Enhancing radioprotection: A chitosan-based chelating polymer is a versatile radioprotective agent for prophylactic and therapeutic interventions against radionuclide contamination

To mitigate the risk of radioactive isotope dissemination, the development of preventative and curative measures is of particular interest. For mass treatment, the developed solution must be easily administered, preferably orally, with effective, nontoxic decorporating properties against a wide range of radioactive isotopes. Currently, most orally administered chelation therapy products are quickly absorbed into the blood circulation, where chelation of the radioactive isotope is a race against time due to the short circulation half-life of the therapeutic. This report presents an alternative therapeutic approach by using a functionalized chitosan (chitosan@DOTAGA) with chelating properties that remains within the gastrointestinal tract and is eliminated in feces, that can protect against ingested radioactive isotopes. The polymer shows important in vitro chelation properties towards different metallic cations of importance, including (Cs(I), Ir(III), Th(IV), Tl(I), Sr(II), U(VI) and Co(II)), at different pH (from 1 to 7) representing the different environments in the gastrointestinal tract. An in vivo proof of concept is presented on a rodent model of uranium contamination following an oral administration of Chitosan@DOTAGA. The polymer partially prevents the accumulation of uranium within the kidneys (providing a protective effect) and completely prevents its uptake by the spleen.

In vitro and in vivo toxicity of carbon dots with different chemical compositions

Carbon dots (CDs) are easy-obtained nanoparticles with wide range of biological activity; however, their toxicity after prolonged exposure is poorly investigated. So, in vitro and in vivo toxicity of CDs with the surfaces enriched with hydroxylated hydrocarbon chains and methylene groups (CD_GE), carboxyl and phenol groups accompanied with nitrogen (CD_3011), trifluoromethyl (CDF19) or toluidine and aniline groups (CDN19) were aimed to be discovered. CDs' in vitro toxicity was assessed on A549 cells (real-time cell analysis of impedance, fluorescence microscopy) after 24 h of incubation, and we observed no changes in cell viability and morphology. CDs' in vivo toxicity was assessed on C57Bl6 mice after multiple dosages (5 mg/kg subcutaneously) for 14 days. Lethality (up to 50%) was observed in CDN19 and CD_3011 groups on different days of dosing, accompanied by toxicity signs in case of CD_3011. There were no changes in serum biochemical parameters except Urea (increased in CDF19 and CD_3011 groups), nor substantial kidney, liver, and spleen injuries. The most impactful for all organs were also CD_3011 and CDF19, causing renal tubule injury and liver blood supply violation. Thus, CDs with a surface enriched with oxygen- and nitrogen-containing functional groups might be toxic after multiple everyday dosing, without, however, significant damages of internal organs in survived animals.

A comparative multi-level toxicity assessment of carbon-based Gd-free dots and Gd-doped nanohybrids from coffee waste: hematology, biochemistry, histopathology and neurobiology study

Here, a comparative toxicity assessment of precursor carbon dots from coffee waste (cofCDs) obtained using green chemistry principles and Gd-doped nanohybrids (cofNHs) was performed using hematological, biochemical, histopathological assays in vivo (CD1 mice, intraperitoneal administration, 14 days), and neurochemical approach in vitro (rat cortex nerve terminals, synaptosomes). Serum biochemistry data revealed similar changes in cofCDs and cofNHs-treated groups, i.e. no changes in liver enzymes' activities and creatinine, but decreased urea and total protein values. Hematology data demonstrated increased lymphocytes and concomitantly decreased granulocytes in both groups, which could evidence inflammatory processes in the organism and was confirmed by liver histopathology; decreased red blood cell-associated parameters and platelet count, and increased mean platelet volume, which might indicate concerns with platelet maturation and was confirmed by spleen histopathology. So, relative safety of both cofCDs and cofNHs for kidney, liver and spleen was shown, whereas there were concerns about platelet maturation and erythropoiesis. In acute neurotoxicity study, cofCDs and cofNHs (0.01 mg/ml) did not affect the extracellular level of L-[14C]glutamate and [3H]GABA in nerve terminal preparations. Therefore, cofNHs demonstrated minimal changes in serum biochemistry and hematology assays, had no acute neurotoxicity signs, and can be considered as perspective biocompatible non-toxic theragnostic agent.

Bio-distribution of Carbon Nanoparticles Studied by Photoacoustic Measurements

Carbon-based nanomaterials are promising for a wide range of biomedical applications, i.e. drug delivery, therapy, and imaging including photoacoustic tomography, where they can serve as contrast agents, biocompatibility and biodistribution of which should be assessed before clinical setting. In this paper, localization of carbon flurooxide nanoparticles, carbon nanodots from β-alanine, carbon nanodots from urea and citric acid and glucose-ethylenediamine nanoparticles (NPs) in organs of Wistar rats were studied by photoacoustic measurements after 24 h of their intravenous injection. 16 ns light pulse from a Q-switched Nd:YAG laser with 1064 nm wavelength was used as an excitation source. The laser-induced photoacoustic signals were recorded with a ring piezoelectric detector. Light absorption by carbon NPs resulted in noticeable enhancement of the photoacoustic amplitude in the tissues where the NPs were accumulated. The NPs were preferably accumulated in liver, kidneys and spleen, and to a lesser extent in heart and gastrocnemius muscles. Together with remarkable fluorescent properties of the studied carbon nanomaterials, their photoacoustic responses allow their application for bi-modal fluorescence-photoacoustic bio-imaging.

