Search Results (6)

Glaucoma therapy aims at lowering intra-ocular pressure (IOP). Brinzolamide, a carbonic anhydrase inhibitor, is utilized as a second-line medication for treating ocular hypertension and primary open-angle glaucoma (POAG). The drug lowers the IOP making it a therapeutic agent against glaucoma, and due to its poor water solubility, is commercially available as Azopt^®, a 1% ophthalmic suspension. Adverse effects such as blurred vision, ocular irritation, discomfort, and bitter taste are associated with the use of the marketed brinzolamide formulation. This study aims to test the feasibility of formulating and in vitro testing of brinzolamide-PLGA nanoparticles for improved toxicity profile. The nanoparticles were prepared by the oil-in-water (O/W) emulsion-solvent evaporation method. Particle size and zeta potential were determined by dynamic light scattering (DLS). The morphology of the nanoparticles was determined by scanning electron microscopy (SEM). Encapsulation of the drug was verified by high-performance liquid chromatography (HPLC) and the compatibility of the polymer and drug was verified by Fourier transform infrared (FTIR) spectroscopy. The in vitro drug release profile was assessed employing the dialysis method. Intracellular localization of the nanoparticles was assessed by confocal microscopy utilizing Rhodamine 123-loaded nanoparticles. Cytotoxicity of the formulation was assessed on Statens Seruminstitut Rabbit Cornea (SIRC) and transfected Human Corneal Epithelial (SV40 HCEC) cell lines. The particle size of the nanoparticle formulations ranged from 202.3 ± 2.9 nm to 483.1 ± 27.9 nm for blank nanoparticles, and 129.6 ± 1.5 nm to 350.9 ± 8.5 nm for drug-loaded nanoparticles. The polydispersity of the formulations ranged from 0.071 ± 0.032 to 0.247 ± 0.043 for blank nanoparticles, and 0.089 ± 0.028 to 0.158 ± 0.004 for drug-loaded nanoparticles. Drug loading and encapsulation efficiencies ranged from 7.42–15.84% and 38.93–74.18%, respectively. The in vitro drug release profile for the optimized formulation was biphasic, with a ~54% burst release for the initial 3 h, followed by a cumulative 85% and 99% released at 24 and 65 h, respectively. Uptake study showed nanoparticles(NPs) localization in the cytoplasm and around the nuclei of the cells. Brinzolamide-PLGA nanoparticles were successfully developed, characterized, and tested in vitro. Preliminary data show intracellular localization of the nanoparticles in the cytoplasm of SIRC and SV40 HCEC cells. The formulations appeared to be relatively non-cytotoxic to the cells. The research data from the study provided preliminary data for successful development and promising in vitro absorption efficacy for brinzolamide-loaded PLGA nanoparticle formulation. Full article

This paper presents a low-voltage CMOS four-stage amplifier operating in the subthreshold region. The first design technique includes the cross-feedforward positive feedback frequency compensation (CFPFC) for obtaining better bandwidth efficiency in a low-voltage multi-stage amplifier. The second design technique incorporates both the bulk-drain-driven input stage topology in conjunction with a low-voltage attenuator to permit operation at a low voltage, and improves the input common-mode range (ICMR). The proposed circuit is implemented using TSMC-40 nm process technology. It consumes 0.866 μW at a supply voltage of 0.5 V. With a capacitive load of 50 pF, this four-stage amplifier can achieve 84.59 dB in gain, 161.00 kHz in unity-gain bandwidth, 96 deg in phase margin, and 5.7 dB in gain margin whilst offering an input-referred noise of 213.63 $\mathrm{n}\mathrm{V}/\sqrt{\mathrm{H}\mathrm{z}}$ @1 kHz, small-signal power-bandwidth FoM_ss of 9.31 (MHz∙pF/μW), and noise-power per bandwidth-based FoM_npb of 1.15 × 10⁻⁶ (($\mathrm{\mu }\mathrm{V}/\sqrt{\mathrm{H}\mathrm{z}}$)·µW/Hz). Compared to the conventional bulk-driven input stage design technique, it offers improved multi-parameter performance metrics in terms of noise, power, and bandwidth at a compromising tradeoff on ICMR with respect to bulk-driven amplifier design. Compared with conventional gate-source input stage design, it offers improved ICMR. The amplifier is useful for low-voltage analog signal-processing applications. Full article

