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Annals of the New York Academy of... Dec 2020Gastroesophageal reflux disease (GERD) is a condition with increasing prevalence and morbidity in the United States and worldwide. Despite advances in medical and... (Review)
Review
Gastroesophageal reflux disease (GERD) is a condition with increasing prevalence and morbidity in the United States and worldwide. Despite advances in medical and surgical therapy over the last 30 years, gaps remain in the therapeutic profile of options. Flexible upper endoscopy offers the promise of filling in these gaps in a potentially minimally invasive approach. In this concise review, we focus on the plethora of endoluminal therapies available for the treatment of GERD. Therapies discussed include injectable agents, electrical stimulation of the lower esophageal sphincter, antireflux mucosectomy, radiofrequency ablation, and endoscopic suturing devices designed to create a fundoplication. As new endoscopic treatments become available, we come closer to the promise of the incisionless treatment of GERD. The known data surrounding the indications, benefits, and risks of these historical, current, and emerging approaches are reviewed in detail.
Topics: Electric Stimulation; Esophageal Sphincter, Lower; Esophagoscopy; Fundoplication; Gastroesophageal Reflux; Humans; Polyvinyls; Radiofrequency Ablation
PubMed: 33063344
DOI: 10.1111/nyas.14511 -
International Journal of Molecular... Jan 2023As an energy storage technology, supercapacitors (SCs) have become an important part of many electronic systems because of their high-power density, long cycle life, and...
As an energy storage technology, supercapacitors (SCs) have become an important part of many electronic systems because of their high-power density, long cycle life, and maintenance-free characteristics. However, the widespread development and use of electronics, including SCs, have led to the generation of a large amount of e-waste. In addition, achieving compatibility between stability and biodegradability has been a prominent challenge for implantable electronics. Therefore, environmentally friendly SCs based on polypyrrole (PPy)-stabilized polypeptide (FF) are demonstrated in this study. The fully degradable SC has a layer-by-layer structure, including polylactic acid/chitosan (PLA-C) support layers, current collectors (Mg), FF/PPy composite layers, and a polyvinyl alcohol/phosphate buffer solution (PVA/PBS) hydrogel. It has the advantages of being light, thin, flexible, and biocompatible. After 5000 cycles in air, the capacitance retention remains at up to 94.7%. The device could stably operate for 7 days in a liquid environment and completely degrade in vitro within 90 days without any adverse effect on the environment. This work has important implications for eco-friendly electronics and will have a significant impact on the implantable biomedical electronics.
Topics: Polymers; Pyrroles; Polyvinyl Alcohol; Peptides
PubMed: 36768819
DOI: 10.3390/ijms24032497 -
Survey of Ophthalmology 2024Polyvinyl pyrrolidone or povidone-iodine (PVP-I) is a water-soluble complex formed by the combination of iodine and a water-soluble polymer, polyvinyl pyrrolidone. This... (Review)
Review
Polyvinyl pyrrolidone or povidone-iodine (PVP-I) is a water-soluble complex formed by the combination of iodine and a water-soluble polymer, polyvinyl pyrrolidone. This complex exerts bactericidal, fungicidal, and virucidal action by gradually releasing free iodine at the site of application to react with pathogens. In ophthalmology, PVP-I is used as a disinfectant and antiseptic agent for preoperative preparation of the skin and mucous membranes and for treating contaminated wounds. PVP-I has been shown to reduce effectively the risk of endophthalmitis in various ocular procedures, including cataract surgery and intravitreal injections; however, it has also been used in the treatment of conjunctivitis, keratitis, and endophthalmitis, with promising results especially in low-resource situations. PVP-I has been associated with complications such as postoperative eye pain, persistent corneal epithelial defects, ocular inflammation, and an attendant risk of keratitis. In cases of poor PVP-I tolerance, applying PVP-I at lower concentrations or using alternative antiseptics such as chlorhexidine should be considered. We provide an update on the efficacy of PVP-I in the prophylaxis and treatment of conjunctivitis, keratitis, and endophthalmitis and a comprehensive analysis of the current literature regarding the use of PVP-I in the management of these ocular conditions. Also, PVP-I-related adverse effects and toxicities and its alternatives are discussed. The goal is to present a thorough evaluation of the available evidence and to offer practical recommendations for clinicians regarding the therapeutic usage of PVP-I in ophthalmology.
