Research Projects

Nowadays bioimaging became one of the best tools to obtain, practice, and picturise functional images of living cells at preferred spatial and temporal measures. Recently phosphor materials acquired a vital role in drug delivery, and vivo cell imaging [1-5]. The organic fluorophores were highly focused on biomedical usage. However, these fluorophores are not suitable for long-time detection since they are susceptive to photobleaching and emission Stokes shift. Quantum dots (QDs) are featured with good photostability. But the toxicity of heavy metallic constitutes of QDs raises general biosafety concerns. Upconverted nanoparticles (UCN) are used for bioimaging since UNC can be excited by NIR photons which have excellent tissue penetration depth. However, the widely used NaYF4: Er3+, Yb3+ UCN for biomedical applications is not chemically stable and needs continuous pumping by NIR light which can cause cell damage due to the generated heat by NIR photons. Also, the synthesis process of this composition is difficult [6-8]. Hence the urge for low-cost synthesis of efficient deep red as well as NIR-emitting persistent phosphors has grown up owing to their application in bioimaging particularly for in vitro applications [9, 10]. Deep red to NIR range emission of these phosphors corresponds to the higher transmittance wavelength range of biological tissue (called biological optical window). Most importantly, persistent emission is having many advantages over upconverting phosphors. These phosphors can emit light even after the removal of the source of excitation. The cell damage due to continuous irradiation can be avoided by using post irradiated persistent phosphors, which can able to emit photons for a period of time even after removing the irradiation source. Hence, bioimaging using this phosphor is usually non-destructive in nature [3, 11]. The Mn4+ or Cr3+-activated gallogermanates are the best candidates for producing light in the deep-red to NIR region. These compounds are having no toxicity, good stability and efficiency, lower cost, and eco-friendly preparation method. It is important to be mentioned that Cr3+ is not toxic and essential need for life in traces. Hence this proposal is aiming for the development of new Mn4+/Cr3+ doped gallogermanates with long persistent deep red to NIR emission for in vitro applications [12, 13]. Here Ga3+ is capable of providing suitable sites for Cr3+ and Ge4+ can provide suitable sites for Mn4+ to produce NIR and deep red light, respectively. Since nanocrystals are highly required for in vitro applications, an efficient route will be used for the production of these nanomaterials with desired morphology. To reach high emission intensity and long persistent time from these compositions, appropriate cationic and sensitizer inclusion methodologies will be adopted. The optimized compositions with suitable size, morphology, and persistent emission will be used for in vitro applications.