Fabrication of Luminescent CdS Nanoparticles on Short-Peptide-Based Hydrogel Nanofibers: Tuning of Optoelectronic Properties

The pH-induced self-assembly of three synthetic tripeptides in water medium is used to immobilize luminescent US nanoparticles. These peptides form a nanofibrillar network structure upon gelation in aqueous medium at basic pH values (pH 11.0-13.0), and the fabrication of US nanoparticles on the gel nanofiber confers the luminescent property to these gels. Atomic force microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy clearly reveal the presence of US nanoparticles in a well-defined array on the gel nanofibers. This is a convenient way to make organic nanofiber-inorganic nanoparticle hybrid nanocomposite systems. The size of the US nanoparticles remains almost same before and after deposition on the gel nanofiber. Photoluminescence (PL) measurement of the US nanoparticles upon deposition on the gel nanofibers shows a significant blue shift in the emission spectrum of the nanoparticles, and there is a considerable change in the PL gap energy of the US nanoparticles after immobilization on different gel nanofibrils. This finding suggests that the optoelectronic properties of US nanoparticles can be tuned upon deposition on gel nanofibers without changing the size of the nanoparticles.