Chlorophyll fluorometry in evaluating photosynthetic performance: key limitations, possibilities, perspectives and alternatives

Non-destructive methods for the assessment of photosynthetic parameters of plants are widely applied to evaluate rapidly the photosynthetic performance, plant health, and shifts in plant productivity induced by environmental and cultivation conditions. Most of these methods are based on measurements of chlorophyll fluorescence kinetics, particularly on pulse modulation (PAM) fluorometry. In this paper, fluorescence methods are critically discussed in regard to some their possibilities and limitations inherent to vascular plants and microalgae. Attention is paid to the potential errors related to the underestimation of thylakoidal cyclic electron transport and anoxygenic photosynthesis. PAM-methods are also observed considering the color-addressed measurements. Photoacoustic methods are discussed as an alternative and supplement to fluorometry. Novel Fourier modifications of PAM-fluorometry and photoacoustics are noted as tools allowing simultaneous application of a dual or multi frequency measuring light for one sample.

Photo- and Radiofrequency-Induced Heating of Photoluminescent Colloidal Carbon Dots

Nitrogen- and oxygen-containing carbon nanoparticles (O, N-CDs) were prepared by a facile one-step solvothermal method using urea and citric acid precursors. This method is cost-effective and easily scalable, and the resulting O, N-CDs can be used without additional functionalization and sample pretreatment. The structure of O, N-CDs was characterized by TEM, AFM, Raman, UV-vis, and FTIR spectroscopies. The obtained O, N-CDs with a mean diameter of 4.4 nm can be easily dispersed in aqueous solutions. The colloidal aqueous solutions of O, N-CDs show significant photothermal responses under red-IR and radiofrequency (RF) irradiations. The as-prepared O, N-CDs have a bright temperature-dependent photoluminescence (PL). PL/PLE spectral maps were shown to be used for temperature evaluation purposes in the range of 30–50 °C. In such a way, the O, N-CDs could be used for biomedicine-related applications such as hyperthermia with simultaneous temperature estimation with PL imaging.

A scientometric analysis of agricultural pollution by using bibliometric software VoSViewer and Histcite™

While modern agriculture brings more food to people, it causes environmental pollution as well. Agricultural pollution has attracted extensive public attention. A lot of reviews on agricultural research were conducted from different research aspects, but there is a lack of work on analyzing the research trend from large volumes of publications in the field of agricultural pollution. In the present work, a scientometric analysis of agricultural pollution was conducted to fill the gap by using the software of VoSviewer and HistCite™. The datasets are collected from the core database of Web of Science from 1991 to 2019, totally 1338 records on the topic of agricultural pollutions. In most years (1996, 1999, 2002, 2006, 2009, 2011, and 2013), the total local citation score (TLCS) and total global citation score (TGCS) have coincident peaks. Zhang, Ju, and Zhu have the highest TLCS and TGCS. In terms of institutes, Chinese Acad Sci and China Agr Univ are the leading institutes in this field. The Univ Calif Davis, INRA, and USDA ARS have very high global impacts. From the research hot topics, the representative words include "soil," "agriculture," "contamination," "environment," "lead," and "balance." Representative words like "heavy-metals," "groundwater," "land-use," and "water" are emerging in the latter time period. Five leading research co-cited reference clusters are identified, including environment management, underground water, monitoring and alarming for the agriculture-environment standards, intrinsic mechanism to the circulatory system, and ecology system and land use. The recent trend is revealed from the bibliographical-coupling network, focusing on classical and old-fashion research, like pollution chemicals including N management, pesticides, and heavy metal. This work provides a holistic picture on the research in the field of agriculture pollution.

High levels of anoxygenic photosynthesis revealed by dual-frequency Fourier photoacoustics in Ailanthus altissima leaves

In contrast to oxygenic photosynthesis, true anoxygenic photosynthesis is not associated with O2 evolution originated from water photolysis but still converts light energy to that of the phosphoanhydride bonds of ATP. In a narrow sense, anoxygenic photosynthesis is mainly known as to be related to the purple and green sulfur bacteria, but in a broad sense, it also occurs in the vascular plants. The portion of photosynthetic water photolysis that is compensated by the processes of O2 uptake (respiration, photorespiration, Mehler cycle, etc.) may be referred to as 'quasi' anoxygenic photosynthesis. Photoacoustic method allows for the separate detection of photolytic O2 at frequencies of measuring light about 20-40Hz, whereas at 250-400Hz, it detects the photochemical energy storage. We have developed a fast-Fourier transform photoacoustic method enabling measurements of both these signals simultaneously in one sample. This method allows to calculate oxygenic coefficients, which reflect the part of photochemically stored light energy that is used for the water photolysis. We show that the true anoxygenic photosynthesis in Ailanthus altissima Mill. leaves reached very high levels under low light, under moderate light at the beginning of the 1-h period, and at the end of the 40-min period under saturating light.

