Alkahtani, Masfer Hassan A (2018-04). Engineering Fluorescent Nanodiamonds and Upconversion Nanoparticles for Bioimaging and Optical Temperature Sensing. Doctoral Dissertation.
Thesis
An ideal fluorescent marker for high contrast imaging and optical temperature sensing in biological applications should be biocompatible, ultrasmall, photostable, and can be excited and detected within the biological transparency window (650-1350nm). To meet these criteria, fluorescent nanodiamonds (FNDs) and upconversion nanoparticles (UCNPs) doped with lanthanide ions Ln+3 (Ln=Er,Tm,Ho,etc.) are of interest. First, multi-color fluorescent nanodiamonds (FNDs) containing variety of color centers are promising fluorescent markers for most of biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity and better photostability. FNDs can be as small as fluorescent proteins, for example, green fluorescent protein (GFP) with a few nanometers (nm) in size and have exceptional chemical stability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this dissertation, I will discuss a new technique of grown small and stable fluorescent nanodiamonds. I will also discuss some applications of FNDs in bioimaging and biosensing. Second, Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, Y V O4 : Er+3, Yb+3 nanoparticles were shown to exhibit strong up-conversion luminescence (UCL) with a relatively low 10 kW.cm?2 excitation intensity even in water, which makes them excellent bio-imaging and biosensors candidates. In this dissertation, I will discuss the UCNPs in terms of synthesis, applications in bioimaging and biosensing.