Topics: Humans; Povidone-Iodine; Ophthalmology; Polyvinyls; Anti-Infective Agents, Local; Iodine; Cataract Extraction; Endophthalmitis; Povidone; Conjunctivitis; Keratitis; Water
PubMed: 37944600
DOI: 10.1016/j.survophthal.2023.11.002 -
Small (Weinheim An Der Bergstrasse,... Jun 2021Imperceptible electronics will make next-generation healthcare and biomedical systems thinner, lighter, and more flexible. While other components are thoroughly...
Imperceptible electronics will make next-generation healthcare and biomedical systems thinner, lighter, and more flexible. While other components are thoroughly investigated, imperceptible energy storage devices lag behind because the decrease of thickness impairs the area-specific energy density. Imperceptible supercapacitors with high area-specific capacitance based on reduced graphene oxide/polyaniline (RGO/PANI) composite electrodes and polyvinyl alcohol (PVA)/H SO gel electrolyte are reported. Two strategies to realize a supercapacitor with a total device thickness of 5 µm-including substrate, electrode, and electrolyte-and an area-specific capacitance of 36 mF cm simultaneously are implemented. First, the void volume of the RGO/PANI electrodes through mechanical compression is reduced, which decreases the thickness by 83% while retaining 89% of the capacitance. Second, the PVA-to-H SO mass ratio is decreased to 1:4.5, which improves the ion conductivity by 5000% compared to the commonly used PVA/H SO gel. Both advantages enable a 2 µm-thick gel electrolyte for planar interdigital supercapacitors. The impressive electromechanical stability of the imperceptible supercapacitors by wrinkling the substrate to produce folds with radii of 6 µm or less is demonstrated. The supercapacitors will be meaningful energy storage modules for future self-powered imperceptible electronics.
Topics: Electric Capacitance; Electric Conductivity; Electrodes; Electrolytes; Polyvinyl Alcohol
PubMed: 33977641
DOI: 10.1002/smll.202101704 -
Nature Nov 2021Inspired by living organisms, soft robots are developed from intrinsically compliant materials, enabling continuous motions that mimic animal and vegetal movement. In...
Inspired by living organisms, soft robots are developed from intrinsically compliant materials, enabling continuous motions that mimic animal and vegetal movement. In soft robots, the canonical hinges and bolts are replaced by elastomers assembled into actuators programmed to change shape following the application of stimuli, for example pneumatic inflation. The morphing information is typically directly embedded within the shape of these actuators, whose assembly is facilitated by recent advances in rapid prototyping techniques. Yet, these manufacturing processes have limitations in scalability, design flexibility and robustness. Here we demonstrate a new all-in-one methodology for the fabrication and the programming of soft machines. Instead of relying on the assembly of individual parts, our approach harnesses interfacial flows in elastomers that progressively cure to robustly produce monolithic pneumatic actuators whose shape can easily be tailored to suit applications ranging from artificial muscles to grippers. We rationalize the fluid mechanics at play in the assembly of our actuators and model their subsequent morphing. We leverage this quantitative knowledge to program these soft machines and produce complex functionalities, for example sequential motion obtained from a monotonic stimulus. We expect that the flexibility, robustness and predictive nature of our methodology will accelerate the proliferation of soft robotics by enabling the assembly of complex actuators, for example long, tortuous or vascular structures, thereby paving the way towards new functionalities stemming from geometric and material nonlinearities.
Topics: Biomimetic Materials; Polyvinyls; Robotics; Silicone Elastomers; Siloxanes
PubMed: 34759362
DOI: 10.1038/s41586-021-04029-6 -
Physical and Engineering Sciences in... Sep 2023TMP is gradually becoming a fundamental element for quality assurance and control in ionizing and non-ionizing radiation imaging modalities as well as in the development...
