Single-Walled Carbon Nanotube-Assisted Antibiotic Delivery and Imaging in S. epidermidis Strains Addressing Antibiotic Resistance

Although conventional antibiotics have evolved as a staple of modern medicine, increasing antibiotic resistance and the lack of antibiotic efficacy against new bacterial threats is becoming a major medical threat. In this work, we employ single-walled carbon nanotubes (SWCNTs) known to deliver and track therapeutics in mammalian cells via intrinsic near-infrared fluorescence as carriers enhancing antibacterial delivery of doxycycline and methicillin. SWCNTs dispersed in water by antibiotics without the use of toxic bile salt surfactants facilitate efficacy enhancement for both antibiotics against Staphylococcus epidermidis strain showing minimal sensitivity to methicillin. Doxycycline to which the strain did not show resistance in complex with SWCNTs provides only minor increase in efficacy, whereas the SWCNTs/methicillin complex yields up to 40-fold efficacy enhancement over antibiotics alone, suggesting that SWCNT-assisted delivery may circumvent antibiotic resistance in that bacterial strain. At the same time SWCNT/antibiotic formulations appear to be less toxic to mammalian cells than antibiotics alone suggesting that nanomaterial platforms may not restrict potential biomedical applications. The improvement in antibacterial performance with SWCNT delivery is tested via 3 independent assays-colony count, MIC (Minimal Inhibitory Concentration) turbidity and disk diffusion, with the statistical significance of the latter verified by ANOVA and Dunnett's method. The potential mechanism of action is attributed to SWCNT interactions with bacterial cell wall and adherence to the membrane, as substantial association of SWCNT with bacteria is observed-the near-infrared fluorescence microscopy of treated bacteria shows localization of SWCNT fluorescence in bacterial clusters, scanning electron microscopy verifies SWCNT association with bacterial surface, whereas transmission electron microscopy shows individual SWCNT penetration into bacterial cell wall. This work characterizes SWCNTs as novel advantageous antibiotic delivery/imaging agents having the potential to address antibiotic resistance.

Variation of Optical Properties of Nitrogen-doped Graphene Quantum Dots with Short/Mid/Long-wave Ultraviolet for the Development of the UV Photodetector

Nitrogen-doped graphene quantum dots (NGQDs) synthesized from a single glucosamine precursor are utilized to develop a novel UV photodetector. Optical properties of NGQDs can be altered with short- (254 nm), mid- (302 nm), and long-wave (365 nm) ultraviolet (UV) exposure leading to the reduction of absorption from deep to mid UV (200-320 nm) and enhancement above 320 nm. Significant quenching of blue and near-IR fluorescence accompanied by the dramatic increase of green/yellow emission of UV-treated NGQDs can be used as a potential UV-sensing mechanism. These emission changes are attributed to the reduction of functional groups detected by Fourier transformed infrared spectroscopy and free-radical-driven polymerization of the NGQDs increasing their average size from 4.70 to 11.20 nm at 60 min treatment. Due to strong UV absorption and sensitivity to UV irradiation, NGQDs developed in this work are utilized to fabricate UV photodetectors. Tested under long-/mid-/short-wave UV, these devices show high photoresponsivity (up to 0.59 A/W) and excellent photodetectivity (up to 1.03 × 10¹¹ Jones) with highly characteristic wavelength-dependent reproducible response. This study suggests that the optical/structural properties of NGQDs can be controllably altered via different wavelength UV treatment leading us to fabricate NGQD-based novel UV photodetectors providing high responsivity and detectivity.

Multi-Drug/Gene NASH Therapy Delivery and Selective Hyperspectral NIR Imaging Using Chirality-Sorted Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNTs) can serve as drug delivery/biological imaging agents, as they exhibit intrinsic fluorescence in the near-infrared, allowing for deeper tissue imaging while providing therapeutic transport. In this work, CoMoCAT (Cobalt Molybdenum Catalyst) SWCNTs, chirality-sorted by aqueous two-phase extraction, are utilized for the first time to deliver a drug/gene combination therapy and image each therapeutic component separately via chirality-specific SWCNT fluorescence. Each of (7,5) and (7,6) sorted SWCNTs were non-covalently loaded with their specific payload: the PI3 kinase inhibitor targeting liver fibrosis or CCR5 siRNA targeting inflammatory pathways with the goal of addressing these processes in nonalcoholic steatohepatitis (NASH), ultimately to prevent its progression to hepatocellular carcinoma. PX-866-(7,5) SWCNTs and siRNA-(7,6) SWCNTs were each imaged via characteristic SWCNT emission at 1024/1120 nm in HepG2 and HeLa cells by hyperspectral fluorescence microscopy. Wavelength-resolved imaging verified the intracellular transport of each SWCNT chirality and drug release. The therapeutic efficacy of each formulation was further demonstrated by the dose-dependent cytotoxicity of SWCNT-bound PX-866 and >90% knockdown of CCR5 expression with SWCNT/siRNA transfection. This study verifies the feasibility of utilizing chirality-sorted SWCNTs for the delivery and component-specific imaging of combination therapies, also suggesting a novel nanotherapeutic approach for addressing the progressions of NASH to hepatocellular carcinoma.

