Gold nanoparticles - Aunps

Gold nanoparticles (AuNPs) Gold nanoparticles are spherical particles with diemeter 1-100nm. They present excellent optical properties which make them ideal candidates for the development of novel diagnostics techniques. Gold nanoparticles in colloidal form show an intense red colour which turns purple every time aggregates are formed. This feature combined with the ability of gold nanoparticles to bound to various organic molecules such as DNA, RNA and proteins allows us to investigate their potential use in the detection of pathogens in food. Materials required for AuNPs-probe conjugation: Accurate Spherical Gold Nanoparticles 20 nm, PBS, SDS, Salting buffer 2 M, Thiolated probes In a glass vial add 1 ml Gold Nanoparticles and 40 _l thiolated probe (100pmol/_l) and place it on an orbital shaker overnight at room temperature. Add PBS and SDS to obtain a final concentration of 9 mM and 0.1% (wt/vol) respectively and place it on an orbital shaker for 30 min Over the course of 24 hours, make 5 additions of one-fifth of the total salting buffer needed to reach a final concentration of 0.3 M NaCl [After 25 Hours] Spin all the solution at 13,000xg for 15 min. Remove the supernatant and resuspend in 500 _l reaction buffer. Repeat 7 times After the last spin, resuspend the AuNPs-probe in 500 _l reaction buffer and store at RT DNA detection Materials required: AuNPs-probe conjugate, reaction buffer, HCl 0.1N In a vial add 50 _l reaction buffer,10 _l DNA and incubate at 95°C for 5 min for the denaturation Add 10 _l of each AuNPs-probe conjugate and incubate at RT for 5 min Add 10 _l of HCl 0.1 N, incubate 10-20 min and detect any color change visually The results were confirmed by measurement in photometer, where at negative samples the peak of the absorbance curve moves towards purple