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Fluorescent carbon nanodots are a promising nanomaterial for different applications in biophotonics, sensing and optical nanothermometry fields due to their strong fluorescence properties. However, their multi-modal applications are considerably limited, requiring the use of several nanoagents that could solve different tasks simultaneously. In this paper, we report the first experimental results on a facile "green" laser-based synthesis of multi-modal carbon–metallic nanocomposites with tuned optical performance. This simple approach leads to the appearance of finely controlled plasmonic properties in carbon-based nanocomposites whose spectral position is adapted by using an appropriate material. Thus, longer laser ablation provokes 29-fold increase in the absorption intensity of carbon–gold nanocomposites due to the increase in the metal content from 13% (30 s) to 53% (600 s). Despite strong plasmonic properties, the metal presence results in the quenching of the carbon nanostructures' fluorescence (2.4-fold for C-Au NCs and 3.6-fold for C-Ag NCs for 600 s ablation time). Plasmonic nanocomposites with variable metal content reveal a ~3-fold increase in the laser-to-heat conversion efficiency of carbon nanodots matching the temperature range for mild hyperthermia applications. The findings presented demonstrate a facile approach to expanding the properties of chemically prepared semiconductor nanostructures due to the formation of novel semiconductor–metallic nanocomposites using a "green" approach. Together with the ease in control of their performance, it can considerably increase the impact of semiconductor nanomaterials in various photonic, plasmonic and biomedical applications. [ABSTRACT FROM AUTHOR]

The design of semiconductor-metallic nanostructures using pulsed laser ablation in liquids (PLAL) is a very demanding task for biomedical applications being at an early stage of its development. Only few recent papers show the possibility of such a synthesis of composite nanoparticles as well as their perspectives for biosensing applications. However, mechanisms of the laser-stimulated formation of semiconductor-metallic nanoparticles involving several processes are not clarified yet being considerably depended on experimental conditions. In this work, we demonstrated an impact of the laser irradiation of colloidal solutions of silicon nanoparticles at different exposure time in the presence/absence of a gold target. In particular, longer ablation of the metal led to a stronger plasmonic maximum in silicon nanoparticles at around 520 nm. It also decreased the hydrodynamic size from 165 nm to 85 nm as well as the ξ-potential from -46 mV to -30 mV by increasing the ablation time from 0 s to 600 s. At the same time, the lowest electrical conductivity value (~1.5 µS/cm) of the plasmonic nanocomposites was detected at 120 s irradiation time. The highest concentration of synthesized composite nanoparticles (~3·1011 NPs/mL) was achieved at 180 s ablation time. Another purpose of the paper was to reveal an influence of the used laser irradiation on properties of the colloidal solutions of silicon nanoparticles themselves. It was found a considerable decrease of their absorbance with the increase of the laser exposure time that can be associated with the change of their properties (e.g. concentration, size, oxidation state etc.). Thus, the laser irradiation strongly affects properties of colloidal solutions of silicon nanoparticles that must also be taken into account considering possible mechanisms of the formation of composite nanostructures. Presented in the paper fast optical diagnostic can help to determine properties of colloidal solutions of nanocomposites formed by PLAL prior their biomedical or catalytic applications. [ABSTRACT FROM AUTHOR]

Silicon nanostructures can be prepared by different methods that considerably change their optical properties depending on experimental conditions. They are also very sensitive to molecular environment and external influences that can be used for multiple applications in different areas. Silicon nanostructures prepared by laser ablation show large perspectives for molecular sensing and biomedical applications. In this paper, an overview of optical properties of silicon nanostructures with focus on nanoparticles prepared by ultrafast laser ablation in liquids is provided. It is shown that they reveal wide prospects for applications in nanobiomedicine and their unique characteristics can be significantly enhanced due to laser-induced metal incorporation. Metal inclusions lead to appearance of plasmonic properties in semiconductor nanomaterials that can be applied for molecule detection using surface enhancing of optical response. [ABSTRACT FROM AUTHOR]

Contamination‐free silicon‐based nanoparticles (NPs) with several modalities are developed in this work. They are formed by non‐toxic laser‐assisted decomposition of silicon microgranules homogeneously dispersed in deionized water. Precise control of numerous experimental parameters allows repeatable fine tuning of nanoparticle size solving significant lacks of a direct laser ablation routine. Such a method provokes a huge amount of paramagnetic defect states of optically active silicon NPs that can serve as a contrast agent for magnetic resonance and nonlinear optical imaging. Perspectives of their bioapplication are driven by detected their fast size degradation in a NaCl‐based medium. Engineering of water soluble optically active silicon nanoparticles with numerous defect states are developed in this work. Laser decomposition of silicon microparticles can be successfully employed for their formation and for fine size tuning as well. Paramagnetic defect states of optically active silicon nanoparticles can serve as contrast agents for cell imaging and for size control during their dissolution in a NaCl medium. [ABSTRACT FROM AUTHOR]

Driven by surface cleanness and unique physical, optical and chemical properties, bare (ligand-free) laser-synthesized nanoparticles (NPs) are now in the focus of interest as promising materials for the development of advanced biomedical platforms related to biosensing, bioimaging and therapeutic drug delivery. We recently achieved significant progress in the synthesis of bare gold (Au) and silicon (Si) NPs and their testing in biomedical tasks, including cancer imaging and therapy, biofuel cells, etc. We also showed that these nanomaterials can be excellent candidates for tissue engineering applications. This review is aimed at the description of our recent progress in laser synthesis of bare Si and Au NPs and their testing as functional modules (additives) in innovative scaffold platforms intended for tissue engineering tasks. [ABSTRACT FROM AUTHOR]