Applications of Gold Nanoparticles in Nanomedicine: Recent Advances in Vaccines †

Carabineiro, Sónia Alexandra Correia

Anionic gold nanoparticles increased the half-life of a green fluorescent protein expressing adenovirus from similar to 48 h to 21 days at 37 °C (from 7 to >30 days at room temperature) [61] . Promising CD8 + T cell results were obtained with polyelectrolyte multilayers assembled on gold nanoparticles [67, 68] . A positively charged antigen and a negatively charged immuno-adjuvant on gold nanoparticles resulted in a new vaccine platform. Usually nanoparticles are synthesized in colloidal solution by reduction of chloroauric acid (HAuCl 4 ) by variations of the so-called Turkevich method [46] . Their characterization is carried out by ultraviolet-visible spectroscopy, their diameters determined by transmission electron microscopy. Then, they can be further functionalized with the desired molecules, according to their specific needs. One example is given in Scheme 1, showing a procedure carried out by Saha et al. [47] . Gold nanoparticles were synthesized in aqueous medium by an ultra-sound assisted green method using black pepper extract and chitosan as reducing agent and a stabilizing agent, respectively. The biopolymer-inspired biogenic method (Scheme 1) was found to be stable and with enhanced bioactivity. The developed nanomaterial boosts the production of reactive oxygen species and misbalances the antioxidant parameters of detoxification enzymes of filarial parasites, such as GST, which besides its immune prophylactic potency, is also a promising candidate vaccine as shown in S. cervi and W. bancrofti [47] .