TMP is gradually becoming a fundamental element for quality assurance and control in ionizing and non-ionizing radiation imaging modalities as well as in the development of different techniques. This study aimed to evaluate and obtain polyvinyl chloride tissue mimicking material for dual-modality breast phantoms in mammography and ultrasound. Breast tissue equivalence was evaluated based on X-ray attenuation properties, speed of sound, attenuation, and acoustic impedance. There are six samples of PVC-plasticizer material with variations of PVC concentration and additives. The evaluation of X-ray attenuation was carried out using mammography from 23 to 35 kV, while the acoustic properties were assessed with mode A ultrasound and a transducer frequency of 5 MHz. A breast phantom was created from TMP material with tissue equivalence and was then evaluated using mammography as well as ultrasound to analyze its image quality. The results showed that samples A (PVC 5%, DOP 95%), B (PVC 7%, DOP 93%), C (PVC 10%, DOP 90%), E (PVC 7%, DOP 90%, graphite 3%), and F (PVC 7%, DOP 90%, silicone oil 3%) have the closest equivalent to the ACR breast phantom material with a different range of 0.01-1.39 in the 23-35 kV range. Based on the evaluation of the acoustic properties of ultrasound, A had high similarity to fat tissue with a difference of 0.03 (dB cm MHz) and 0.07 (10 kg m s), while B was close to the glandular tissue with a difference of 9.2 m s. Multilayer breast phantom images' results showed gray levels in mammography and ultrasound modalities. Therefore, this study succeeded in establishing TMP material for mammography and ultrasound. It can also be used for simple quality assurance and control programs.
Topics: Polyvinyl Chloride; Ultrasonography; Mammography; Phantoms, Imaging; Adipose Tissue
PubMed: 37253939
DOI: 10.1007/s13246-023-01283-y -
Small (Weinheim An Der Bergstrasse,... Apr 2021While piezoelectric nanogenerators have demonstrated the effective conversion of tiny mechanical vibrations to electricity, their performances are rarely examined under... (Review)
Review
While piezoelectric nanogenerators have demonstrated the effective conversion of tiny mechanical vibrations to electricity, their performances are rarely examined under harsh environmental conditions. Here, a multilayered polyvinylidene fluoride (PVDF) film-based piezoelectric nanogenerator (ML-PENG) is demonstrated to generate considerable and stable power outputs even at extremely low temperatures and pressures, and under strong UV. Up-/down-polarized PVDF films are alternately stacked, and Ag electrodes are intercalated between the two adjacent films. At -266 °C and 10 Torr, the ML-PENG generates an open-circuit voltage of 1.1 V, a short-circuit current density of 8 nA cm , and a power density of 4.4 nW cm . The piezoelectric outputs are quite stable against prolonged illumination of UV, large temperature- and pressure-variations, and excessive mechanical vibrations. The piezoelectric power density is greatly enhanced above the freezing and glass transition temperatures of PVDF and recorded to be 10, 105, and 282 nW cm at -73, 0, and 77 °C, respectively. The ML-PENG generates sufficient power to operate five light-emitting diodes by harvesting biomechanical energy under simulated Martian conditions. This work suggests that polarization- and electrode-optimized ML-PENG can serve as a reliable and economic power source in harsh and inaccessible environments like polar areas of Earth and extraterrestrial Mars.
Topics: Electrodes; Extraterrestrial Environment; Mars; Polyvinyls
PubMed: 33705597
DOI: 10.1002/smll.202007289 -
Polimery W Medycynie 2022As the number of new drug candidates that are poorly soluble in water grows, new technologies that enable the enhancement of their solubility are needed. This is the... (Review)
Review
As the number of new drug candidates that are poorly soluble in water grows, new technologies that enable the enhancement of their solubility are needed. This is the case with amorphous solid dispersions (ASDs) that, nowadays, not only ensure the solubility, but can also be used to control the release rate of poorly soluble drugs. However, this dosage form must overcome the major disadvantage of ASDs, which is limited stability upon storage. Thus, a thorough knowledge on polymeric carriers that can enhance drug solubility while ensuring stability in the amorphous form is necessary. In this review, the state of the art in the application of Kollidon® VA 64 (copovidone) and Soluplus® (graft copolymer of polyvinyl caprolactam-polyvinyl acetate and poly(ethylene glycol) (PEG)) in the manufacturing of ASDs over the last 20 years is presented. Apart from the classical methods, namely solvent evaporation or melting, more advanced technologies such as pulse combustion drying, high-speed electrospinning and single-step 3D printing are described. It has been shown that both the dissolution rate (in vitro) and enhancement in bioavailability (in vivo) regarding poorly soluble active ingredients of natural or synthetic origin are possible using these matrix-forming polymers.
