**4. Characterisation of nanoparticles**

produced pink-coloured aggregates. The aggregates were isolated under centrifuged condi‐ tions (4500 rpm for 20 min) followed by overnight drying at 60 ◦C to afford 0.5 mg of the final nanomaterials. All the PABA based nanomaterials C11, C11U, C12, C14. C16, c18 and C18U

**Figure 2.** Design and chemical synthesis of nanomaterials. (A) chemical structure of acid side chains, final self assem‐ bled product reaction condition, percentage of yield, fluorescent dyes summarized in a table. (B) Schematic diagram showing formation of two nanoparticles (C12 and C18) was drawn (C) Routine diagram and compatible SEM images

Prior to the study of the cellular uptake of the seven nanomaterials which use the PABA template, a study was also undertaken to observe whether the biological properties of PABA changed due to the side chain substitution and self-assembly. The biological properties of PABA in self-assembled conjugates as monitored by the growth and viability of the wild type bacterial strains (E. coli K12) in cultured media in the presence of PABA or PABA containing nanostructures. A similar level of bacterial growth in culture media containing PABA or PABA

showing rollover mechanism of two nanomaterial (C-14 and C16) formation.

studied obtained by side chain variation are shown in Figure 2.

450 Application of Nanotechnology in Drug Delivery

Laser confocal microscopic images showed that three nanostructures, C-11, C-16 and C-18 emitted intrinsic green fluorescence, while remaining four nanomaterials (C-11U, C-12, C-14, C-18U) do not emit any intrinsic fluorescence (Figure 3). To verify the fluorescence enhance‐ ment, induced by self-assembly nanostructure, the fluorescence emission of the monomer and the self-assembled nanoparticles were compared using Nanodrop 3300 fluoro-spectrometer. The fluorescence intensity of the nanostructures (determined by a methanol/water solution) using blue diode option (maximum excitation 477 nm) was much stronger and found in 510 nm than that of the non-fluorescent monomer (studied in CH2Cl2, where it does not aggregate) under the same 0.3 wt % concentration.
