.05, and 0.02 mg/mL solution. The roselle aqueous extract (3%) was formulated as a component of gel containing HPMC 6000 in various concentrations (2%, 3%, and 4%). A diffusion agar method on two layers of nutrient agar media was applied using Staphylococcus aureus ATCC 25923 and gentamicin 25 ppm as bacterial test and standard, respectively. After incubation for 24 h at 37°C, the inhibitory effect was denoted by a clear zone around the hole and the inhibitory activity was measured as minimum inhibitory concentration (MIC). RESULTS: The aqueous extract of Hibiscus sabdariffa L. contained flavonoid and polyphenol compounds based on the TLC chromatogram profile. It was found that the gel formula containing 3% HPMC 6000 and 3% aqueous extract gave a good physical characteristic and the lowest MIC (6.0 mg/mL), equivalent to 7.58 ppm of gentamicin standard at 12.0 mg/mL concentration. CONCLUSION: The HPMC 6000 at 3% (w/w) concentration in roselle aqueous extract gel preparation gave good physical characteristics. The gel preparation exhibited inhibitory activity against Staphylococcus aureus ATCC 25923 shown by MIC 6.0 mg/mL. Formula 2 is recommended and should be further investigated for implementation in topical preparations.

Peel-off emulgel mask of Cocos nucifera L. Extract using gelling agent carbomer 940 as antiacne against Propionibacterium acnes ATCC 11827.

Cocos nucifera Linn., which contain lauric acid has been known had antibacterial activity against Propionibacterium acnes that usually improve severe of pimple. Current study investigated optimum formula of emulgel mask based on the C. nucifera L. Extract from Kopyor coconut. Extract were tested for antibacterial against P. acnes ATCC 11827. In this research, C. nucifera L. extract of 1 and 5% were formulated as an active agent of peel off antiacne emulgel mask-containing carbomer 940 in various concentration (1% and 1.5%). The peel-off emulgel mask of C. nucifera L extract was then evaluated in terms of viscosity, pH, drying time, spreadability, and antibacterial activity. The selected formula was formula containing 5% of extract and 1% of carbomer 940. This formula had pH that suitable with skin pH 4.5-6.5, had good spreadability, and also produced highest antibacterial activity against P. acnes.