Synthetic Hydrophilic Polymers Research Articles

RECENT TRENDS IN DIFFERENT TYPES OF SYNTHETIC HYDROPHILIC POLYMER NANOPARTICLES, METHODS OF SYNTHESIS & THEIR APPLICATIONS

Numerous types of hydrophilic polymer nanoparticles (NPs) have recently become research hotspots because of their ability to dissolve in water and can be adapted with respect to physical, chemical, and biological properties to meet the requirements of different applications. Synthetic hydrophilic polymeric NPs had successfully gained much attention because of their unique physicochemical properties, such as low toxicity, biodegradability, bioavailability, and support material for extensive swelling in water. These synthetic hydrophilic polymers NPs create new opportunities to produce water-soluble polymer types that would be able to imitate the structure and function of biological polymers. Several synthetic hydrophilic polymer NPs that gain high interest recently including poly(N-isopropyl acrylamide) (PNIPAM), poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA) and poly(N-(2-hydroxypropyl) methacrylamide (PHPMA) are reviewed in this paper. Furthermore, various synthesis methods to produce synthetic hydrophilic polymer NPs for instance emulsion polymerization, microemulsion polymerization and inverse miniemulsion polymerization are highlighted, and a brief overview on their recent applications especially in medical applications are also be discussed thoroughly in this review.

Dextran Methacrylate Reactions with Hydroxyl Radicals and Hydrated Electrons in Water: A Kinetic Study Using Pulse Radiolysis.

Dextran methacrylate (Dex-MA) is a biodegradable polysaccharide derivative that can be cross-linked by ionizing radiation. It is therefore considered a potential replacement for synthetic hydrophilic polymers in current radiation technologies used for synthesizing hydrophilic cross-linked polymer structures such as hydrogels, mainly for medical applications. This work is focused on the initial steps of radiation-induced cross-linking polymerization of Dex-MA in water. Rate constants of two major transient water radiolysis products-hydroxyl radicals (•OH) and hydrated electrons (eaq-)-with various samples of Dex-MA (based on 6-500 kDa dextrans of molar degree of substitution or DS with methacrylate groups up to 0.66) as well as non-substituted dextran were determined by pulse radiolysis with spectrophotometric detection. It has been demonstrated that these rate constants depend on both the molecular weight and DS; reasons for these effects are discussed and reaction mechanisms are proposed. Selected spectral data of the transient species formed by •OH- and eaq--induced reactions are used to support the discussion. The kinetic data obtained in this work and their interpretation are expected to be useful for controlled synthesis of polysaccharide-based hydrogels and nanogels of predefined structure and properties.

STUDY OF ISOTHERMS OF WATER VAPOR SORPTION FOR HYDROPHILIC POLYMERS

Various models and equations of water vapor (WV) sorption for hydrophilic polymers were considered. However, these models often do not correspond to the sorption mechanism. This study is based on the thermodynamics in binary systems and the Van Krevelen method of polar group contributions in the sorption of WV. Moreover, it was shown that the mechanism of WV sorption by various hydrophilic polymers is the absorption of water molecules in the volume of amorphous domains of these polymers. As a result, a universal physicochemical equation was proposed allowing adequately to describe the sorption isotherms of WV by amorphous hydrophilic polymers knowing only the chemical formulas of repeating units of these polymers. To calcu-late the sorption isotherms for semicrystalline polymer samples, it is necessary to use an additional parameter, namely the degree of amorphicity (Y). The adequacy of the derived equation was verified for samples of cellulose and other natural polysaccharides, as well as for samples of synthetic hydrophilic polymers such as polyvinyl alcohol, polyamide-6, and polycaprolactone having various Y-values. The verification showed that the experimental isotherms are almost identical to the isotherms calculated by the universal equation.

Biocompatibility and osteogenic potential of mineral trioxide aggregate mixed with hydrophilic synthetic polymer: An in vitro and in vivo study.

