DNA-Modulated Near-Infrared Photoluminescence Of Gallium Arsenide And Its Biosensing Application

With high electron mobility and the direct band gap structure, gallium arsenide (GaAs) has a strong photoluminescence (referred to as PL) signal in the near infrared region. So GaAs is appealing to optoelectronic devices. The inherent light emitting of GaAs is very sensitive to the physical and chemical state of its surface, which provides the possibility of its application in the developing the new-generation biosensors and bio-chips. Efficient near-infrared detection of specific DNA with single nucleotide polymorphism selectivity is important for diagnostics and biomedical research. Herein, we report the use of GaAs as a sensing platform for probing DNA immobilization and targeting DNA hybridization. The new signal amplification strategy, further coupled with the plasmonic effect of Au nanoparticles, is capable of detecting DNA molecules with very low detection and selectivity against single base mismatches.The main contents and results of this paper are as follows:First,by modification of DNA and under optimized conditions we explored the GaAs-based DNA detection by measuring near-infrared photoluminescence. The interaction between thiol modified DNA and GaAs was investigated via photoluminescence spectra and fluorescence microscopy. The 6-Mercapto-l-hexanol spacer not only adjusted DNA orientation and coverage density on GaAs surface but also prevented nonspecific adsorption of DNA from solution and displaced nonspecifically adsorbed DNA. Based on the measurement of near-infrared photoluminescence of gallium arsenide, a LOD of 0.2nM and a resolution of 294a.u./nM were obtained. (Chapter 2)Next, we used DNA molecular ruler to modulate the SP enhancement of GaAs photoluminescence. This experimentally approach was based on sequential steps of DNA functionalization, hybridization and self-assembly, which comprises two steps of thiol-chemistry reaction (Au-S, Ga-S or As-S) appended a relatively rigid dsDNA onto GaAs and GNPs, respectively. Moreover, we successfully employed GaAs surface as a sensing platform for the nIR photoluminescence detection of specific DNA sequences and identification of SNPs with an excellent detection limit of-0.8 pM. (Chapter 3)Finally, we constructed a sensing platform of biomarkers such as thrombin based on plasmonic enhancement of GaAs photoluminescence using gold nanoparticle, enabled high sensitive detection. The gold nanoparticle enhancement of GaAs photoluminescence was applied in this sensing platform, combined with specific binding of aptamers and proteins. High sensitive and selective detection of target thrombin was achieved, the limit of detection was as low as 80 pM. (Chapter 4)...