This solution was used to fabricate [email protected] conjugate because of its high stability, small size, and typical PL properties as discussed above. UV-Vis spectrum
of ciprofloxacin (Figure 4(a)) shows two distinct peaks at 272 and 330nm, which arise due to π → π* transitions of the fluorobenzene moieties and quinolone ring, respectively . In Inhibitors,research,lifescience,medical comparison to dialyzed C-dots (peaks at 218 and 264nm) and ciprofloxacin, a new peak at 269nm can be seen which is due to [email protected] conjugate. Intensity of the peak was found to be deceased after dialysis of the conjugate against nanopure water in order to remove unattached ciprofloxacin (Figure 4(a)). PL intensity of C-dots was also found to be diminished after attachment of ciprofloxacin and a red shift from 442nm to 540nm was observed Inhibitors,research,lifescience,medical as displayed in Figure 4(b). There can be the following reason for this phenomenon: involvement of essential functional groups in formation of chemical interactions which are otherwise responsible for fluorescence of C-dots and/or ciprofloxacin
induced cross linking of C-dots could also lead to quenching of PL properties. Inhibitors,research,lifescience,medical Figure 4 (a) UV-Vis spectra of (i) ciprofloxacin (inset showing its chemical structure), (ii) C-dots, (iii) [email protected] conjugate, and (iv) postdialysis sample of [email protected] conjugate and (b) PL spectra of respective samples (ii–iv) with λex … A comparative Inhibitors,research,lifescience,medical Fourier transformed infrared (FTIR) spectrum depicting the interaction between C-dots and ciprofloxacin is displayed in Figure 5. Self-passivized C-dots (Figure 5(a)) show typical peaks at 1024, 1446, and 1598cm−1 which can be assigned to C–N stretching, −CH bending, and C=C selleck stretch of aromatic rings, respectively. Other signals correspond to −C-H stretching (both 2848 and 2916cm−1) Inhibitors,research,lifescience,medical and alcoholic −OH stretch from aqueous solution
and −NH stretch of primary amines (3485 and 3769cm−1) (Figure 5(a)). These are essential functional groups associated with surfaces of C-dots as per previous studies . Figure 5(b) shows bare ciprofloxacin, which, on the other hand, LANCET displays typical peaks at 880, 1050, 1451, and 1630cm−1 which arise due to −CH bends of aromatic rings, C–N stretching, −OH bend of carboxylic acid, and C=C stretching, respectively, which are typical molecular signatures of ciprofloxacin . Bands at 1736, 2981, and 3390cm−1 are due to −C=O stretching of carboxylic acids, −CH stretch of alkanes, and −NH stretching of 1° amines, respectively.