Gold nanoparticles (AuNPs) are the groundwork of a large variety of applications in the biomedical field. Further development and a better understanding of this versatile platform will lead to an expansion of potential applications. In this study, we propose a facile synthesis of AuNPs using hydrogen peroxide as a reducing agent and collagen as a stabilizing agent. Our synthetic approach results in “raspberry”-like AuNPs with a mean diameter of 60 nm, as revealed by electron microscopy. The optical properties of the AuNPs were assessed by UV-Vis and surface-enhanced Raman scattering (SERS), and their stability and in vitro cytotoxicity were evaluated as well. HeLa cell viability values were only modestly affected compared to control, with the highest concentration tested displaying a 20% decrease in cellular viability. The dose-dependent cellular internalization in the 20–60 nM range indicate the highest internalization rate at 60 nM and uptake values as high as 35%. This result correlated well with the viability results. These type of anisotropic AuNPs are proposed for biomedical applications such as hyperthermia, contrast agents or imaging. Therefore, our findings offer a platform for potential biological applications such as sensing and imaging, due to their unique physico-chemical features.

Raman mapping is becoming a very useful tool in investigating cells and cellular components, as well as bioactive molecules intracellularly. In this study, we have encapsulated beta-carotene using a layer-by-layer technique, as a way to enhance its stability and bioavailability. Further, we have used Raman mapping to characterize the as-obtained capsules and monitor their uptake by the human retinal epithelial D407 cells. We were able to successfully map the beta-carotene distribution inside the capsules, to localize the capsules intracellularly, and distinguish between capsules and other cellular components.