Supported Pd/CeO₂ catalytic systems have been widely investigated in the low-temperature oxidation of CO (LTO CO) due to the unique oxygen storage capacity and redox properties of the ceria support, which highly influence the structural, chemical and electronic state of Pd species. Herein, operando near-ambient pressure XPS (NAP-XPS) technique has allowed the study of a conventional Pd/CeO₂ catalyst surface during the CO oxidation reaction under experimental conditions closer to the actual catalytic reaction, unfeasible with other surface science techniques that demand UHV conditions. SEM, HRTEM and XRD analyses of the powder catalyst, prepared by conventional incipient wetness impregnation, reveal uniformly CeO₂-loaded Pd NPs of less than 2 nm size, which generated an increase in oxygen vacancies with concomitant ceria reduction, as indicated by H₂-TPR and Raman measurements. Adsorbed peroxide (O₂²⁻) species on the catalyst surface could also be detected by Raman spectra. Operando NAP-XPS results obtained at the ALBA Synchrotron Light Source revealed two kinds of Pd species under reaction conditions, namely PdO_x and Pd^II ions in a Pd_xCe_1−xO_2−δ solution, the latter one appearing to be crucial for the CO oxidation. By means of a non-destructive depth profile analysis using variable synchrotron excitation energies, the location and the role of these palladium species in the CO oxidation reaction could be clarified: PdO_x was found to prevail on the upper surface layers of the metallic Pd supported NPs under CO, while under reaction mixture it was rapidly depleted from the surface, leaving a greater amount in the subsurface layers (7% vs. 12%, respectively). On the contrary, the Pd_xCe_1−xO_2−δ phase, which was created at the Pd–CeO₂ interface in contact with the gas environment, appeared to be predominant on the surface of the catalyst. Its presence was crucial for CO oxidation evolution, acting as a route through which active oxygen species could be transferred from ceria to Pd species for CO oxidation. Full article

Plastics pervade our environment and potentially release important quantities of plastic nanoparticles (NPs) from degradation in the environment. The purpose of this study was to examine the crowding effects of polystyrene NPs on lactate dehydrogenase (LDH) in vitro and following exposure to Hydra attenuata. First, LDH activity was measured in vitro in the presence of filamentous (F-)actin and NPs (50 and 100 nm diameter) to determine changes in viscosity and the fractal kinetics of LDH. The fractal dimension (fD) was also determined using the rescaled range analysis procedure. Secondly, these changes were examined in hydra exposed to NPs for 96h to concentrations of NPs. The data revealed that the addition of F-actin increased the rate of LDH at low substrate (pyruvate) concentrations compared to LDH alone with a gradual decrease in the rate with the addition of pyruvate, which is characteristic of the fractal behavior of enzymes in crowded environments. The addition of 50 and 100 nm NPs also produced these changes, which suggest that NPs could change the space properties of the LDH reaction. The fD was reduced to 0.85 and 0.91 with 50 and 100 nm NPs compared to 1.093 with LDH alone. Decrease in the fD was related with increased amplitudes and frequency in viscosity waves in the reaction media. Exposure of hydra to NPs confirmed the increase in LDH activity and the fD was significantly correlated with LDH activity (r = −0.5). Correction of LDH activity (residuals) still revealed an increase in LDH activity in hydra suggesting increased anaerobic metabolism by NPs. In conclusion, the presence of NPs in the intracellular space decreased the fD, which could influence LDH activity in organisms exposed to NPs. Full article

Continuous wet chemical approaches for the production of inorganic nanoparticles are important for large scale production of nanoparticles. Here we describe a bottom-up, wet chemical method applying a microjet reactor. This technique allows the separation between nucleation and growth in a continuous reactor environment. Zinc oxide (ZnO), magnetite (Fe₃O₄), as well as brushite (CaHPO₄·2H₂O), particles with a small particle size distribution can be obtained continuously by using the rapid mixing of two precursor solutions and the fast removal of the nuclei from the reaction environment. The final particles were characterized by FT-IR, TGA, DLS, XRD and SEM techniques. Systematic studies on the influence of the different process parameters, such as flow rate and process temperature, show that the particle size can be influenced. Zinc oxide was obtained with particle sizes between 44 nm and 102 nm. The obtained magnetite particles have particle sizes in the range of 46 nm to 132 nm. Brushite behaves differently; the obtained particles were shaped like small plates with edge lengths between 100 nm and 500 nm. Full article

We present the first computational study of the effects of isotopic substitution on the operation of dye-sensitized solar cells. Ab initio molecular dynamics is used to study the effect of deuteration on light absorption, dye adsorption dynamics, the averaged over vibrations driving force to injection (∆G_i) and regeneration (∆G_r), as well as on promotion of electron back-donation in dyes NK1 (2E,4E-2-cyano-5-(4-dimethylaminophenyl)penta-2,4-dienoic acid) and NK7 (2E,4E-2-cyano-5-(4-diphenylaminophenyl)penta-2,4-dienoic acid) adsorbed in monodentate molecular and bidentate bridging dissociative configurations on the anatase (101) surface of TiO₂. Deuteration causes a red shift of the absorption spectrum of the dye/TiO₂ complex by about 5% (dozens of nm), which can noticeably affect the overlap with the solar spectrum in real cells. The dynamics effect on the driving force to injection and recombination (the difference between the averaged <∆G_i,r> and ∆G_i,r^equil at the equilibrium configuration) is strong, yet there is surprisingly little isotopic effect: the average driving force to injection <∆G_i> and to regeneration <∆G_r> changes by only about 10 meV upon deuteration. The nuclear dynamics enhance recombination to the dye ground state due to the approach of the electron-donating group to TiO₂, yet this effect is similar for deuterated and non-deuterated dyes. We conclude that the nuclear dynamics of the C-H(D) bonds, mostly affected by deuteration, might not be important for the operation of photoelectrochemical cells based on organic dyes. As the expectation value of the ground state energy is higher than its optimum geometry value (by up to 0.1 eV in the present case), nuclear motions will affect dye regeneration by recently proposed redox shuttle-dye combinations operating at low driving forces. Full article