Vijayan, VMShenoy, SJVictor, SPMuthu, J2016-08-012016-08-012016-06Vijayan V M, Shenoy S J, Victor S P, Muthu J. Stimulus responsive nanogel with innate near IR fluorescent capability for drug delivery and bioimaging. Colloids and Surfaces B: Biointerfaces. 2016;146(1):84-96anhydridehttp:// dx.doi.org/10.1016/j.colsurfb.2016.05.059https://dspace.sctimst.ac.in/handle/123456789/2792A brighter, non toxic and biocompatible optical imaging agent is one of the major quests of biomedical research. Here in, we report a photoluminescent comacromer [PEG-poly(propylene fumarate)-citric acid-glycine] and novel stimulus (pH) responsive nanogel endowed with excitation wavelength dependent fluorescence (EDF) for combined drug delivery and bioimaging applications. The comacromer when excited at different wavelengths in visible region from 400 nm to 640 nm exhibits fluorescent emissions from 510 nm to 718 nm in aqueous condition. It has high Stokes shift (120 nm), fluorescent lifetime (7 nanoseconds) and quantum yield (50%). The nanogel, C-PLM-NG, prepared with this photoluminescent comacromer and N,N-dimethyl amino ethylmethacrylate (DMEMA) has spherical morphology with particle size around 100 nm and 180 nm at pH 7.4 (physiological) and 5.5 (intracellular acidic condition of cancer cells) respectively. The studies on fluorescence characteristics of C-PLM NG in aqueous condition reveal large red-shift with emissions from 523 nm to 700 nm for excitations from 460 nm to 600 nm ascertaining the EDF characteristics. Imaging the near IR emission with excitation at 535 nm was accomplished using cut-off filters. The nanogel undergoes pH responsive swelling and releases around 50% doxorubicin (DOX) at pH 5.5 in comparison with 15% observed at pH 7.4. The studies on in vitro cytotoxicity with MTT assay and hemolysis revealed that the present nanogel is non-toxic. The DOX-loaded C-PLM-NG encapsulated in Hela cells induces lysis of cancer cells. The inherent EDF characteristics associated with C-PLM NG enable cellular imaging of Hela cells. The studies on biodistribution and clearance mechanism of C-PLM-NG from the body of mice reveal bioimaging capability and safety of the present nanogel. This is the first report on a polymeric nanogel with innate near IR emissions for bioimaging applications.Excitation dependent fluorescence Near IR Nanogel BioimagingArticle