Application of the Photoacoustic Approach in the Characterization of Nanostructured Materials

A new generation of sensors can be engineered based on the sensing of several markers to satisfy the conditions of the multimodal detection principle. From this point of view, photoacoustic-based sensing approaches are essential. The photoacoustic effect relies on the generation of light-induced deformation (pressure) perturbations in media, which is essential for sensing applications since the photoacoustic response is formed due to a contrast in the optical, thermal, and acoustical properties. It is also particularly important to mention that photoacoustic light-based approaches are flexible enough for the measurement of thermal/elastic parameters. Moreover, the photoacoustic approach can be used for imaging and visualization in material research and biomedical applications. The advantages of photoacoustic devices are their compact sizes and the possibility of on-site measurements, enabling the online monitoring of material parameters. The latter has significance for the development of various sensing applications, including biomedical ones, such as monitoring of the biodistribution of biomolecules. To extend sensing abilities and to find reliable measurement conditions, one needs to clearly understand all the phenomena taking place during energy transformation during photoacoustic signal formation. Therefore, the current paper is devoted to an overview of the main measurement principles used in the photoacoustic setup configurations, with a special focus on the key physical parameters.

Impact of Carbon Fluoroxide Nanoparticles on Cell Proliferation

Cytotoxicity of fluorescent carbon fluoroxide (CFO) nanoparticles (NPs) was studied in a label-free manner on several cancer and non-cancer cell lines. A direct cytotoxic effect of the CFO NPs was clearly observed by a suppression of cell proliferation. The real-time measurement of cell activities allowed to quantify the impact of the uptaken NPs on cell proliferation and after washout of the NPs from the cell culture medium. The results show more toxic effects of the CFO NPs on cancer than on non-cancer cell lines. The notion of NPs biocompatibility must be related to a maximum concentration value of the NPs acceptable for a given cell type. Furthermore, the cytotoxicity effects of NPs should be studied not only during their direct exposure to cells but also after their washout from the culture medium.

Photoluminescent Recognition of Strong Alcoholic Beverages with Carbon Nanoparticles

A simple sensitive method for nonspecific recognition of armagnac, cognac, whiskey, and ethanol/water mixture was developed by using photoluminescence (PL) of carbon nanoparticles (NPs). The carbon NPs were synthesized from the mixture of urea and anhydrous citric acid, followed by few annealing processes to achieve the full effect by solvothermal carbonization. PL features of carbon NPs depend on the alcohol environments in which the NPs are dispersed. PL/PL excitation maps of the alcoholic beverages were mathematically treated, and a final principal component analysis diagram allows visualization of different clusters corresponding to each beverage. The optimal measurement conditions (concentration of NPs in colloidal solution and excitation wavelength) were defined to ensure a reliable recognition level.

Intracellular Detection and Localization of Nanoparticles by Refractive Index Measurement

The measuring of nanoparticle toxicity faces an important limitation since it is based on metrics exposure, the concentration at which cells are exposed instead the true concentration inside the cells. In vitro studies of nanomaterials would benefit from the direct measuring of the true intracellular dose of nanoparticles. The objective of the present study was to state whether the intracellular detection of nanodiamonds is possible by measuring the refractive index. Based on optical diffraction tomography of treated live cells, the results show that unlabeled nanoparticles can be detected and localized inside cells. The results were confirmed by fluorescence measurements. Optical diffraction tomography paves the way to measuring the true intracellular concentrations and the localization of nanoparticles which will improve the dose-response paradigm of pharmacology and toxicology in the field of nanomaterials.

Effects of Zinc Oxide Nanoparticles on Physiological and Anatomical Indices in Spring Barley Tissues

The aim of the present work was to investigate the toxic effects of zinc oxide nanoparticles (ZnO NPs, particle size < 50 nm) on the physiological and anatomical indices of spring barley (Hordeum sativum L.). The results show that ZnO NPs inhibited H. sativum growth by affecting the chlorophyll fluorescence emissions and causing deformations of the stomatal and trichome morphology, alterations to the cellular organizations, including irregularities of the chloroplasts, and disruptions to the grana and thylakoid organizations. There was a lower number of chloroplasts per cell observed in the H. sativum leaf cells treated with ZnO NPs as compared to the non-treated plants. Cytomorphometric quantification revealed that ZnO NPs decreased the size of the chloroplast by 1.5 and 4 times in 300 and 2000 mg/L ZnO NP-treated plants, respectively. The elemental analysis showed higher Zn accumulation in the treated leaf tissues (3.8 and 10.18-fold with 300 and 2000 mg/L ZnO NPs, respectively) than the untreated. High contents of Zn were observed in several spots in ZnO NP-treated leaf tissues using X-ray fluorescence. Deviations in the anatomical indices were significantly correlated with physiological observations. The accumulation of Zn content in plant tissues that originated from ZnO NPs was shown to cause damage to the structural organization of the photosynthetic apparatus and reduced the photosynthetic activities.

