The development of fluorescent silica nanoparticles (SNP-RB) from natural amorphous silica and its performance as an Escherichia coli (E. coli) biosensor is described in this paper. SNP-RB was derived from silica recovered from geothermal installation precipitation and modified with the dye, Rhodamine B. The Fourier Infrared (FTIR) confirms the incorporation of Rhodamine B in the silica matrix. Transmission Electron Microscopy (TEM) micrographs show that the SNP-RB had an irregular structure with a particle diameter of about 20–30 nm. The maximum fluorescence spectrum of SNP-RB was recorded at 580 nm, which was further applied to observe the detection performance of the fluorescent nanoparticles towards E. coli. The sensing principle was based on the fluorescence-quenching mechanism of SNP-RB and this provided a wide linear E. coli concentration range of 10–105 CFU/mL with a limit detection of 8 CFU/mL. A rapid response time was observed after only 15 min of incubation of SNP-RB with E. coli. The selectivity of the biosensor was demonstrated and showed that the SNP-RB only gave quenching response only to live E. coli bacteria. The use of SNP-RB as a sensing platform reduced the response time significantly compared to conventional 3-day bacterial assays, as well having excellent analytical performance in terms of sensitivity and selectivity.

Dengue virus distributed in tropical and subtropical regions in the world. DENV viruses are transmitted between humans primarily by Aedes aegypti and Aedes albopictus mosquitoes and are endemic in most areas in which the vectors occur. Four serotypes of dengue virus are DENV-1, DENV-2, DENV-3 and DENV-4. DENV-2 is comprised of six genotypes. Ethanol precipitation is a commonly used technique for concentrating and de-salting nucleic acids (DNA or RNA) preparations in aqueous solution. RNA isolation by combining Guanidinium thiocyanate and phenol reported has been reported. In this report, we investigated RNA isolation from DENV-2 using QIAamp Mini Kit with 2-Isopropanol, Methanol, Chloroform precipitation solvent. Electrophoregram showed DNA band as  the result of RNA isolation with methanol and 2-isopropanol are produced quite well. Dna band of the of RNA isolation with chloroform solvent has the lowest intensity than methanol and 2-isopropanol. This study showed that methanol and 2-isopropanol  can used as precipitation solvent for isolating RNA.

Dengue virus (DENV) serotypes possess various types from DENV-1 to DENV-4 that are enveloped viruses belong to the genus Flavivirus of the Flaviviridae. Dengue vaccine or antiviral has not yet been clinically approved for humans, even though there have been significant efforts toward this end. Antiviral activity against DENV is needed to develop to be an alternative drug for the DENV virus. Cobalt(II) chloride has been used in the treatment and prevention of diseases of humans since ancient times. This study aimed to investigate the antiviral effects and Cytotoxicity of Cobalt(II) chloride. This compound was further investigated for its inhibitory effect on the replication of DENV-1 in Vero cells. The antiviral activity and cytotoxic was measured by WST-1 assay. The IC50 value of the Cobalt(II) chloride for DENV-1 was 0.38 μg/ml. The cytotoxicity of Cobalt(II) chloride to Vero cell suggests that the CC50 value was 2.91 µg/ml. The results of this study demonstrate the anti-dengue serotype 1 inhibitory activity of Cobalt(II) chloride was highly toxic.

Rhodamine B can be used as a fluorophore to produce fluorescent silica nanoparticles derived from geothermal sludge. The purpose of this research is to synthesize fluorescent silica nanoparticles (FSNP) modified with rhodamine B and cetyl trimethyl ammonium bromide (CTAB) using sol-gel method. Geothermal waste was used as a precursor and added with NaOH at 900C to generate sodium silicate. Rhodamine B, as the fluorescent dye were added with concentration variations ranging from 0.156 mg/g to 10 mg/g.CTAB was used as template and HCl 2N was applied as gelling catalyst with aging time of 18 hours. Characterization of FSNP was measured using spectrofluorometer to identify the fluorescent intensity, fourier transform infrared (FT-IR) to determine the functional group of FSNP, Brauner-Emmett-Teller (BET) adsorption to calculate the specific area of the particles, X-ray diffraction (XRD) to analyze the crystallographic phases, and transmission electron microscopy (TEM) to analyze the surface morphology of the FSNP. FT-IR and fluorescent intensity results showed that FSNP with 2.5 mg/g of rhodamine B had the optimum characteristics. The FSNP was in amorphous phase with uniform pore distribution. BET analysis showed that the specific surface of the FSNP was 190.22 m2/g.