Silver nanostructures have been always a material of attraction due to its outstanding electrical and optical features. Here, silver nanorods (AgNRs) array fabricated on glass substrates by electron beam dynamic angle deposition, has been employed in biosensing applications. The average length and diameter of the nanorods were determined to be 900 nm and 100 nm respectively by electron microscopy. The colorimetric and water wetting properties of as-fabricated AgNRs arrays were found to be highly sensitive towards the sulfurization. In the presence of H2S gas, the as-fabricated whitish AgNRs array turns black (due to formation of black Ag2S). In addition, it also changes its water wetting property from hydrophobic (water contact angle CA=128°) to hydrophilic (CA=65°). The coproduct of the reaction; OH- ions on the AgNRs surface may found to attribute to enhance the wettability. The dual mode rapid and selective detection of H2S gas was demonstrated by using a house-made android based mobile app “Colorimetric Detector”. The performance of the sensor was investigated by its sensing ability of 5 ppm of gas with exposure time of only 30 seconds. This novel method of detection also employed to detect the H2S gas from bacterial cells in order to determine their viability and antibiotic resistance. The method was found user-friendly, cost effective and time saving as compare to conventional techniques. The used substrates (sulfurized silver) in abovementioned applications were confirmed as the Ag-Ag2S, which were further utilized in various potential applications e.g. photocatalytic dye degradation under visible light irradiation, photoelectrochemical reaction in the study of hydrogen production, SERS based chemical detection and antimicrobial activity. In the view of highly efficient plasmonic property of uniformly arranged noble metal nanoparticles, AgNRs array were found to the potential SERS substrates with Raman signal enhancement factor of 108. A portable early stage Dengue diagnostic platform was developed and successfully distinguished the clinical blood samples as Dengue positive, negative and healthy individuals with the help of a statistical data analyzing tool (Principal Component Analyzer; PCA).