Chlorophyll fluorescence kinetics and oxygen evolution in Chlorella vulgaris cells: Blue vs. red light

Oxygen evolution and chlorophyll fluorescence kinetics in cells of the Chlorella vulgaris strain (Europolytest, Russia) were studied under low, moderate and high photosynthetic photon flux densities (PPFD 40, 130 and 350 μmol photons m^-2 s^-1) of the red and blue actinic light. A novel method of a pulse amplitude modulated (PAM) Fourier chlorophyll fluorometry was applied to obtain photoinduction curves simultaneously for the red and blue measuring light for one sample. It was found that the red light did not induce oxygen evolution at low and moderate PPFD, whereas at high PPFD it caused a declining oxygen release. There was only a trace fluorescence kinetics at the low PPFD, but noticeable fluorescence kinetics under the red light was observed at the low and moderate PPFD. Particularly, the moderate red illumination of Chlorella cells excited a high chlorophyll fluorescence kinetics along with the absence of oxygen evolution that suggests anoxygenic photosynthesis. In contrast, the blue light induced a significant oxygen evolution as well as fluorescence kinetics already at low PPFD which were both further increased with the PPFD increasing. In addition, a high value of the chromatic divergence of quantum yield of photosystem II was revealed between the red and blue measuring light under high PPFD of the red actinic light.

Unique features of brain metastases-targeted AGuIX nanoparticles vs their constituents: A focus on glutamate-/GABA-ergic neurotransmission in cortex nerve terminals

Gadolinium-based radiosensitizing AGuIX nanoparticles (AGuIX) currently tested two phase 2 clinical trials in association with radiotherapy for the treatment of brain metastases. Here, excitatory/inhibitory neurotransmission was assessed in rat cortex nerve terminals in the presence of AGuIX and their constituents (DOTAGA and DOTAGA/Gd³⁺) at concentrations used for medical treatment, and those 5-24 times higher. The ambient level, transporter-mediated, tonic and exocytotic release of L-[¹⁴C]glutamate and [³H]GABA, the membrane potential of nerve terminals were not changed in the presence of AGuIX at concentrations used for medical treatment ([Gd³⁺] = 0.25 mM, corresponding to 0.25 g.L^-1), and DOTAGA (0.25 mM) and DOTAGA/Gd³⁺ (0.25 mM/0.01 mM). Difference between AGuIX and the precursors was uncovered, when their concentrations were increased. AGuIX (1.25-6 mM) did not change any transport characteristics of L-[¹⁴C]glutamate and [³H]GABA, whereas, DOTAGA (1.25-6 mM) affected the membrane potential, ambient level, and exocytotic release of L-[¹⁴C]glutamate and [³H]GABA. Gd³⁺ did not mask, but even enhanced above effects of DOTAGA. Therefore, AGuIX did not influence glutamate- and GABA-ergic neurotransmission at the presynaptic site. In contrast, DOTAGA and mixture DOTAGA/Gd³⁺ significantly affected synaptic neurotransmission at high concentrations. AGuIX own structure that overcomes neurotoxic features of their constituents.

Kinetics of Hydrogen Generation from Oxidation of Hydrogenated Silicon Nanocrystals in Aqueous Solutions

Hydrogen generation rate is one of the most important parameters which must be considered for the development of engineering solutions in the field of hydrogen energy applications. In this paper, the kinetics of hydrogen generation from oxidation of hydrogenated porous silicon nanopowders in water are analyzed in detail. The splitting of the Si-H bonds of the nanopowders and water molecules during the oxidation reaction results in powerful hydrogen generation. The described technology is shown to be perfectly tunable and allows us to manage the kinetics by: (i) varying size distribution and porosity of silicon nanoparticles; (ii) chemical composition of oxidizing solutions; (iii) ambient temperature. In particular, hydrogen release below 0 °C is one of the significant advantages of such a technological way of performing hydrogen generation.

Silicon-Based Optoelectronic Tongue for Label-Free and Nonspecific Recognition of Vegetable Oils

A special electronic tongue system based on photoelectric measurements on Si-Si/SiN X sensitive structures is reported. The sensing approach is based on measuring of minority carrier lifetime in silicon-based substrates using microwave-detected photoconductance decay. This inexpensive and environmentally friendly combinatorial electronic sensing platform is able to create characteristic electronic fingerprints of liquids, detect, and recognize them. In particular, an application of the optoelectronic tongue for recognition of vegetable oils and their mixtures is described.

Photo-induced cubic-to-hexagonal polytype transition in silicon nanowires

Crystalline phase transformation in silicon nanowires from cubic diamond to hexagonal diamond under strong laser excitation, caused by inhomogeneous heating-induced mechanical stresses.

Toxicity of copper oxide nanoparticles on spring barley (Hordeum sativum distichum)

The rapid growth of copper oxide nanoparticles (CuO NPs) production and its abundant uses in many industries, and increasing release into an environment from both intentional and unintentional sources, create risks to spring barley (Hordeum sativum distichum), one of the most important staple food crop. Thereby, the aim of this study was to investigate the phytotoxicity of CuO NPs on H. sativum growth in hydroponic system. The CuO NPs inhibited H. sativum growth by affecting the germination rate, root and shoot lengths, maximal quantum yield of photosystem II, and transpiration rate. Structural and ultrastructural examination of H. sativum tissues using light, transmission and scanning electron microscopy showed effects on stomatal aperture and root morphology, metaxylem size and changes in cellular organelles (plastids, mitochondria), as well as in plastoglobules, starch granules, protoplasm, and membranes. The formation of electron-dense materials was noted in the intercellular space of cells of CuO NPs-treated plants. In addition, relative root length was one-third (35%) that of the control, and relative shoot length (10%) was also reduced. Further, the Cu content of roots and leaves of CuO NPs-treated plants was 5.7 and 6.4-folds higher than the control (without CuO NPs), respectively. Presented data were significant at p ≤ 0.05 compared to control. Conclusively, the results provide insights into our understanding of CuO NPs toxicity on H. sativum, and findings could be used for developing strategies for safe disposal of NPs.

