A green chemistry approach towards synthesizing hydrogel for sustained ocular delivery of brinzolamide: In vitro and ex vivo evaluation

Brinzolamide is a carbonic anhydrase inhibitor used in the eye drop form for the treatment of glaucoma. It requires frequent dosing to attain therapeutic concentration. Therefore, this study aimed to prepare sustained ocular drug delivery of brinzolamide. The objective of the study was to prepare a hydrogel loaded with a nanostructured lipid carrier (NLC) of brinzolamide. The hydrogel was prepared by a green synthesis approach using genipin as a natural crosslinking agent and polymers such as carboxymethyl chitosan and poloxamer 407. The melt emulsification-ultra sonication method was used to prepare a nanostructured lipid carrier of brinzolamide, which was loaded into a hydrogel using a swelling and loading method. The NLC formulation has shown small particle sizes of 111.20 ?± ?2.15 ?nm, polydispersity index of 0.280 ?± ?0.005 and % entrapment efficiency of 82.16% ?± ?0.14%. The NLC-loaded hydrogels of brinzolamide formulations were studied for swelling properties and showed temperature and pH-responsive swelling behavior. The optimized hydrogel formulation has been studied for in vitro drug release and showed drug release for a longer duration (24 ?h) than marketed eye drops (8 ?h). In an ex vivo study, hydrogel formulations showed transcorneal permeability 4.54 times greater than marketed eye drops. The hydrogel formulation of brinzolamide produced by the green synthesis method has shown sustained-release properties with no sign of ocular irritation. Hence, the hydrogel of brinzolamide-loaded NLC would be the potential drug delivery approach in the near future for sustained ocular drug delivery in glaucoma management.     

Partially carbonized tungsten oxide as electrode material for asymmetric supercapacitors

Journal of Solid State Electrochemistry - Synthesis of partially carbonized tungsten oxide employing a simple, one-step, and scalable in-situ reduction/carbonization process is reported along with...     

The single-mode rate equations for semiconductor lasers with thermal effects

A mathematical model describing the coupling of electrical,optical and thermal effects in semiconductor lasers is introduced.Numerical and asymptotic solutions are derived, including expressionsfor key physical quantities such as the initial time delay,the frequency of spike oscillation and the temperature rise,together with its influence on the photon density, the electronconcentration and the threshold current. The consequences ofthermal effects in reducing efficiency are thus quantified.     

Improved models for the phase behaviour of hydrogen fluoride: chain and ring aggregates in the SAFT approach and the AEOS model

Hydrogen fluoride presents one of the strongest hydrogen bonds known. Ring aggregates exist both in the vapour and liquid phases at low temperatures resulting in an anomalously high low-temperature vapour pressure. The effect of ring-like aggregates on the vapour—liquid phase equilibria of associating fluids is studied within the framework of the statistical associating fluid theory (SAFT) and in the chemical model of Lencka and Anderko (AEOS). The SAFT approach incorporates separate contributions to describe chain formation, association (hydrogen bonding), and long range dispersion forces. The treatment of the association interactions stems from the thermodynamic perturbation theory of Wertheim. At the first level of approximation the contribution of ring-like aggregates is neglected and only chain- and treelike structures are treated. In this work an earlier extension of the approach to incorporate ring aggregates is used to model the phase behaviour of hydrogen fluoride. The chemical model of Lencka and Anderko for associating fluids is also considered together with a modification that takes into account the formation of ring aggregates. Vapour pressures and coexistence densities are examined together with heats of vapourization, and the calculations are compared with experimental data.     

Electron spin resonance studies of 199HgH, 201HgH, 199HgD and 201HgD isolated in neon and argon matrices at 4K: an electronic structure investigation

Various isotopomers of the mercury hydride radical (HgH) have been generated in a microwave discharge and trapped in neon and argon matrices at 4 K for electron spin resonance (ESR) investigations. Both the dipolar (A_dip) and isotropic (A_iso) components of the nuclear hyperfine interactions have been directly measured for ¹⁹⁹Hg, ²⁰¹Hg, H and D. Electronic structure information for HgH in its X²Σ ground state obtained from the hyperfine data is compared with theoretical results from several different computational methods. The hyperfine interactions in HgH are unusually large with A_iso(¹⁹⁹Hg) = 6859(3), A_dip(¹⁹⁹Hg) = 446(3), A_iso(H) = 730(2) and A_dip(H) = 0(2) MHz. A standard analysis of the hyperfine interactions demonstrates the need for a more in-depth theoretical treatment of HgH that should include relativistic effects. An interesting shift in spin density is observed when deuterium replaces hydrogen in HgH. The decreased spin density on deuterium, which was demonstrated in earlier studies, can now be more fully investigated since these new measurements confirm an associated increase in spin density on mercury     

The Saffman-Taylor problem for an extremely shear-thinning fluid

We consider a steady flow driven by pushing a finger of gasinto a highly shear-thinning power-law fluid, with exponentn, in a Hele-Shaw channel. We formulate the problem in termsof the streamfunction , which satisfies the p-Laplacian equation (with ), and investigate travelling wave solutions in the large-n (extreme shear-thinning) limit.We take a Legendre transform of the free-boundary problem for, which reduces it to a linear problem on a fixed domain. The solution to this problem is foundby using matched asymptotic expansions and the resulting shapeof the finger deduced (being, to leading order, a semi-infinitestrip). The nonlinear problem for the streamfunction is alsotreated using matched asymptotic expansion in the physical plane.The finger-width selection problem is briefly discussed in termsof our results.     

At a glance: cellular biology for engineers

Engineering contributions have played an important role in the rise and evolution of cellular biology. Engineering technologies have helped biologists to explore the living organisms at cellular and molecular levels, and have created new opportunities to tackle the unsolved biological problems. There is now a growing demand to further expand the role of engineering in cellular biology research. For an engineer to play an effective role in cellular biology, the first essential step is to understand the cells and their components. However, the stumbling block of this step is to comprehend the information given in the cellular biology literature because it best suits the readers with a biological background. This paper aims to overcome this bottleneck by describing the human cell components as micro-plants that form cells as micro-bio-factories. This concept can accelerate the engineers' comprehension of the subject. In this paper, first the structure and function of different cell components are described. In addition, the engineering attempts to mimic various cell components through numerical modelling or physical implementation are highlighted. Next, the interaction of different cell components that facilitate complicated chemical processes, such as energy generation and protein synthesis, are described. These complex interactions are translated into simple flow diagrams, generally used by engineers to represent multi-component processes.     

Application of Vitamin E TPGS in ocular therapeutics – Attributes beyond excipient

Diseases affecting the anterior segment and the external surface of the eye are usually treated by drugs applied topically. The formulations designed for this purpose are developed to deliver active pharmaceutical agents to the eye optimally. These formulations are prepared by adding various agents (excipients) that help to maintain stability of the formulation, prevent microbial contamination, and allow easy administration with adequate drug bioavailability with the minimum ocular irritation and toxic effects at the administration site. The excipients do not have their own pharmacological actions, but Vitamin E TPGS (d-α-Tocopheryl polyethylene glycol 1000 succinate) seems to break this notion. Besides having drug formulation enhancement properties, it also possesses antioxidant properties, which have been found to have a beneficial effect on various ophthalmological diseases such as age-related macular degeneration, uveitis, glaucoma, and cataract. In this review, we primarily focus on the properties and applications of Vitamin E TPGS in ocular drug delivery and the benefits of Vitamin E (Vit E) in numerous sight-threatening ailments of the rear and front segment of the eye. Additionally, p-glycoprotein inhibition and the anti-cancer potential of vitamin E TPGS have also been summarized.