[Chronic pain in patients older than 60 years: a view of the geriatrics]

AIM

To analyze the geriatric status of patients with chronic pain.

MATERIAL AND METHODS

One hundred and sixteen patients of a geriatric unit, aged 75.66±7.98 years (110 women, 94.8%), were studied. All patients underwent general clinical examination and complex geriatric assessment, on the results of which geriatric syndromes were identified. Characteristics of pain syndrome (cause, intensity, localization) are described.

RESULTS

Chronic pain syndrome is identified in 85 (73.3%) patients. Most often pain is localized in large joints (n=44 (51.76%)) and back (n=50 (58.8%)). The intensity of pain was higher in patients with moderate dependence in daily activities compared to those with mild dependence (p<0.05). Pain intensity is associated with the degree of impairment of physical functioning (p<0.05). Patients with chronic pain have more geriatric symptoms (6.8±2.8). More syndromes (9.11±2.37) are identified in patients with marked impairment of physical functioning. The reduction of muscle strength is observed in 45.9% patients with- and 9.7% patients without chronic pain syndrome. The velocity of pace is 0.59 m/s and 0.71 m/s, respectively.

CONCLUSION

The high prevalence of chronic pain in patients of a geriatric unit is shown. The intensity of pain iss higher in patients with moderate dependence in daily activities compared to those with mild dependence. Pain intensity increases with the reduction of patient's physical functioning. Patients with chronic pain more often have dynapenia and significantly lower velocity of pace that indicates the poor outcome in elderly patients.

Safety of nonsteroidal anti-inflammatory drugs in patients with cardiovascular risk

The review presents current information on the role of NSAIDs in the development of cardiovascular disasters. The development of non-desirable cardiovascular effects and an increase in cardiovascular risk with the administration of NSAIDs, most experts assess in terms of the antagonistic effect on the platelet-vascular homeostasis of metabolites of COX-thromboxane A2 and prostaglandin I2 (prostacyclin). All the presented reviews confirming an increase in the risk of MI complications in the administration of NSAIDs, indicate the class-specificity of this undesirable effect, not homogeneous for different representatives of the group. Important clinical aspects of prescribing NSAIDs for patients with low and moderate cardiovascular risk are the clinical features of the patient and the individual set of risk factors for CVD. Such pharmacokinetic characteristics of NSAIDs as a short half-life, a high degree of binding to blood plasma albumins are indicative of greater safety of NSAIDs, but the final decision must be made based on the accumulated data of clinical trials and meta-analyzes. Keywords: nonsteroidal anti-inflammatory drugs, cardiovascular diseases, cardiovascular risk, lornoxicam, diclofenac sodium, thrombo-elastogram, myocardial infarction, stroke.

Graphene Oxide as a Multifunctional Platform for Intracellular Delivery, Imaging, and Cancer Sensing

Graphene oxide (GO), the most common derivative of graphene, is an exceptional nanomaterial that possesses multiple physical properties critical for biomedical applications. GO exhibits pH-dependent fluorescence emission in the visible/near-infrared, providing a possibility of molecular imaging and pH-sensing. It is also water soluble and has a substantial platform for functionalization, allowing for the delivery of multiple therapeutics. GO physical properties are modified to enhance cellular internalization, producing fluorescent nanoflakes with low (<15%) cytotoxicity at the imaging concentrations of 15 μg/mL. As a result, at lower flake sizes GO rapidly internalizes into HeLa cells with the following 70% fluorescence based clearance at 24 h, assessed by its characteristic emission in red/near-IR. pH-dependence of GO emission is utilized to provide the sensing of acidic extracellular environments of cancer cells. The results demonstrate diminishing green/red (550/630 nm) fluorescence intensity ratios for HeLa and MCF-7 cancer cells in comparison to HEK-293 healthy cells suggesting a potential use of GO as a non-invasive optical sensor for cancer microenvironments. The results of this work demonstrate the potential of GO as a novel multifunctional platform for therapeutic delivery, biological imaging and cancer sensing.

