Ophthalmic drug delivery system based on the complex of gellan and ofloxacin

Complex formation between a natural polysaccharide – gellan and an antimicrobial drug – ofloxacin was studied in aqueous solution. Conductimetric and potentiometric titration curves revealed that gellan and ofloxacin forms a water-soluble complex of composition 2:1 mol/mol stabilized by ionic and hydrogen bonds. The formation of the gellan-ofloxacin complex was confirmed by FTIR spectroscopy, dynamic light scattering, zeta-potential and thermogravimetric analysis. The average hydrodynamic size of the complex was found 307±5 nm and its zetapotential was negative and equal to -15 mV. Thin films of the gellan-ofloxacin complex, gelled in 0.3 wt.% of CaCl2, were used to study the release kinetics of ofloxacin in distilled water and phosphate buffer. The drug release kinetics evaluated by UV-Vis spectroscopy at λmax = 289 nm and calculated by the Ritger-Peppas model correspond to non-Fickian diffusion in distilled water and Case II transport (zero-order kinetics) in phosphate buffer. The cumulative release of ofloxacin from the gellan-ofloxacin films was equal to 96±2% and 36±2% in phosphate buffer and distilled water, respectively. It is expected that the gellan-ofloxacin complex is able to form in situ gel on the surface of the eye and to prolong the drug residence time in the tear fluid.Peer reviewe

Harnessing photochemical internalization with dual degradable nanoparticles for combinatorial photo-chemotherapy.

Light-controlled drug delivery systems constitute an appealing means to direct and confine drug release spatiotemporally at the site of interest with high specificity. However, the utilization of light-activatable systems is hampered by the lack of suitable drug carriers that respond sharply to visible light stimuli at clinically relevant wavelengths. Here, a new class of self-assembling, photo- and pH-degradable polymers of the polyacetal family is reported, which is combined with photochemical internalization to control the intracellular trafficking and release of anticancer compounds. The polymers are synthesized by simple and scalable chemistries and exhibit remarkably low photolysis rates at tunable wavelengths over a large range of the spectrum up to the visible and near infrared regime. The combinational pH and light mediated degradation facilitates increased therapeutic potency and specificity against model cancer cell lines in vitro. Increased cell death is achieved by the synergistic activity of nanoparticle-loaded anticancer compounds and reactive oxygen species accumulation in the cytosol by simultaneous activation of porphyrin molecules and particle photolysis

Poly(2-ethyl-2-oxazoline) grafted gellan gum for potential application in transmucosal drug delivery

Gellan gum (GG) has been used to prepare polymeric carriers with prolonged retention on the eye surface for topical ocular drug delivery. In this work, GG was chemically modified with short poly(2-ethyl-2-oxazoline) (PEtOx) chains that were expected to have minimal adhesion to mucosal tissues (mucoadhesion). The choice of synthetic procedure, solvents, and reagents has been dictated by biocompatibility of the materials and possible application in drug delivery. The grafts were synthesized via cationic ring-opening polymerization and their living chains were attached onto deprotonated gellan backbone. The derivatives with three degrees of grafting were prepared by varying the in-feed mass ratio of PEtOx grafts over GG. NMR and FT-IR spectroscopies, thermogravimetric analysis, and SEC evidenced that the grafting had actually taken place. However, a greater diffusion coefficient determined for the copolymer, using diffusion-ordered spectroscopy (NMR), in relation to the diffusion of the unmodified GG, suggested either partial degradation of the backbone or a more compact structure of the copolymer. GG and its graft copolymers (GG-g-PEtOx) were found to be highly biocompatible with cells cultured under their induction at concentration of 1, 0.1 and 0.01 mg/mL demonstrated a physiological morphology, as well as an increase in viability and proliferation.Peer reviewe

High-load anaerobic co-digestion of cheese whey and liquid fraction of dairy manure in a one-stage UASB process: limits in co-substrates ratio and organic loading rate

