Lead release kinetics and film transformation of Pb-MnO2 pre-coated anode in long-term zinc electrowinning

It was previously shown that polycaprolactone (PCL)-based electrospun-produced paclitaxel (PTX)-enriched matrices exhibit long-term drug release kinetics and can be used as coatings for drug-eluting stents (DES). The installation of vascular stents involves a twofold increase in stent diameter and, therefore, an elongation of the matrices covering the stents, as well as the arterial wall in a stented area. We studied the influence of matrix elongation on its structure and PTX release using three different electrospun-produced matrices. The data obtained demonstrate that matrix elongation during stent installation does not lead to fiber breaks and does not interfere with the kinetics of PTX release. To study PTX diffusion through the expanded artery wall, stents coated with 5%PCL/10%HSA/3%DMSO/PTX and containing tritium-labeled PTX were installed into the freshly obtained iliac artery of a rabbit. The PTX passing through the artery wall was quantified using a scintillator β-counter. The artery retained the PTX and decreased its release from the coating. The retention of PTX by the arterial wall was more efficient when incubated in blood plasma in comparison with PBS. The retention/accumulation of PTX by the arterial wall provides a prolonged drug release and allows for the reduction in the dose of the drugs in electrospun-produced stent coatings.

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Engineering microenvironment of biodegradable polyester systems for drug stability and release control

Therapeutic Delivery ◽

10.4155/tde-2020-0113 ◽

2021 ◽

Author(s):

Nisar Ul Khaliq ◽

Dhawal Chobisa ◽

Coralie A Richard ◽

Monica R Swinney ◽

Yoon Yeo

Keyword(s):

Lactic Acid ◽

Glycolic Acid ◽

Release Kinetics ◽

Drug Stability ◽

Poly Lactic Acid ◽

Polymeric Systems ◽

Us Fda ◽

History Of Use ◽

Release Control

Polymeric systems made of poly(lactic acid) or poly(lactic-co-glycolic acid) are widely used for long-term delivery of small and large molecules. The advantages of poly(lactic acid)/poly(lactic-co-glycolic acid) systems include biodegradability, safety and a long history of use in US FDA-approved products. However, as drugs delivered by the polymeric systems and their applications become more diverse, the significance of microenvironment change of degrading systems on long-term drug stability and release kinetics has gained renewed attention. In this review, we discuss various issues experienced with acidifying microenvironment of biodegradable polymer systems and approaches to overcome the detrimental effects of polymer degradation on drug stability and release control.

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Controlling methacryloyl substitution of chondroitin sulfate: injectable hydrogels with tunable long-term drug release profiles

Journal of Materials Chemistry B ◽

10.1039/c8tb03020k ◽

2019 ◽

Vol 7 (13) ◽

pp. 2151-2161 ◽

Cited By ~ 14

Author(s):

Kimberly J. Ornell ◽

Danilo Lozada ◽

Nhi V. Phan ◽

Jeannine M. Coburn

Keyword(s):

Drug Release ◽

Chondroitin Sulfate ◽

Release Kinetics ◽

Injectable Hydrogels ◽

Drug Release Kinetics ◽

Release Profiles

Controlling the degree of methacryloyl substitution on chondroitin sulfate allows for tunable drug release kinetics.

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Controlled and Local Delivery of Antibiotics by 3D Core/Shell Printed Hydrogel Scaffolds to Treat Soft Tissue Infections

Pharmaceutics ◽

10.3390/pharmaceutics13122151 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2151

Author(s):

Ashwini Rahul Akkineni ◽

Janina Spangenberg ◽

Michael Geissler ◽

Saskia Reichelt ◽

Hubert Buechner ◽

...

Keyword(s):