Live-stream characterization of cadmium-induced cell death using visible CdTe-QDs

Characterization of cell death currently requires the use of indirect markers, which has largely limited the ability to monitor cell death processes inside the cell. Here, we introduce a new method for the characterization of cell death mechanisms using cadmium telluride quantum dots (CdTe-QDs). Using visible CdTe-QDs with mesenchymal cells (e.g. synoviocytes), live-stream imaging allowed for visualization of cadmium-induced cell death, combining characteristics of apoptosis and autophagy. Initially, similar anti-proliferative effect was observed between 10 µg/ml Cd²⁺ and CdTe-QDs at 24 h (cell index/cell density ratio decreased from 0.6 to −16.6, p < 0.05) using techniques that do not require the capacity of CdTe-QDs. Apoptosis was confirmed by the quantification of morphological parameters (reduced surface area, increased cell thickness) and positive labeling with annexin V. Autophagy was confirmed by monodansylcadaverine staining, identifying similar autophagic vacuoles with both Cd²⁺ and CdTe-QD. However, QD imaging allowed for visualization of cadmium elements inside cell structures and their kinetic changes leading to cell death. Cell death characteristics were similar in inflammatory and non-inflammatory environment but were induced up to 4 h earlier in the former. Therefore, live-stream imaging of a visible cytotoxic agent has useful applications not currently possible with indirect methods, including chronological monitoring of cell death.

Size and Surface Chemistry Tuning of Silicon Carbide Nanoparticles

Chemical transformations on the surface of commercially available 3C-SiC nanoparticles were studied by means of FTIR, XPS, and temperature-programmed desorption mass spectrometry methods. Thermal oxidation of SiC NPs resulted in the formation of a hydroxylated SiO₂ surface layer with C₃Si-H and CH_x groups over the SiO₂/SiC interface. Controllable oxidation followed by oxide dissolution in HF or KOH solution allowed the SiC NPs size tuning from 17 to 9 nm. Oxide-free SiC surfaces, terminated by hydroxyls and C₃Si-H groups, can be efficiently functionalized by alkenes under thermal or photochemical initiation. Treatment of SiC NPs by HF/HNO₃ mixture produces a carbon-enriched surface layer with carboxylic acid groups susceptible to amide chemistry functionalization. The hydroxylated, carboxylated, and aminated SiC NPs form stable aqueous sols.

Anti-inflammatory and antioxidant effect of cerium dioxide nanoparticles immobilized on the surface of silica nanoparticles in rat experimental pneumonia

A massage with the potent counter-inflammatory material, cerium dioxide nanoparticles, is promising and the antioxidant properties of CeO₂ are considered the main, if not the only, mechanism of this action. Nevertheless, the elimination of ceria nano-particles from the organism is very slow and there is a strong concern for toxic effect of ceria due to its accumulation. To overcome this problem, we engineered a combined material in which cerium nanoparticles were immobilized on the surface of silica nanoparticles (CeO₂ NP), which is shown to be easily removed from an organism and could be used as carriers for nano-ceria. In our study particle size was 220±5nm, Zeta-potential -4.5mV (in water), surface charge density -17.22μC/cm² (at pH 7). Thirty-six male Wistar rats, 5 months old and 250-290g were divided into four groups: 1) control; 2) CeO₂ NP treatment; 3) experimental pneumonia (i/p LPS injection, 1mg/kg); and 4) experimental pneumonia treated with CeO₂ NP (4 times during the study in dosage of 0.6mg/kg with an orogastric catheter). Gas exchange and pulmonary ventilation were measured four times: 0, 1, 3 and 24h after LPS injection in both untreated and CeO₂ NP-treated animals. The mRNA of TNF-α, Il-6, and CxCL2 were determined by RT-PCR. ROS-generation in blood plasma and lung tissue homogenates were measured by means of lucigenin- and luminol-enhanced chemiluminescence. Endotoxemia in the acute phase was associated with: (1) pathological changes in lung morphology; (2) increase of ROS generation; (3) enhanced expression of CxCL2; and (4) a gradual decrease of VO₂ and V_E. CeO2 NP treatment of intact animals did not make any changes in all studied parameters except for a significant augmentation of VO₂ and V_E. CeO₂ NP treatment of rats with pneumonia created positive changes in diminishing lung tissue injury, decreasing ROS generation in blood and lung tissue and decreasing pro-inflammatory cytokine expression (TNF-α, Il-6 and CxCL2). Oxygen consumption in this group was increased compared to the LPS pneumonia group. In our study we have shown anti-inflammatory and antioxidant effects of CeO₂ NP. In addition, this paper is the first to report that CeO₂ NP stimulates oxygen consumption in both healthy rats, and rats with pneumonia. We propose the key in understanding the mechanisms behind the phenomena lies in the property of CeO₂ NP to scavenge ROS and the influence of this potent antioxidant on mitochondrial function. The study of biodistribution and elimination of СеО₂NP is the purpose of our ongoing study.