Topics: Chemistry, Pharmaceutical; Drug Compounding; Polyethylene Glycols; Polymers; Polyvinyls; Povidone; Solubility
PubMed: 35766434
DOI: 10.17219/pim/150267 -
Journal of Colloid and Interface Science Jan 2021Conjugated polymer nanoparticles (CNPs) have attracted considerable attention within bioimaging due to their excellent optical properties and biocompatibility. However,...
HYPOTHESIS
Conjugated polymer nanoparticles (CNPs) have attracted considerable attention within bioimaging due to their excellent optical properties and biocompatibility. However, unspecific adsorption of proteins hampers their effective use as advanced bioimaging probes. Controlled methodologies made possible tailor-made functional poly(p-phenylene vinylene), enabling one-pot synthesis of CNPs containing functional surface groups. Hence, it should be feasible to PEGylate these CNPs to tune the uptake by cell lines representative for the brain without imparting their optical properties.
EXPERIMENTS
CNPs consisting of the statistical copolymer 2-(5'-methoxycarbonylpentyloxy)-5-methoxy-1,4-phenylenevinylene and poly(2-methoxy-5-(3',7'-dimethoxyoctyloxy)-1,4-phenylenevinylene) were fabricated by miniemulsion solvent evaporation technique. Surface carboxylic acid groups were used to covalently attach amine-terminated polyethylene glycol (PEG) of different molecular weights. We investigated the effect of grafting CNPs with PEG chains on their intrinsic optical properties, protein adsorption behavior and uptake by representative brain cell lines.
FINDINGS
PEGylation did not affect the optical properties and biocompatibility of our CNPs. Moreover, a significant decrease in protein corona formation and unspecific uptake in central nervous system cell lines, depending on PEG chain length, was observed. This is the first report indicating that PEGylation does not affect the CNPs role as excellent bioimaging tools and can be adapted to tune biological interactions with brain cells.
Topics: Nanoparticles; Polyethylene Glycols; Polymers; Polyvinyls
PubMed: 32818676
DOI: 10.1016/j.jcis.2020.07.145 -
Current Pharmaceutical Design 2023Diclofenac sodium has a short half-life (about 1.5 hours), requiring repeated administration, and as a result, serious complications, such as GI bleeding, peptic ulcer,...
BACKGROUND
Diclofenac sodium has a short half-life (about 1.5 hours), requiring repeated administration, and as a result, serious complications, such as GI bleeding, peptic ulcer, and kidney and liver dysfunction, are generated. Hence, a sustained/controlled drug delivery system is needed to overcome the complications caused by the administration of diclofenac sodium.
AIMS
This study aimed to fabricate and evaluate carbopol/polyvinyl alcohol-based pH-sensitive hydrogels for controlled drug delivery.
OBJECTIVE
pH-sensitive carbopol/polyvinyl alcohol graft-poly(acrylic acid) hydrogels (Cp/PVA-g-PAa hydrogels) were developed for the controlled delivery of diclofenac sodium.
METHODS
The combination of carbopol/polyvinyl alcohol, acrylic acid, and ethylene glycol dimethacrylate was used as polymer, monomer, and cross-linker, respectively. The effects of the formulation's composition on porosity, swelling index, and release pattern of diclofenac sodium from the developed hydrogels were investigated.
RESULTS
An increase in porosity and swelling was observed with the increasing amounts of carbopol and acrylic acid, whereas polyvinyl alcohol showed the opposite effect. Due to the formation of a highly viscous system, the drug release decreased with the increasing concentrations of carbopol and polyvinyl alcohol while increased with increasing acrylic acid concentration. The pH-responsive properties of the fabricated hydrogels were demonstrated by dynamic swelling and drug release studies at three different pH values. Higher dynamic swelling and diclofenac sodium (model drug) release were found at high pH values compared to low pH values, pH 7.4 > 4.6 > 1.2, respectively. Cytotoxicity studies reported no toxic effect of the prepared hydrogels, thus indicating that the prepared hydrogels are safe to be used on clinical basis.
CONCLUSION
The prepared carbopol/polyvinyl alcohol crosslinked hydrogel can be used as a promising carrier for the controlled release of drugs.
Topics: Humans; Polyvinyl Alcohol; Diclofenac; Cross-Linking Reagents; Drug Delivery Systems; Hydrogels; Hydrogen-Ion Concentration; Drug Liberation
PubMed: 37881070
DOI: 10.2174/0113816128268132231016061548