Modulating Chirality-Selective Photoluminescence of Single-Walled Carbon Nanotubes by Ionic Liquids

The chirality-selective near-infrared emission of surfactant-stabilized single-wall carbon nanotubes could be controlled by simply varying the anion of the commonly used 1-butyl-3-methylimidazolium ionic liquids. This result advances the notion of the designer solvent ability of ionic liquids and provides opportunities for modulating the properties of nanomaterials.

Micro-Refractometry and Local-Field Mapping with Single Molecules

The refractive index n is one of the most important materials parameters of solids and, in recent years, has become the subject of significant interdisciplinary interest, especially in nanostructures and meta-materials. It is, in principle, a macroscopic quantity, so its meaning on a length scale of a few nanometers, i.e., well below the wavelength of light, is not clear a priori and is related to methods of its measurement on this length scale. Here we introduce a novel experimental approach for mapping the effective local value [Formula: see text] of the refractive index in solid films and the analysis of related local-field enhancement effects. The approach is based on the imaging and spectroscopy of single chromophore molecules at cryogenic temperatures. Since the fluorescence lifetime T₁ of dye molecules in a transparent matrix depends on the refractive index due to the local density of the electromagnetic field (i.e., of the photon states), one can obtain the local [Formula: see text] values in the surroundings of individual chromophores simply by measuring their T₁ times. Spatial mapping of the local [Formula: see text] values is accomplished by localizing the corresponding chromophores with nanometer accuracy. We demonstrate this approach for a polycrystalline n-hexadecane film doped with terrylene. Unexpectedly large fluctuations of local-field effects and effective [Formula: see text] values (the latter between 1.1 and 1.9) were found.

Use of a glycosamine sulfate for patients with osteoarthritis and a comorbidity with high risk of the side effects from NSAIDS

The literature review is devoted to the peculiarities of treating co-morbid patients with acute conditions of chronic pain. The proved effect of NSAIDS must always correlate with the side effect risk. Patented microcrystalline glucosamine sulfate (pCGS) is likely to have an effect similar to NSAIDS because it can cause decrease of COX-2 and PGE2 gene expression. Randomized trials show, that patented microcrystalline glucosamine sulfate can impede complex structure changes and have a positive effect on the symptoms at the early stage of knee OA. Pharmacokinetic evidence demonstrates that repeated oral intake of microcrystalline glucosamine sulfate can cause the increase of GS in synovial fluid. It is necessary to monitor OA biomarkers during microcrystalline GS treatment, recommend appropriate physical exercise and study the neuropathic component of chronic pain.

Electronic edge-state and space-charge phenomena in long GaN nanowires and nanoribbons

We studied space-charge-distribution phenomena in planar GaN nanowires and nanoribbons (NRs). The results obtained at low voltages demonstrate that the electron concentration changes not only at the edges of the NR, but also in the middle part of the NR. The effect is stronger with decreasing NR width. Moreover, the spatial separation of the positive and negative charges results in electric-field patterns outside the NR. This remarkable feature of electrostatic fields outside the NR may be even stronger in 2D material structures. For larger voltages the space-charge-limited current (SCLC) effect determines the main mechanism of transport in the NR samples. The onset of the SCLC effect clearly correlates with the NR width. The results are confirmed by noise spectroscopy studies of the NR transport. We found that the noise increases with decreasing NR width and the shape of the spectra changes with voltage increase with a tendency toward slope (3/2), reflecting diffusion processes due to the SCLC effect. At higher voltages noise decreases as a result of changes in the scattering mechanisms. We suggest that the features of the electric current and noise found in the NRs are of general character and will have an impact on the development of NR-based devices.

Modifying optical properties of reduced/graphene oxide with controlled ozone and thermal treatment in aqueous suspensions

