The peculiarities of the synthesis of spherical plasmonic nanoparticles with gold core and organosilica shell, as well as the chemisorption on them of maleimide derivatives of sulfocyanine-3 (SuCy3) and borondipyrromethene (BDP R6G), characterized by high and low fluorescence quantum yields, respectively, are discussed. Using SuCy3 as an example, the possibility of controlling the emission of fluorophores in composite nanoparticles by varying the grafting density of their molecules onto the organosilica shell, as well as its thickness, has been systematically studied. It is shown that fluorescence quenching is characteristic for particles with either a small shell thickness (4 nm) or a high density of dye grafting (the intermolecular distance is <= 2 nm). At the same time, in the range of shell thicknesses from 14 to 22 nm and at the distances between grafted dye molecules greater than 5 nm, there is a significant (up to 8-fold) fluorescence enhancement. In the case of BDP R6G, a significant increase in the dye stability upon its chemisorption on the nanoparticle surface is demonstrated.

The unique properties of metal nanoparticles (NPs) resulting from their localized surface plasmon resonance have led to the emergence and rapid development of promising scientific areas. One of these areas is thermoplasmonics, which is based on the ability of such NPs to effectively transform optical radiation into heat. We discuss the optical properties of noble metal NPs, the main approaches to their synthesis, as well as the latest advances of thermoplasmonics in the field of biomedicine. The focus of this review is on photothermal diagnostics and therapy (theranostics) of various diseases. Note that, in addition to theranostics of tumors, the prospects for the use of plasmonic NPs in cardiology, ophthalmology, the fight against bacterial and viral infections, and other biomedical fields have been analyzed.

Gold nanoparticles (GNPs) are promising radiosensitizers for cancer radiotherapy. Moreover, they can be used in the same way for radiation processing and sterilization. Such application of GNPs is of practical interest since it may significantly reduce the dose load and expand the application of radiation treatment. In the present study, the high radiosensitization effect of GNPs in relation to viral particles is demonstrated for the first time. The preparations of tobacco mosaic virus (TMV) are used as an experimental model, insofar as this virus has the same properties as animal and human ones but is safe for humans. Irradiation with 45 kVp X‐ray to the doses of 4 and 7 kGy leads to a decrease in the infectious activity of TMV virions up to 1.92‐ and 2.70‐fold, respectively. At the same time, irradiation in the presence of 0.4 mg mL −1 of 12 nm spherical GNPs increases the efficiency of virus inactivation up to 15‐ and 22‐fold. The GNPs enhance both the damage to capsid protein due to the enhanced generation of reactive oxygen species and genome RNA due to the emission of secondary radiation. These results show the great prospects of the application of high‐ Z nanoparticles in radiation treatment.

In this study we have probed the role of different enhancement mechanisms of the nanosensitizers in the X-ray irradiated oxygen-free model aqueous organic systems containing "bare " gold nanoparticles (AuNPs) using the spin-trapping technique with electron paramagnetic resonance detection. The observed enhancement effect was found to be ca. 1.67 wp(-1) for the AuNPs with an average diameter of 18 nm and 45 kVp X-rays. The comparison with Monte Carlo simulation shows that the sensitizing effect of AuNPs in the X-ray irradiated oxygen-free aqueous organic systems could be attributed to the increasing absorbed dose due to high absorption cross-section of gold atoms. It implies that the radiation-chemical yield of hydroxyl radicals responsible for the oxidative damage in the absence of oxygen remains virtually unchanged in the presence of AuNPs. Also, no clear evidence was found for the dose rate effects upon variation of this parameter by more than an order of magnitude (0.06-1.21 Gy/s). In practical sense, these results urge the development of new efficient approaches for the radiation treatment of hypoxic media using nanoparticles.& nbsp;& nbsp;

It has been found that the addition of ammonia water to a gold sol obtained by the Duff method induces the growth of the gold particles. The growth kinetics of such particles in alkaline solutions of ammonia and sodium hydroxide has been investigated. Using the modified Kolmogorov–Johnson–Mel–Avrami model, the aggregative mechanism of nanoparticle growth has been revealed for a system with the maximum NH3⋅H2O concentration, while a mixed mechanism, which includes the Ostwald ripening, has been found for other systems. It has been shown that the sizes and dispersity of the final particles can be controlled by varying the concentration of ammonia water and the time of preliminary incubation of an initial sol, while sodium hydroxide does not exhibit such ability. It has been assumed that the decomposition of gold–phosphine complexes, which stabilize the ultrafine particles, followed by the formation of gold–ammonia complexes is the most probable explanation for the action of ammonia water on the Duff sols.

