[21]. The use of GaAs as nIR optical sensors is of particular interest in clinical or medical settings because PL occurs in a region of the electromagnetic spectrum in which blood and tissue are particularly transparent 0110 and 0115. Currently, the nanostructured gold on GaAs has been synthesized, and the investigation of the PL properties of GaAs suggested that the gold nanostructures can influence the emission properties of the semiconductor 0085, 0120 and 0125. More recently, [23]. we reported that DNA could have the selective modulation of GaAs PL with combination of DNA hybridization activity. And we also demonstrated that DNA-decorated gold nanoparticles (GNPs) could enhance PL emission of GaAs, resulting in an ultrasensitive DNA detection. Despite these progresses, the tunable controlling GNPs-induced plasmonic enhancement with DNA molecules remains to be further explored and understood. Moreover, to the best of our knowledge, there is little effort to expend on using the DNA to develop nanoplasmonic molecular ruler on nIR photoluminescent semiconducting platform.
In this article, we report the use of DNA molecular ruler to modulate the PL emission of GaAs with SP enhancement. A well-defined GNPs/GaAs hybrid surface with DNA junction has been designed and demonstrated, as schematically represented in Fig. 1. This experimental approach was based on sequential steps of DNA functionalization, DNA hybridization and GNPs self-assembly on GaAs, 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 [23]. This simple method offers a facile nonlithograhic strategy to modify large flat GaAs substrates with GNPs. Next, we found that the DNA-mediated self-assembly of GNPs onto GaAs could enhance the PL emission from GaAs. It is proposed that the DNA-length dependent PL enhancement is resulted from the known as the mechanism of metal-enhanced fluorescence.