Graphene possesses a number of advantageous properties, however, does not exhibit optical emission, which limits its use in optoelectronics. Unlike graphene, its functional derivative, graphene oxide (GO) exhibits fluorescence emission throughout the visible. Here, we focus on controlled methods for tuning the optical properties of GO. We introduce ozone treatment of reduced graphene oxide (RGO) in order to controllably transform it from non-emissive graphene-like material into GO with a specific fluorescence emission response. Solution-based treatment of RGO for 5-45 min with ∼1.2 g l^-1 ozone/oxygen gas mixture yields a drastic color change, bleaching of the absorption in the visible and the stepwise increase in fluorescence intensity and lifetime. This is attributed to the introduction of oxygen-containing functional groups to RGO graphitic platform as detected by the infrared spectroscopy. A reverse process: controllable quenching of this fluorescence is achieved by the thermal treatment of GO in aqueous suspension up to 90 °C. This methodology allows for the wide range alteration of GO optical properties starting from the dark-colored non-emissive RGO material up to nearly transparent highly ozone-oxidized GO showing substantial fluorescence emission. The size of the GO flakes is concomitantly altered by oxidation-induced scission. Semi-empirical PM3 theoretical calculations on HyperChem models are utilized to explore the origins of optical response from GO. Two models are considered, attributing the induced emission either to the localized states produced by oxygen-containing addends or the islands of graphitic carbon enclosed by such addends. Band gap values calculated from the models are in the agreement with experimentally observed transition peak maxima. The controllable variation of GO optical properties in aqueous suspension by ozone and thermal treatments shown in this work provides a route to tune its optical response for particular optoelectronics or biomedical applications.

Looking at a blinking quantum emitter through time slots: the effect of blind times

Most experimental observations of physical processes are naturally accompanied by "blind" ("dead") times, which in principle can distort the result of measurements. Here we analyze how the presence of blind times in measurements changes the measured statistics of blinking fluorescence of single quantum dots. We show that information can be extracted even for blinking processes with characteristic times longer than both blind times and time slots between them.

[Current possibilities of correcting subchondral bone resorption as a major pathogenetic factor for progressive osteoarthrosis]

The paper considers the current pathogenesis, by choosing the actual targets of pharmacotherapy with available drugs. It reflects the cytokine mechanisms responsible for lesion of the synovial membranes, cartilage, and subchondral bone. Particular emphasis is laid on the role of chondroitin sulfate, glucosamine, vitamin D3 as drugs that affect the key components of pathogenesis, including the volume of resorptive cavities in the subchondral bone.

Measuring single-walled carbon nanotube length distributions from diffusional trajectories

A new method is demonstrated for measuring the length distributions of dispersed single-walled carbon nanotube (SWCNT) samples by analyzing diffusional motions of many individual nanotubes in parallel. In this method, termed "length analysis by nanotube diffusion" (LAND), video sequences of near-IR fluorescence microscope images showing many semiconducting SWCNTs are recorded and processed by custom image analysis software. This processing locates the individual nanotubes, tracks their translational trajectories, computes the corresponding diffusion coefficients, and converts those values to nanotube lengths. The deduced length values are then compiled into a histogram of lengths present in the sample. By using specific excitation wavelengths and emission filters, this analysis is performed on selected (n,m) structural species. The new LAND method has been found to give distributions in very good agreement with those obtained by conventional AFM analysis of the same samples. Because it is fluorescence-based, LAND monitors only semiconducting, relatively pristine SWCNTs. However, it is less sensitive to artifacts from impurities and bundled nanotubes than AFM or light scattering methods. In addition, samples can be analyzed with less time and operator attention than by AFM. LAND is a promising alternative method for characterizing length distributions of SWCNTs in liquid suspension.

Analyzing absorption backgrounds in single-walled carbon nanotube spectra

The sources of broad backgrounds in visible-near-IR absorption spectra of single-walled carbon nanotube (SWCNT) dispersions are studied through a series of controlled experiments. Chemical functionalization of nanotube sidewalls generates background absorption while broadening and red-shifting the resonant transitions. Extensive ultrasonic agitation induces a similar background component that may reflect unintended chemical changes to the SWCNTs. No major differences are found between spectral backgrounds in sample fractions with average lengths between 120 and 650 nm. Broad background absorption from amorphous carbon is observed and quantified. Overlapping resonant absorption bands lead to elevated backgrounds from spectral congestion in samples containing many SWCNT structural species. A spectral modeling method is described for separating the background contributions from spectral congestion and other sources. Nanotube aggregation increases congestion backgrounds by broadening the resonant peaks. Essentially no background is seen in sorted pristine samples enriched in a single semiconducting (n,m) species. By contrast, samples enriched in mixed metallic SWCNTs show broad intrinsic absorption backgrounds far from the resonant transitions. The shape of this metallic background component and its absorptivity coefficient are quantitatively assessed. The results obtained here suggest procedures for preparing SWCNT dispersions with minimal extrinsic background absorptions and for quantifying the remaining intrinsic components. These findings should allow improved characterization of SWCNT samples by absorption spectroscopy.

