A.S. Sarycheva

Combined Raman and atomic force microscopy study of hemoglobin distribution inside erythrocytes and nanoparticle localization on the erythrocyte surface

The letter describes a combined technique of atomic force microscopy (AFM) and micro-Raman spectroscopy (mRS) to estimate the distribution of cytosolic hemoglobin (Hb) and nanoparticles (NPs) inside and on the erythrocyte surface, respectively. We have shown that cytosolic hemoglobin is distributed uniformly inside the cell while NPs absorb on the cell surface irregularly, forming nanoaggregates. The obtained data provide new insight into the surface enhanced Raman spectroscopy of living cells.

Microbead silica decorated with polyhedral silver nanoparticles as a versatile component of sacrificial gel films for SERS applications

A new method of microbead silica preparation with superficially built-in 2–3 nm silver seeds is suggested by using a simple reaction of Stoeber SiO2 microspheres with hot aqueous solutions of diamminesilver(I) hydroxide without addition of reducing agents. The seeding beads initiate growth of polyhedral 20–50 nm silver nanoparticles encrusting silica surface after an instant heterogeneous contact with a mixture of silver nitrate and ascorbic acid solutions with concentrations of as low as 1 mM. The unique microstructure results in a pronounced, about 100 nm, red shift of the silver plasmonic band allowing fast and robust tuning of optical properties of the nanocomposites. Such microengineered building blocks are stored safely in a sacrificial biopolymer (ethylcellulose) film as its versatile component to be applied on demand in aqueous environment since polymer swelling absorbs water-soluble analytes and allows for the advanced SERS analysis.

A new route for SERS analysis of intact erythrocytes using polydisperse silver nanoplatelets on biocompatible scaffolds

Superior spectral sensitivity and functional abilities of anisotropic, instead of the usually used spherical, noble metal nanoparticles, allow development of new surface-enhanced Raman spectroscopy (SERS) approaches to analyse biological objects. We found and resolved for the first time the particular risks of survival of silver nanoparticles in different salines to succeed in recording the SERS spectra of intact erythrocytes as an important family of living cells. The ensemble of nanoplatelets with varied shapes and sizes grants multispectral absorption of laser irradiation since a fraction of the nanoparticles with a given position of a plasmonic band always exists in such a mixture, thereby providing an effective SERS amplification. At the same time, fast recrystallization of anisotropic silver nanoplatelets occurs in a standard chloride-based saline, being important to keep the erythrocytes alive but neglecting the benefits of the silver platelets as the most versatile and prospective components of SERS sensors. Substitution of chlorides with nitrates keeps both the intact cells and anisotropic nanoparticles safe on biocompatible cellulose SERS scaffolds containing the mixture of silver nanoplatelets thus promoting the development of new SERS devices for biomedical diagnostics.

Evaluation of toxicity of silver ions and nanoparticles using model bacteria with luminescent phenotype

It has been established using the model bacterial luminescence of the genetically modified bacteria Escherichia coli K12 TG1 that the damaging effect of silver nanoparticles (52 nm in size) developed more slowly and emerged at higher concentrations (approximately by 2 orders of magnitude) when compared with silver ions. A decline of bioluminescence and oxygen consumption is observed upon exposure to both nanoparticles and silver ions. Following the inhibition of biochemical processes, the silver bactericidal action (based on the ability to decrease the number of CFU) and morphological changes in the cells (according to the AFM data) are revealed. Similarly to the results of our previous studies on establishing the bactericidal effect of single-walled carbon nanotubes, the presented data allows us to suggest the use of bacterial luminescence changes for the primary assessment of the toxicity of silver nanoparticles.

Vapor phase sers sensor based on mesoporous silica decorated with silver nanoparticles

A. S. Sarycheva, A. A. Semenova, E. A. Goodilin2,3,∗ Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute, Drexel University, Philadelphia, PA 19104, USA Lomonosov Moscow State University, Faculty of Materials Science, Lenin Hills, Moscow, 119991, Russia Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences Sciences, Moscow, 119991, Russia *goodilin@yandex.ru