Soft Tissue ◽

Antimicrobial Agents ◽

Release Kinetics ◽

Core Shell ◽

Burst Release ◽

High Morbidity ◽

Local Concentration ◽

Soft Tissue Infections ◽

Antibiotic Delivery

Soft tissue infections in open fractures or burns are major cause for high morbidity in trauma patients. Sustained, long-term and localized delivery of antimicrobial agents is needed for early eradication of these infections. Traditional (topical or systemic) antibiotic delivery methods are associated with a variety of problems, including their long-term unavailability and possible low local concentration. Novel approaches for antibiotic delivery via wound coverage/healing scaffolds are constantly being developed. Many of these approaches are associated with burst release and thus seldom maintain long-term inhibitory concentrations. Using 3D core/shell extrusion printing, scaffolds consisting of antibiotic depot (in the core composed of low concentrated biomaterial ink 3% alginate) surrounded by a denser biomaterial ink (shell) were fabricated. Denser biomaterial ink (composed of alginate and methylcellulose or alginate, methylcellulose and Laponite) retained scaffold shape and modulated antibiotic release kinetics. Release of antibiotics was observed over seven days, indicating sustained release characteristics and maintenance of potency. Inclusion of Laponite in shell, significantly reduced burst release of antibiotics. Additionally, the effect of shell thickness on release kinetics was demonstrated. Amalgamation of such a modular delivery system with other biofabrication methods could potentially open new strategies to simultaneously treat soft tissue infections and aid wound regeneration.

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Electrospun poly (L-lactic acid)/gelatin membranes loaded with doxorubicin for effective suppression of glioblastoma cell growth in vitro and in vivo

Regenerative Biomaterials ◽

10.1093/rb/rbab043 ◽

2021 ◽

Author(s):

Boxun Liu ◽

Zhizhong Jin ◽

Haiyan Chen ◽

Lun Liang ◽

Yao Li ◽

...

Keyword(s):

Drug Delivery ◽

Lactic Acid ◽

Release Kinetics ◽

Drug Loading ◽

Composite Membranes ◽

Spectroscopic Techniques ◽

Loading Process

Abstract Electrospun membranes are attracting interest as a drug delivery system because of their material composition flexibility and versatile drug loading. In this study, the electrospun membrane was loaded with doxorubicin (DOX) via electrostatic adsorption for long-term drug delivery. DOX loading process was optimized by varying temperature, time, drug concentration, pH, and ionic strength of solutions. The loading process did not impair the structural properties of the membrane. Next, we investigated the drug release kinetics using spectroscopic techniques. The composite membranes released 22% of the adsorbed DOX over the first 48 h, followed by a slower and sustained release over 4 weeks. The DOX release was sensitive to acidic solutions that the release rate at pH 6.0 was 1.27 times as that at pH 7.4. The DOX-loaded membranes were found to be cytotoxic to U-87 MG cells in vitro that decreased the cell viability from 82.92% to 25.49% from 24 h to 72 h of co-incubation. These membranes showed strong efficacy in suppressing tumour growth in vivo in glioblastoma-bearing mice that decreased the tumour volume by 77.33% compared to blank membrane-treated group on Day 20. In conclusion, we have developed an effective approach to load DOX within a clinically-approved poly (L-lactic acid)/gelatin membrane for local and long-term delivery of DOX for the treatment of glioblastoma.

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Developmental Time Course of SNAP-25 Isoforms Regulate Hippocampal Long-Term Synaptic Plasticity and Hippocampus-Dependent Learning

International Journal of Molecular Sciences ◽

10.3390/ijms21041448 ◽

2020 ◽

Vol 21 (4) ◽

pp. 1448

Author(s):

Katisha R. Gopaul ◽

Muhammad Irfan ◽

Omid Miry ◽

Linnea R. Vose ◽

Alexander Moghadam ◽

...

Keyword(s):

Synaptic Plasticity ◽

Time Course ◽

Splice Variants ◽

Developmental Regulation ◽

Release Kinetics ◽

Long Term Potentiation ◽

Developmental Time ◽

Compensatory Mechanisms ◽

Schaffer Collateral

SNAP-25 is essential to activity-dependent vesicle fusion and neurotransmitter release in the nervous system. During early development and adulthood, SNAP-25 appears to have differential influences on short- and long-term synaptic plasticity. The involvement of SNAP-25 in these processes may be different at hippocampal and neocortical synapses because of the presence of two different splice variants, which are developmentally regulated. We show here that the isoform SNAP-25a, which is expressed first developmentally in rodent brain, contributes to developmental regulation of the expression of both long-term depression (LTD) and long-term potentiation (LTP) at Schaffer collateral-CA1 synapses in the hippocampus. In one month old mice lacking the developmentally later expressed isoform SNAP-25b, Schaffer collateral-CA1 synapses showed faster release kinetics, decreased LTP and enhanced LTD. By four months of age, SNAP-25b-deficient mice appeared to have compensated for the lack of the adult SNAP-25b isoform, now exhibiting larger LTP and no differences in LTD compared to wild type mice. Interestingly, learning a hippocampus-dependent task reversed the reductions in LTP, but not LTD, seen at one month of age. In four month old adult mice, learning prevented the compensatory up-regulation of LTD that we observed prior to training. These findings support the hypothesis that SNAP-25b promotes stronger LTP and weakens LTD at Schaffer collateral-CA1 synapses in young mice, and suggest that compensatory mechanisms can reverse alterations in synaptic plasticity associated with a lack of SNAP-25b, once mice reach adulthood.

