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The demand for next-generation multifunctional nanovectors, combining therapeutic effects with specific cellular targeting, has significantly grown during the last few years, pursuing less invasive therapy strategies. Polyphenol-conjugated silver nanoparticles (AgNPs) appear as potential multifunctional nanovectors, integrating the biorecognition capability and the antioxidant power of polyphenols, the antimicrobial activity of silver, and the drug delivery capability of NPs. We present a spectroscopic and microscopic investigation on polyphenol-synthesized AgNPs, selecting caffeic acid (CA) and catechol (CT) as model polyphenols and using them as reducing agents for the AgNP green synthesis, both in the presence and in the absence of a capping agent. We exploit the plasmonic properties of AgNPs to collect Surface-Enhanced Raman Scattering (SERS) spectra from the nanosized region next to the Ag surface and to characterize the molecular environment in the proximity of the NP, assessing the orientation and tunable deprotonation level of CA, depending on the synthesis conditions. Our results suggest that the SERS investigation of such nanovectors can provide crucial information for their perspective biomedical application. [ABSTRACT FROM AUTHOR]

Multi-responsive nanomaterials based on the self-limited assembly of plasmonic nanoparticles are of great interest due to their widespread employment in sensing applications. We present a thorough investigation of a hybrid nanomaterial based on the protein-mediated aggregation of gold nanoparticles at varying protein concentration, pH and temperature. By combining Small Angle X-ray Scattering with extinction spectroscopy, we are able to frame the morphological features of the formed fractal aggregates in a theoretical model based on patchy interactions. Based on this, we established the main factors that determine the assembly process and their strong correlation with the optical properties of the assemblies. Moreover, the calibration curves that we obtained for each parameter investigated based on the extinction spectra point out to the notable flexibility of this nanomaterial, enabling the selection of different working ranges with high sensitivity. Our study opens for the rational tuning of the morphology and the optical properties of plasmonic assemblies to design colorimetric sensors with improved performances. [ABSTRACT FROM AUTHOR]

Coherent random lasers (RLs) originate from the resonant amplification of the light scattered by disordered media resulting in spiky emission spectra with well‐defined spectral signatures. Here coherent RL emission is proposed as a tool for identifying the spectral fingerprint of porous micro‐structured materials obtained by soft lithography techniques. The close control of the spatial patterns and structural characteristics of the scattering elements enable us to obtain stable and unique RL spectra distinctive of each lithographed device. The spectral emission has been thoroughly analyzed with respect to the morphology of the devices in terms of surface roughness and surface volume fraction, demonstrating that the packing of the scattering particles is the main factor in determining a RL emission characterized by multiple linewidths with a high level of coherence. The findings provide novel insights for the realization of miniaturized photonic devices with selectable optical features. [ABSTRACT FROM AUTHOR]