Sustainable chemistry approach for the preparation of bluish green emissive copper nanoclusters from Justicia adhatoda leaves extract: a facile analytical approach for the sensing of myoglobin and l-thyroxine

Abstract

Justicia adhatoda is commonly known as Malabar nut or adulsi and extensively used for various medicinal applications such as bleeding disorders, piles, and hemorrhage, particularly musculoskeletal and cardiac diseases. Development of medicinal plant extract-derived metal nanoclusters for the detection of biomolecules has received great attention in recent years. In this paper, bluish-green fluorescent copper nanoclusters (Cu NCs) are synthesized with a quantum yield of 17.12% via green chemistry using Justicia adhatoda plant extract as a template. The morphology, size, surface chemistry and elemental oxidation states of the J. adhatoda–Cu NCs are confirmed by high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopic techniques. In the presence of myoglobin, the emission peak of J. adhatoda–Cu NCs at 478 nm was drastically quenched and similarly the emission peak was greatly enhanced with the addition of L-thyroxine. Moreover, the J. adhatoda–Cu NC-based fluorescent probe exhibited high sensitivity for myoglobin and L-thyroxine with detection limits of 1.92 and 7.4 nM, respectively. Moreover, the J. adhatoda–Cu NCs acted as probes for the imaging of Saccharomyces cerevisiae cells. This method was successfully applied to quantify myoglobin in biofluids and L-thyroxine in pharmaceutical samples.