[Osteoarthritis and cardiovascular diseases in elderly patients: clinical and pathogenetic interrelationship]

Osteoarthritis (OA) is one of the most common medical conditions in elderly people. This article presents the survey data on a problem of poly-morbidities (co-morbidities) at osteoarthritis. Special attention is paid to a combination of osteoarthritis with cardiovascular pathology, and also the data testifying the association between osteoarthritis and the increased death rate from cardiovascular pathology. On the basis of the literature data analysis a hypothesis about an etiopathogenic interrelation between osteoarthritis and cardiovascular pathology is presented. According to the authors, potential pathogenetic links include a chronic nonspecific inflammation and metabolic infringements. There are also evidences that vascular pathology may initiate and/or worsen the disease progression. The important factors aggravating a current cardiovascular disease in patients with osteoarthritis are: the restriction of physical activities and irrational pharmacotherapy of osteoarthritis clinical symptoms (increased risk of cardiovascular accidents is considered as a class-specific side-effect for all NSAIDs). The authors present the own data on rational pharmacotherapy of patients with osteoarthritis and somatic pathology by means of SYSADOA influencing the disease symptoms and being able to modify structural changes (glucosamine, chondroitine sulphate - ARTRA).

Quantifying the semiconducting fraction in single-walled carbon nanotube samples through comparative atomic force and photoluminescence microscopies

A new method was used to measure the fraction of semiconducting nanotubes in various as-grown or processed single-walled carbon nanotube (SWCNT) samples. SWCNT number densities were compared in images from near-IR photoluminescence (semiconducting species) and AFM (all species) to compute the semiconducting fraction. The results show large variations among growth methods and effective sorting by density gradient ultracentrifugation. This counting-based method provides important information about SWCNT sample compositions that can guide controlled growth methods and help calibrate bulk characterization techniques.

[Toxicological evaluation of chronic exposure to dinil]

Experiments on rats were carried out to study the effect of dinil on the animals on chronic intake of the agent in the quantities exceeding the maximum permissible concentrations by many times. Despite few biochemical changes, there was a certain tension of adaptive processes, which appeared as a change mainly in the integral characteristics of the plasma amino acid pool. The observed changes in the levels of neurotransmitters and neuroactive amino acids in the striatum, midbrain, and hypothalamus are characterized by specific characteristics and may underlie the negative effect of dinil on central nervous system functions. Long-term administration of the agent to the animals did not induce pronounced morphological and biochemical disturbances in the tissues of the liver, heart, and kidneys. Changes in the concentrations of serotonin and neuroactive amine acids in the brain regions might have the greatest consequences to the body. Since the detectable changes in a number of metabolites are likely to be functional in the given period (monthly dinil use), an attempt to correct developing disorders with metabolic therapy agents may be recommended.

Participation of oxygen in the bacterial transformation of 2,4,6-trinitrotoluene

The exposure of Bacillus cereus ZS18 cell suspensions to 2,4,6-trinitrotoluene (TNT) in the absence of other oxidizable substrates increases oxygen uptake, exceeding the basal level of respiration of the bacterium 1.5- and 2-fold with 50 and 100 mg/liter of TNT, respectively. The interaction of both living and to less extent dead bacterial cells with TNT results in the accumulation of superoxide anion (O2*-) in the extracellular medium, which was revealed by the EPR spectroscopy. The accumulation of O2*- decreased by 50-70% in the presence of Cu,Zn-superoxide dismutase of animal origin. In the presence of living bacterial cells, the level of TNT decreased progressively, yielding hydroxylaminodinitrotoluenes together with O2*-. In the presence of heat-killed cells, a moderate decrease in TNT was observed, and the appearance of O2*- was not accompanied by the production of any detectable TNT metabolites. Chelating agents inhibited the transformation of TNT and decreased the formation of O2*-. The demonstrated generation of O2*- during the interaction of TNT with K4[Fe(CN)6] together with the observed effects of chelating agents suggest the participation of iron in the one-electron reduction of TNT and the functioning of an extracellular redox cycle with the involvement of molecular oxygen.

Electric field quenching of carbon nanotube photoluminescence

The effect of external electric fields on the photoluminescence intensity of single-walled carbon nanotubes was investigated for individual nanotubes and bulk samples in polymeric films. Fields of up to 10(7) V/m caused dramatic, reversible decreases in emission intensity. Quenching efficiency varied as the cosine of the angle between the field and nanotube axis and decreased with increasing optical band gap. Photoluminescence intensity was found to follow a reciprocal hyperbolic cosine dependence on electric field.