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Long-Term Depression of Synaptic Inhibition Is Expressed Postsynaptically in the Developing Auditory System

Journal of Neurophysiology ◽

10.1152/jn.00386.2003 ◽

2003 ◽

Vol 90 (3) ◽

pp. 1479-1488 ◽

Cited By ~ 40

Author(s):

Eric H. Chang ◽

Vibhakar C. Kotak ◽

Dan H. Sanes

Keyword(s):

Release Kinetics ◽

Mean Amplitude ◽

Ruthenium Red ◽

Synapse Elimination ◽

Long Term Depression ◽

Medial Nucleus ◽

Auditory Brain Stem ◽

Pulse Ratio ◽

Activity Dependent

Inhibitory transmission is critically involved in the functional maturation of neural circuits within the brain. However, the mechanisms involved in its plasticity and development remain poorly understood. At an inhibitory synapse of the developing auditory brain stem, we used whole cell recordings to determine the site of induction and expression of long-term depression (LTD), a robust activity-dependent phenomenon that decreases inhibitory synaptic gain and is postulated to underlie synapse elimination. Recordings were obtained from lateral superior olivary (LSO) neurons, and hyperpolarizing inhibitory potentials were evoked by stimulation of the medial nucleus of the trapezoid body (MNTB). Both postsynaptic glycine and GABAA receptors could independently display LTD when isolated pharmacologically. Focal application of GABA, but not glycine, on the postsynaptic LSO neuron was sufficient to induce depression of the amino acid–evoked response, or MNTB-evoked inhibitory postsynaptic potentials. This GABA-mediated depression, in the absence of MNTB stimulation, was blocked by a GABAB receptor antagonist. To assess whether a change in neurotransmitter release is associated with the LTD, the polyvalent cation, ruthenium red, was used to increase the frequency of miniature inhibitory synaptic events. Consistent with a postsynaptic locus of expression, we found that the mean amplitude of miniature events decreased after LTD with no change in their frequency of occurrence. Furthermore, there was no change in the paired-pulse ratio or release kinetics of evoked inhibitory responses. Together, these results provide direct evidence that activity-dependent LTD of inhibition has a postsynaptic locus of induction and alteration, and that GABA but not glycine plays a pivotal role.

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A Controlled Release Codelivery System of MSCs Encapsulated in Dextran/Gelatin Hydrogel with TGF-β3-Loaded Nanoparticles for Nucleus Pulposus Regeneration

Stem Cells International ◽

10.1155/2016/9042019 ◽

2016 ◽

Vol 2016 ◽

pp. 1-14 ◽

Cited By ~ 11

Author(s):

Yibo Gan ◽

Sukai Li ◽

Pei Li ◽

Yuan Xu ◽

Liyuan Wang ◽

...

Keyword(s):

Controlled Release ◽

Nucleus Pulposus ◽

Release Kinetics ◽

Double Emulsion ◽

Plga Nanoparticles ◽

Gelatin Hydrogel ◽

Engineering Strategy ◽

A Cell

Mesenchymal stem cell- (MSC-) based therapy is regarded as a potential tissue engineering strategy to achieve nucleus pulposus (NP) regeneration for the treatment of intervertebral disc degeneration (IDD). However, it is still a challenge to induce MSC differentiation in NP-like cells when MSCs are implanted into the NP. The purpose of this study was to construct poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles as carriers for TGF-β3 controlled release and establish a codelivery system of a dextran/gelatin hydrogel with the nanoparticles for long-term processing of discogenesis differentiation. TGF-β3-loaded PLGA nanoparticles were prepared by the double-emulsion solvent evaporation method and seeded uniformly into the hydrogel. Morphological observations, an assessment of the release kinetics of TGF-β3, a cytotoxic assay, a cell proliferation test, a biochemical content assay, qRT-PCR, and immunohistological analyses of the codelivery system were conducted in the study. The results showed that the TGF-β3-loaded nanoparticles could release TGF-β3 gradually. The codelivery system exhibited favorable cytocompatibility, and the TGF-β3 that was released could induce MSCs to NP-like cells while promoting ECM-related biosynthesis. These results suggest this codelivery system may be employed as a promising carrier for discogenesis of MSCsin situ.

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