Cytotoxicity control of silicon nanoparticles by biopolymer coating and ultrasound irradiation for cancer theranostic applications

Silicon nanoparticles (SiNPs) prepared by mechanical grinding of luminescent porous silicon were coated with a biopolymer (dextran) and investigated as a potential theranostic agent for bioimaging and sonodynamic therapy. Transmission electron microscopy, photoluminescence and Raman scattering measurements of dextran-coated SiNPs gave evidence of their enhanced stability in water. In vitro experiments confirmed the lower cytotoxicity of the dextran-coated NPs in comparison with uncoated ones, especially for high concentrations of about 2 mg ml^-1. Efficient uptake of the NPs by cancer cells was found using bioimaging in the optical transmittance and photoluminescence modes. Treatment of the cells with uptaken SiNPs by therapeutic ultrasound for 5-20 min resulted in a strong decrease in the number of living cells, while the total number of cells remained nearly unchanged. The obtained data indicate a 'mild' effect of the combined action of ultrasonic irradiation and SiNPs on cancer cells. The observed results reveal new opportunities for controlling the photoluminescent and sonosensitizing properties of silicon-based NPs for applications in the diagnostics and mild therapy of cancer.

Folate-modified silicon carbide nanoparticles as multiphoton imaging nanoprobes for cancer-cell-specific labeling

SHG-active SiC nanoparticles were modified with folic acid for cancer-cell-specific labelling.

Optical Addressing Electronic Tongue Based on Low Selective Photovoltaic Transducer with Nanoporous Silicon Layer

The electronic tongue based on the array of low selective photovoltaic (PV) sensors and principal component analysis is proposed for detection of various alcohol solutions. A sensor array is created at the forming of p-n junction on silicon wafer with porous silicon layer on the opposite side. A dynamical set of sensors is formed due to the inhomogeneous distribution of the surface recombination rate at this porous silicon side. The sensitive to molecular adsorption photocurrent is induced at the scanning of this side by laser beam. Water, ethanol, iso-propanol, and their mixtures were selected for testing. It is shown that the use of the random dispersion of surface recombination rates on different spots of the rear side of p-n junction and principal component analysis of PV signals allows identifying mentioned liquid substances and their mixtures.

Electrochemical synthesis of luminescent ferrous fluorosilicate hexahydrate (FeSiF6·6H2O) nano-powders

Electrochemical etching of metallurgical FeSi₂/Si substrate produces ferrous fluorosilicate hexahydrate (FeSiF₆·6H₂O) nano-powder with strong and stable photoluminescence.

Determining the impact of hydrofluoric acid on surface states of as-prepared and chemically modified Si nanocrystals

The paper demonstrates an easy and cheap approach to chemical functionalization of silicon nanocrystal surface leading to enhancement of photoluminescence and electrical transport properties.

Carbon fluoroxide nanoparticles as fluorescent labels and sonosensitizers for theranostic applications

Carbon fluoroxide (CFO) nanoparticles (NPs) produced from silicon carbide wafers are used as both fluorescent probes and sonosensitizers for theranostic application. In vitro cell tests were carried out to investigate the feasibility of ultrasound-based therapy with the use of the CFO NPs. The NPs that penetrated inside the cells were shown to provoke cell destruction after application of an ultrasound treatment. No significant toxic effect was observed when the cells were treated with NP concentrations up to 0.5 mg ml^-1 without applying ultrasound treatment. The obtained results open a new way toward cancer therapy strategies.

Delivery of SiC-based nanoparticles into live cells driven by cell-penetrating peptides SAP and SAP-E

Cell-penetrating peptides enhance nanoparticle delivery into cells most efficiently if surface and peptide functional groups “match” to form non-covalent conjugates.

Might silicon surface be used for electronic tongue application?

An electronic tongue concept based on 2D mapping of photogenerated charge carrier lifetimes in silicon put in contact with different liquids is reported. Such method based on intrinsic sensitivity of the silicon surface states to the surrounding studied liquids allows creation of their characteristic electronic fingerprints. To increase recognition reliability, a set of characteristic fingerprints for a given liquid/silicon interface is proposed to be recorded at different bias voltages. The applicative potential of our sensing concept was demonstrated for different spirits and water samples.

Trypsinization-dependent cell labeling with fluorescent nanoparticles

Trypsin is often used to detach adhered cell subculture from a substrate. However, the proteolytic activity of trypsin may harm cells by cleaving the cell membrane proteins. The present study shows that cellular uptake of fluorescent nanoparticles is remarkably increased within 24 h after trypsinization. These results highlight the trypsin-induced protein digestion, provoking leaky cell plasma membrane which leads to the strongly enhanced cellular uptake of the nanoparticles. To prevent this effect, one should expose cells to the nanoparticle (NP)-based fluorescent labels at least 48 h after trypsinization.

Different-Oxides Nanoceramics Microhardness

With help of the method of the spark plasma sintering (SPS), the fine-grained (of micron approximately) ceramics based on various alumina nanopowders had created. A comparison of microhardness of ceramic samples obtained from 11 alumina nanopowders and 2 their composites was held. Microhardness of the ceramics obtained both by SPS, and by the traditional method (at successive pressing and sintering) is compared. The dependence of ceramics microhardness on the phase composition of the initial nanopowder and the average size of its particles was investigated. Besides alumina nanopowders ( Al 2 O 3), there were compared microhardness of ceramics from other 10 nanopowders of oxides ( SiO 2, ZnO , Fe 3 O 4, Gd 2 O 3, CuO , WO 3, TiO 2, Y 2 O 3, ZrO 2, MgO ) obtained both by SPS, and by the traditional method. It is obtained that the microhardness of the ceramics created on the method of the spark plasma sintering, is significantly higher than a microhardness of the ceramics obtained by the traditional method; at the SPS method the average size of grain in ceramics decreases (to 1 micron and less).

Impact of cell division on intracellular uptake and nuclear targeting with fluorescent SiC-based nanoparticles

Semiconductor nanoparticles (NPs) became important and wide-used tool for cell imaging because of their unique remarkable properties. Nevertheless, all previous investigations in this area were done on proliferating cells. For the first time, this work demonstrates strong influence of cell active proliferation/contact inhibition of proliferation on uptake of NPs. In addition, we show that cell division plays key-role in penetration of silicon carbide based NPs (SiC NPs) inside the cell nucleus. This may very likely concern other types of NPs able to reach the cell nuclei. In particular, observed effect of cell division gives perspectives for future selective cancer treatment with NPs.

Plasmon-enhanced nonlinear optical properties of SiC nanoparticles

An original plasmonic nano-Ag/SiN(x) substrate was elaborated to strongly enhance the nonlinear response of SiC NPs for the first time. A plasmon-induced two order of magnitude increase of second-harmonic generation and two-photon excited photoluminescence was experimentally achieved. The measured enhancement factors were correlated with local field intensities theoretically estimated by finite-difference time-domain calculations. The obtained plasmon-enhanced nonlinear response of the SiC nanostructures make them promising in nonlinear optics applications.

Nanostructured silicon nitride thin films for label-free multicolor luminescent cell imaging

The application of nanostructured luminescent silicon nitride (SiN(X)) thin films for label-free cell imaging is reported for the first time. Different strong local fields ensured by various molecules concentrated in various cell compartments can lead to the creation of preferential electronic conditions for radiative recombination of photogenerated charge carriers via a given electronic channel. Thus, highly contrasted multicolor luminescent cell imaging under one photon excitation becomes possible. The described label-free bio-imaging approach has good compatibility with fluorescence optical microscopy, and allows rapid and efficient cell imaging and cell line recognition.

Charge-driven selective localization of fluorescent nanoparticles in live cells

Covalent grafting of amino groups onto the carboxylic acid functionalities, naturally covering the surface of fluorescent nanoparticles produced from silicon carbide (SiC NPs), allowed tuning of their surface charge from negative to highly positive. Incubating 3T3-L1 fibroblast cells with differently charged SiC NPs demonstrates the crucial role of the charge in cell fluorescent targeting. Negatively charged SiC NPs concentrate inside the cell nuclei. Close to neutrally charged SiC NPs are present in both cytoplasm and nuclei while positively charged SiC NPs are present only in the cytoplasm and are not able to move inside the nuclei. This effect opens the door for the use of SiC NPs for easy and fast visualization of long-lasting biological processes taking place in the cell cytosol or nucleus as well as providing a new long-term cell imaging tool. Moreover, here we have shown that the interaction between charged NPs and nuclear pore complex plays an essential role in their penetration into the nuclei.

Evaluation of mesoporous silicon thermal conductivity by electrothermal finite element simulation

The aim of this work is to determine the thermal conductivity of mesoporous silicon (PoSi) by fitting the experimental results with simulated ones. The electrothermal response (resistance versus applied current) of differently designed test lines integrated onto PoSi/silicon substrates and the bulk were compared to the simulations. The PoSi thermal conductivity was the single parameter used to fit the experimental results. The obtained thermal conductivity values were compared with those determined from Raman scattering measurements, and a good agreement between both methods was found. This methodology can be used to easily determine the thermal conductivity value for various porous silicon morphologies.

Photoacoustic effects in nanocomposite structure 'porous silicon-liquid'

Photoacoustic effect in nanocomposite structure 'porous silicon-liquid' has been investigated. Main mechanisms involved in the formation of photoacoustic signal in such structures have been experimentally studied. Liquids with different viscosity (ethanol and acetone) filling the nanopores have been used. A proposed mathematical model describing the photoacoustic signal formation was found to be in good agreement with the experimental results. The role of thermally induced pressures provoked by the liquids confined inside the nanopores in the photoacoustic process has been analyzed.

Fluorescence kinetic parameters and cyclic electron transport in guard cell chloroplasts of chlorophyll-deficient leaf tissues from variegated weeping fig (Ficus benjamina L.)

Residual chlorophyll in chlorophyll-deficient (albino) areas of variegated leaves of Ficus benjamina originates from guard cell chloroplasts. Photosynthetic features of green and albino sectors of F. benjamina were studied by imaging the distribution of the fluorescence decrease ratio Rfd within a leaf calculated from maximum (Fm) and steady-state leaf chlorophyll fluorescence (Fs) at 690 and 740 nm. Local areas of albino sectors demonstrated an abnormally high Rfd(740)/Rfd(690) ratio. Fluorescence transients excited in albino sectors at red (640 and 690 nm) wavelengths showed an abrupt decrease of the Rfd values (0.4 and 0.1, correspondingly) as compared with those excited at blue wavelengths (1.7-2.4). This "Red Drop" was not observed for green sectors. Normal and chlorophyll-deficient leaf sectors of F. benjamina were also tested for linear and cyclic electron transport in thylakoids. The tests have been performed studying fluorescence at a steady-state phase with CO(2)-excess impulse feeding, photoacoustic signal generated by pulse light source at wavelengths selectively exciting PSI, fluorescence kinetics under anaerobiosis and fluorescence changes observed by dual-wavelength excitation method. The data obtained for albino sectors strongly suggest the possibility of a cyclic electron transport simultaneously occurring in guard cell thylakoids around photosystems I and II under blue light, whereas linear electron transport is absent or insufficient.

Vapor phase mediated cellular uptake of sub 5 nm nanoparticles

Nanoparticles became an important and wide-used tool for cell imaging because of their unique optical properties. Although the potential of nanoparticles (NPs) in biology is promising, a number of questions concerning the safety of nanomaterials and the risk/benefit ratio of their usage are open. Here, we have shown that nanoparticles produced from silicon carbide (NPs) dispersed in colloidal suspensions are able to penetrate into surrounding air environment during the natural evaporation of the colloids and label biological cells via vapor phase. Natural gradual size-tuning of NPs in dependence to the distance from the NP liquid source allows progressive shift of the fluorescence color of labeled cells in the blue region according to the increase of the distance from the NP suspension. This effect may be used for the soft vapor labeling of biological cells with the possibility of controlling the color of fluorescence. However, scientists dealing with the colloidal NPs have to seriously consider such a NP's natural transfer in order to protect their own health as well as to avoid any contamination of the control samples.

Size tuning of luminescent silicon nanoparticles with meso-porous silicon membranes

Size tuning of silicon (Si) nanoparticles (NPs) with the use of meso-porous silicon (meso-PS) free-standing layers is reported for the first time. Accumulation of Si NPs inside the membrane pores during the filtering process (NP transport through the meso-PS) leads to an auto-filtration effect (called Si-by-Si (SBS) filtration) allowing more efficient size selection of the NPs. General complex fractal shape and surface chemistry of the whole porous network, layer thickness as well as a given initial NP size dispersion determine final size of the NPs in the filtered solution. Moreover, quantum of step-like NP size increasing equal to 0.12 nm was found.

Strong photoluminescence enhancement of silicon quantum dots by their near-resonant coupling with multi-polar plasmonic hot spots

Localization of quantum dots (QDs) in the vicinity of metal nanoparticles (NPs) is known as one of the most efficient ways to increase their photoluminescence (PL). Despite the important recent advances achieved in II-VI QDs, only a seven-fold plasmon-induced PL enhancement is reported for Si QDs. In our paper we show that the plasmon-induced strong local PL enhancement of Si QDs in an SiN matrix can reach a 60-fold gain level. This important result was achieved on original tunable "nano-Ag/SiN(X)" plasmonic structures. In particular, we show that (i) localization of Si QDs in hot spot regions created by several randomly arranged Ag NPs and (ii) careful tuning of the multi-polar plasmon bands of Ag NPs to match resonant absorption and emission wavelengths of Si QDs, lead to the important enhancement of their PL intensity.

Electrical transport in porous silicon from improved complex impedance analysis

An improved analysis of the electrical transport parameters in meso-porous silicon is presented. Our approach is based on a separate contribution of the crystallites and their interconnections to the total impedance of meso-porous silicon layers. Meso-porous silicon morphology exhibits a columnar structure without quantum confinement. The electrical conduction is thus, partially due to the bulk conductivity within continuous paths of crystallites. The samples were realized on 0.02ω-cm p-type Si substrates. Porous silicon layers of 100µm of thickness and 50% of porosity were inserted in Al/SiO2/porous-Si/Si structures. Their electronic transport parameters were determined using complex impedance measurements. A frequency range of 102 - 107 Hz was used allowing an accurate determination of the impedance components. Combined with thermal stimulation, theses measurements provide a powerful tool for the interpretation of basic properties such as the carriers density in the crystallites and the trapping mechanisms. Our results were interpreted in terms of free carriers conduction in partially compensated crystallites prevailing at low frequencies. At high frequencies (above 10 kHz), the electrical conductivity is mainly controlled by hopping transport on localized states in the chaotic porous structure. Finally, the free carriers mobility, evaluated from SCLC measurement is discussed.

Preferential killing of cancer cells using silicon carbide quantum dots

Silicon carbide quantum dots are highly luminescent biocompatible nanoparticles whose properties might be of particular interest for biomedical applications. In this study we investigated Silicon Carbide Quantum Dots (3C-SiC QDs) cellular localisation and influence on viability and proliferation on oral squamous carcinoma (AT-84 and HSC) and immortalized cell lines (S-G). They clearly localize into the nuclei, but the presence of 3C-SiC QDs in culture medium provoke morphological changes in cultured cells. We demonstrate that 3C-SiC QDs display dose- and time-dependent selective cytotoxicity on cancer versus immortalized cells in vitro. Since one of the limitations of classical antineoplastic drugs is their lack of selectivity, these results open a new way in the search for antiproliferative drugs.