Tailored coating of gold nanostars: rational approach to prototype of theranostic device based on SERS and photothermal effects at ultralow irradiance

Abstract

The last decade has come across an increasing demand for theranostic biocompatible nanodevices possessing the double ability of diagnosis and therapy. In this work, we report the design, synthesis and step-by-step characterization of rationally coated gold nanostars (GNSs) for the SERS imaging and photothermal therapy of HeLa cancer cells. The nanodevices were realized by synthesizing GNSs with a seed growth approach, coating them with a controlled mixture of thiols composed of a Raman reporter and a polyethylene glycol with a terminal amino group, and then reacting these amino groups with folic acid (FA), in order to impart selectivity towards cancer cells which overexpress folate receptors on their membranes. After a complete characterization, we demonstrate that these FA-functionalized GNSs (FA-GNSs) are able to bind selectively to the membranes of HeLa cells, acting as SERS tags and allowing SERS imaging. Moreover, we demonstrate that once bound to HeLa cell membranes, FA-GNSs exhibit photothermal effect which can be exploited to kill the same cells in vitro using laser irradiation in the NIR at a very low and safe irradiance. We thus demonstrate that the FA-GNSs designed following the described approach are an efficient prototype of theranostic nanodevices.

Engineered Gold-Based Nanomaterials: Morphologies and Functionalities in Biomedical Applications. A Mini Review

“…This review shows the advantages and disadvantages of the different morphologies, considering the dimension, functionalization and bioapplication. In this regard, in the wide biomedicine field, four main areas of applications are typically identified: therapy, diagnostics, drug/gene delivery, and sensors, as schematically shown in Figure 2 [4,8,10,12,16,17,18,21,28,29,30,31,32,33,34,37,38,39,48,51,53,70,71,72,75,76,77,78,79,80,81,82,83,84,85,90,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,…”

“…The concept of theranostic AuNP nanocomposites emerged for gold-based nanomaterials and combines the functionalities of both contrast and therapeutic agents within a single object. AuNPs, AuNRs, AuNSs and AuNcages were used as theranostic agents because they combine imaging and therapeutic roles [30,76,100,129].…”

“…In the last decade, nanotechnology allowed for an improvement of materials properties in many application fields, such as sensing [1,2,3,4,5,6,7,8,9], optoelectronics [10,11,12,13,14,15], energy [16,17,18,19,20,21], catalysis [22,23,24] and biotechnology [25,26,27,28,29,30,31]. Gold was used to produce many different nanostructures through a bottom-up approach, such as spheres, rods, stars, cubes, hollow nanoparticles, and nanocapsules, widely used in biomedicine and reported in a schematic way in Figure 1.…”

“…Gold was used to produce many different nanostructures through a bottom-up approach, such as spheres, rods, stars, cubes, hollow nanoparticles, and nanocapsules, widely used in biomedicine and reported in a schematic way in Figure 1. These nanostructures showed remarkable chemical-physical properties, and often their superficial functionalizations allow a response to environmental changes, such as variations in the temperature, pH, light, and redox potentials [6,8,26,30,32,33,34,35]. This represented an amazing opportunity for their use in active therapies, as drug carriers, as theranostic agents, and as sensing materials [6,26,30,33,36,37,38,39].…”

“…Therefore, they show optical labeling functions like organic ones. These kinds of probes have a typical ultrasensitivity, as well as the multiplexing and quantitative skills of the SERS technique, and they show amazing potentials for bioanalysis [6,26,30].…”