Nanoparticles (NPs) with a high atomic number (Z) are promising radiosensitizers for cancer therapy. However, the dependence of their efficacy on irradiation conditions is still unclear. In the present work, 11 different metal and metal oxide NPs (from Cu (ZCu = 29) to Bi2O3 (ZBi = 83)) were studied in terms of their ability to enhance the absorbed dose in combination with 237 X-ray spectra generated at a 30–300 kVp voltage using various filtration systems and anode materials. Among the studied high-Z NP materials, gold was the absolute leader by a dose enhancement factor (DEF; up to 2.51), while HfO2 and Ta2O5 were the most versatile because of the largest high-DEF region in coordinates U (voltage) and Eeff (effective energy). Several impacts of the X-ray spectral composition have been noted, as follows: (1) there are radiation sources that correspond to extremely low DEFs for all of the studied NPs, (2) NPs with a lower Z in some cases can equal or overcome by the DEF value the high-Z NPs, and (3) the change in the X-ray spectrum caused by a beam passing through the matter can significantly affect the DEF. All of these findings indicate the important role of carefully planning radiation exposure in the presence of high-Z NPs.

Gold nanoparticles (GNPs) emerged as promising antitumor radiosensitizers. However, the complex dependence of GNPs radiosensitization on the irradiation conditions remains unclear. In the present study, we investigated the impacts of the dose rate and photon energy on damage of the pBR322 plasmid DNA exposed to X-rays in the presence of 12 nm, 15 nm, 21 nm, and 26 nm GNPs. The greatest radiosensitization was observed for 26 nm GNPs. The sensitizer enhancement ratio (SER) 2.74 ± 0.61 was observed at 200 kVp with 2.4 mg/mL GNPs. Reduction of X-ray tube voltage to 150 and 100 kVp led to a smaller effect. We demonstrate for the first time that the change of the dose rate differentially influences on radiosensitization by GNPs of various sizes. For 12 nm, an increase in the dose rate from 0.2 to 2.1 Gy/min led to a ~1.13-fold increase in radiosensitization. No differences in the effect of 15 nm GNPs was found within the 0.85–2.1 Gy/min range. For 21 nm and 26 nm GNPs, an enhanced radiosensitization was observed along with the decreased dose rate from 2.1 to 0.2 Gy/min. Thus, GNPs are an effective tool for increasing the efficacy of orthovoltage X-ray exposure. However, careful selection of irradiation conditions is a key prerequisite for optimal radiosensitization efficacy.

The features of (γ-mercaptopropyl)trimethoxysilane (MPTMS) hydrolytic condensation in alkaline aqueous solutions have been studied. The interrelation between the process time, MPTMS concentration, and structure-related morphological characteristics of the obtained organosilica (silsesquioxane) particles has been determined. It has been shown that toroidal particles are mainly formed at low precursor concentrations (≤2.5 mM) in a solution. The formation kinetics of such nanotoroids has been analyzed, and preliminary data have been obtained on the mechanism of this process. These data have been discussed taking into account the information available from the literature on the structure of silsesquioxanes and the role of disulfide bonds in the formation of anisotropic particles of these compounds.

The effect of the degree of anisotropy (axial ratio) of gold nanoparticles on the structure and conductivity of ring deposits formed on a planar substrate upon evaporation of droplets of aqueous dispersions with different particle number concentrations has been studied. A nontrivial phenomenon of a decrease in the specific conductivity of the deposits with an increase in particle concentration in case of gold nanorods dispersions has been revealed.

It has been shown for the first time that nanosized organosilica toroids can be formed via hydrolytic condensation of (γ-mercaptopropyl)trimethoxysilane in an alkaline medium. It has been found that such toroids may be used as “nuclei” for the synthesis of plasmonic composite nanoparticles with a core/shell structure.

Features of the evolution of ultrafine gold nanoparticles synthesized by the Duff method with temperature and time have been studied in relation to their use as seeds for the formation of plasmonic nanoshells. A quantitative relation has been revealed between the duration of preheating of such particles at a preset temperature and their size. The obtained relation indicates that Au nanoparticles grow mainly via the Ostwald ripening mechanism. Using anisotropic composite FeOOH/Ag particles as an example, it has been shown that the obtained information may be used to substantially decrease the duration of the synthesis of metal nanoshells on diverse cores.

It has been shown that citrate gold nanoparticles can be embedded (partly immersed) into the surface layers of different glassy polymers with subsequent seeded growth of the particles in an aqueous chloroauric acid–hydroxylamine mixed solution. Quantitative data have been obtained on the seeded growth kinetics, and it has been shown that its rate-limiting stage is the diffusion of metal ions from the bulk solution to the surface of gold nanoparticles.