Cheese whey is considered an important pollutant in dairy wastewaters and an environmental problem to solve. This study aimed to develop a treatment process that combines the advantages of co-digesting cheese whey with manure and the short hydraulic retention time of a high-load anaerobic treatment system by using liquid fractions of dairy manure as a co-substrate. The proposed co-digestion process consists of a one-stage UASB reactor with an external settler and effluent recycling for alkalinity supplementation. Under a constant hydraulic retention time of 2.2 days and increasing proportion of cheese whey in the feed, the system demonstrated stable operation up to a 75% cheese whey fraction in the feed, with an applied organic loading rate of 19.4 kg COD m−3 d−1, obtaining a 94.7% COD removal and a volumetric methane production rate of 6.4 m3 CH4 m−3 d−1. Critical biomass washout was experienced when the cheese whey fraction in the feed was 85%. Operation at a constant 60% cheese whey fraction in the feed mixture enabled stable operation under an organic loading rate of 28.7 kg COD m−3 d−1 and 1.3 days HRT, with 95.1% COD removal and a volumetric methane production rate of 9.5 m3 CH4 m−3 d−1. This new high-load co-digestion method proposed is a promising solution for areas where cheese factories and intensive livestock farming are responsible for environmental pollution caused by unsuitable cheese whey and manure management practices

Development of disposable carbon nanofibers electrodes supported on filters

Junta de Castilla yLeýn (GR71, BU349-U13) and the Ministerio de Economa yCompetitividad(CTQ2014-55583-R, CTQ2014-61914-EXP

Modeling lipid accumulation in oleaginous fungi in chemostat cultures. II: Validation of the chemostat model using yeast culture data from literature

A model that predicts cell growth, lipid accumulation and substrate consumption of oleaginous fungi in chemostat cultures (Meeuwse et al. in Bioproc Biosyst Eng. doi:10.1007/s00449-011-0545-8, 2011) was validated using 12 published data sets for chemostat cultures of oleaginous yeasts and one published data set for a poly-hydroxyalkanoate accumulating bacterial species. The model could describe all data sets well with only minor modifications that do not affect the key assumptions, i.e. (1) oleaginous yeasts and fungi give the highest priority to C-source utilization for maintenance, second priority to growth and third priority to lipid accumulation, and (2) oleaginous yeasts and fungi have a growth rate independent maximum specific lipid production rate. The analysis of all data showed that the maximum specific lipid production rate is in most cases very close to the specific production rate of membrane and other functional lipids for cells growing at their maximum specific growth rate. The limiting factor suggested by Ykema et al. (in Biotechnol Bioeng 34:1268–1276, 1989), i.e. the maximum glucose uptake rate, did not give good predictions of the maximum lipid production rate

Anionic polysaccharide-gellan as perspective polymer for potential application in medicine and oil recovery : a mini-review

Potential application of gellan in medicine and oil recovery based on literature survey and own results of authors has been presented in this mini-review. Purification and fractionation procedures of commercial gellan gum have been described. The application of gellan gum and its modified derivatives in medicine, in particular, as drug delivery systems accompanied by mucoadhesivity has been briefly considered. Gold nanoparticles immobilized within gellan and poly(2-ethyl-2-oxazoline)-grafted gellan have been demonstrated for photothermal treatment of Ehrlich cancer cell. Potential application of gellan in oil recovery has been considered. The prospect of organizing the gellan production in Kazakhstan has been outlined

Fabrication of tailorable pH responsive cationic amphiphilic microgels on a microfluidic device for drug release

Cationic, amphiphilic microgels of differing compositions based on hydrophilic, pH, and thermoresponsive 2-(dimethylamino)ethyl methacrylate (DMAEMA) and hydrophobic, nonionic n-butyl acrylate (BuA) are synthesized using a lab-on-a-chip device. Hydrophobic oil-in-water (o/w) droplets are generated via a microfluidic platform, with the dispersed (droplet) phase containing the DMAEMA and BuA, alongside the hydrophobic cross-linker, ethylene glycol dimethacrylate, and a free radical initiator in an organic solvent. Finally, the hydrophobic droplets are photopolymerized via a UV light source as they traverse the microfluidic channel to produce the cationic amphiphilic microgels. This platform enables the rapid, automated, and in situ production of amphiphilic microgels, which do not match the core-shell structure of conventionally prepared microgels but are instead based on random amphiphilic copolymers of DMAEMA and BuA between the hydrophobic cross-links. The microgels are characterized in terms of their swelling and encapsulation abilities, which are found to be influenced by both the pH response and the hydrophobic content of the microgels. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 59–66

Recent Advances in Nanotechnology Applied to Biosensors

In recent years there has been great progress the application of nanomaterials in biosensors. The importance of these to the fundamental development of biosensors has been recognized. In particular, nanomaterials such as gold nanoparticles, carbon nanotubes, magnetic nanoparticles and quantum dots have been being actively investigated for their applications in biosensors, which have become a new interdisciplinary frontier between biological detection and material science. Here we review some of the main advances in this field over the past few years, explore the application prospects, and discuss the issues, approaches, and challenges, with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination