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Early diagnosis is one of the most important factors in determining the prognosis in cancer. Sensitive detection and quantification of tumour-specific biomarkers have the potential to improve significantly our diagnostic capability. Here, we introduce a triggerable aptamer-based nanostructure based on an oligonucleotide/gold nanoparticle architecture that selectively disassembles in the presence of the biomarker of interest; its optimization is based also on in-silico determination of the aptamer nucleotides interactions with the protein of interest. We demonstrate this scheme for the case of Prostate Specific Membrane Antigen (PSMA) and PSMA derived from PSMA-positive exosomes. We tested the disassembly of the system by diameter and count rate measurements in dynamic light scattering, and by inspection of its plasmon resonance shift, upon addition of PSMA, finding appreciable differences down to the sub-picomolar range; this points towards the possibility that this approach may lead to sensors competitive with diagnostic biochemical assays that require enzymatic amplification. More generally, this scheme has the potential to be applied to a broad range of pathologies with specific identified biomarkers., (© 2023. The Author(s).)

Developing safe and high efficiency contrast tools is an urgent need to allow in vivo applications of photoacoustics (PA), an emerging biomolecular imaging methodology, with poor invasiveness, deep penetration, high spatial resolution and excellent endogenous contrast. Eumelanins hold huge promise as biocompatible, endogenous photoacoustic contrast agents. However, their huge potential is still unexplored due to the difficulty to achieve at the same time poor aggregation in physiologic environment and high PA contrast. This study addresses both issues through the design of a biocompatible photoacoustic nanoprobe, named MelaSil_Ag-NPs, relying on silica-templated eumelanin formation as well as eumelanins redox and metal chelating properties to reduce Ag + ions and control the growth of generated metal nanoparticles. This strategy allowed self-structuring of the system into a core-shell architecture, where the Ag core was found to boost PA signal, despite the poor eumelanin content. Obtained hybrid nanoplatforms, showed stable photoacoustic properties even under long irradiation. Furthermore, conjugation with rhodamine isothiocyanate allowed particles detection through fluorescent imaging proving their multifunctional potentialities. In addition, they were stable towards aggregation and efficiently endocytosed by human pancreatic cancer cells (BxPC3 and Panc-1) displaying no significant cytotoxicity. Such numerous features prove huge potential of those nanoparticles as a multifunctional platform for biomedical applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Yellow-green controlled photorelease: probes click-linked to peptide-coated gold nanospheres by a triazole ring can be released in living cells under a focused 561 nm laser at low power. Photocleaving follows a three-photon event stimulated by the excitation of the localized surface plasmon resonance., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A single-step method to coat and bifunctionalize water-reduced gold nanoparticles (NPs) with two distinct reactive groups is reported. The coating is based on a peptide that bonds to the NPs surface by its N-cysteine amino acid, terminates with a C-terminal lysine, and stabilizes the colloids, thanks to the surface organization provided by the rest of the non-polar chain. The process yields stable, non-cytotoxic NPs presenting reactive amine and carboxylic groups on the surface; these allow rapid, selective and modular conjugation of virtually any chosen biomolecule or fluorophore. Functionalized and conjugated nanostructures are analyzed by electrophoresis, SEM, SERS; their biocompatibility and delivery capability are tested by cellular-uptake experiments.