coli and P. aeruginosa. Table 1 shows antimicrobial activity results of various samples with their zone of inhibition. ROCK inhibitor positive control ciprofloxacin being a broad spectrum antibiotic showed distinct zone of inhibition against all bacteria with highest against gram negative P. aeruginosa

and relatively least against gram positive B. subtilis. Bare C-dots on the other hand, as compared to bare ciprofloxacin, showed less antimicrobial activity. The activity might be due to various functional groups present on C-dots which might react with cellular enzymes and inhibit cellular proliferation. In contrast to this, Cipro@C-dots conjugate showed enhanced antimicrobial activity against selective gram strain bacteria. Its activity Inhibitors,research,lifescience,medical was highest against gram negative P. aeruginosa and relatively less against gram positive B. subtilis but more than free C-dots or free ciprofloxacin. It could be inferred here that the antimicrobial activity is retained by the ciprofloxacin and C-dots which are acting in synergism

as a potent antimicrobial agent. Inhibitors,research,lifescience,medical It must be noted here that the complex also shows slight less activity against S. aureus and E. coli as compared to bare antibiotic. At the same time, bare C-dots did show potent antimicrobial activity towards these organisms. Hence, it can be hypothesized that may be the antibiotic from the final conjugate was released at a slower Inhibitors,research,lifescience,medical rate to act against these organisms. As shown earlier the antibiotic is released in a physiological pH. Hence, “selective

synergism” could be the right term to explain this scenario of the antimicrobial potential of Cipro@C-dots Inhibitors,research,lifescience,medical conjugate. Nevertheless, this property could be used in simultaneous imaging [32] and drug delivery. Table 1 Antimicrobial activity of bare C-dots, bare ciprofloxacin, and Cipro@C-dots conjugate on different gram positive and gram negative microorganisms. 4. Conclusions C-dots can act as efficient nanosink for delivery of therapeutic payloads such as ciprofloxacin Inhibitors,research,lifescience,medical due to their excellent biocompatibility, optical properties, and self-passivation properties. Ciprofloxacin can be easily anchored to self-functionalized C-dots without involvement of stringent protocols. Loading capacity of C-dots (>90%) shows it as an ideal vehicle for ferrying significant amount of clinical payloads. Also, path of C-dots can be traced due to its magnificent photoluminescence properties. The conjugate Electron transport chain was a potent antimicrobial in nature against both gram positive and gram negative bacteria. Potential antibiotics like ciprofloxacin can be released at sustained rate from the surface of C-dots, following Higuchi model under physiological conditions. Supplementary Material Supplementary material contains quantum yield values, elemental composition, drug loading -release calculations- results, cytotoxicity and fluorescence images. Click here for additional data file.(2.