This study aimed to investigate in vitro biologic properties of mineral trioxide aggregate (MTA) mixed with 3% PVA (MTA-3% PVA) and in vivo dental pulp responses to direct capping in comparison with MTA mixed with distilled water (MTA-DW). Cell proliferation and osteogenic differentiation in culture of human dental pulp cells (hDPCs), and pH changes were evaluated. Pulps in 24 mandibular premolars of four 9-month-old beagle dogs were mechanically exposed and direct pulp capping was performed. Histological specimens were scored according to the degree of mineralization. MTA-3% PVA showed similar cell proliferation and similar or superior osteogenic differentiation of hDPCs compared with MTA-DW. All specimens were associated with calcified bridge formation and there were no significant differences in mineralization scores between the groups (p>0.05). The results suggested that MTA-3% PVA exhibited favorable biocompatibility and osteogenic differentiation in vitro compared with MTA-DW. Furthermore, both groups demonstrated similar results when used as pulp-capping agents in vivo.

Islet Encapsulation: New Developments for the Treatment of Type 1 Diabetes.

Islet transplantation is a promising approach for the treatment of type 1 diabetes (T1D). Currently, clinical islet transplantation is limited by allo - and autoimmunity that may cause partial or complete loss of islet function within a short period of time, and long-term immunosuppression is required to prevent rejection. Encapsulation into semipermeable biomaterials provides a strategy that allows nutrients, oxygen and secreted hormones to diffuse through the membrane while blocking immune cells and the like out of the capsule, allowing long-term graft survival and avoiding long-term use of immunosuppression. In recent years, a variety of engineering strategies have been developed to improve the composition and properties of encapsulation materials and to explore the clinical practicality of islet cell transplantation from different sources. In particular, the encapsulation of porcine islet and the co-encapsulation of islet cells with other by-standing cells or active ingredients for promoting long-term functionality, attracted significant research efforts. Hydrogels have been widely used for cell encapsulation as well as other therapeutic applications including tissue engineering, cell carriers or drug delivery. Here, we review the current status of various hydrogel biomaterials, natural and synthetic, with particular focus on islet transplantation applications. Natural hydrophilic polymers include polysaccharides (starch, cellulose, alginic acid, hyaluronic acid, chitosan) and peptides (collagen, poly-L-lysine, poly-L-glutamic acid). Synthetic hydrophilic polymers include alcohol, acrylic acid and their derivatives [poly (acrylic acid), poly (methacrylic acid), poly(acrylamide)]. By understanding the advantages and disadvantages of materials from different sources and types, appropriate materials and encapsuling methods can be designed and selected as needed to improve the efficacy and duration of islet. Islet capsule transplantation is emerging as a promising future treatment for T1D.

Models of Water Vapor Sorption by Hydrophilic Polymers

Various models and equations of water vapor sorption by hydrophilic polymers were considered. It was shown that these models often do not correspond to the sorption mechanism. These models can be mathematically adapted to the experimental isotherm regardless of the real sorption mechanism. Even when sorption occurs according to the same mechanism, various authors use different models and equations. This study is based on the volume absorption mechanism and the Van Krevelen method of group contributions. As a result, a universal physicochemical equation was proposed, which makes it possible to adequately describe the sorption isotherms of amorphous hydrophilic polymers knowing only the chemical formulas of repeating units of these polymers. To calculate the sorption isotherms for semicrystalline samples, it is necessary to use an additional parameter, namely the degree of amorphicity (Y). The adequacy of the derived equation was verified for samples of cellulose and other natural polysaccharides, as well as for samples of synthetic hydrophilic polymers such as polyvinyl alcohol, polyamide-6, and polycaprolactone having various Y-values. The verification showed that the experimental isotherms are almost identical to the isotherms calculated by the universal equation.

Engineering of 3D polymer network hydrogels for biomedical applications: a review

The 3D polymer network of hydrogels got immense importance because of distinctive characteristics like high water content, flexible and soft nature, biodegradable, and biocompatible behavior. These materials can be produced by physical or chemical cross-linking of the usual natural and synthetic hydrophilic polymer chains into a 3D network structure. The resemblances of hydrogels with the living body tissues make these materials to be applied extensively in the biomedical field. The present study emphasizes the main characteristics and use of hydrogels in biomedical fields. This review provides the reader with a comprehensive detail of the polymer hydrogel based inventions and products as well as perspective on future potential developments.

Poly(vinyl alcohol) nanocomposites: Recent contributions to engineering and medicine

<abstract> Poly(vinyl alcohol) is a water soluble hydrophilic synthetic polymer. As a matrix it can be mixed with fillers having nano dimensions to form polymer nanocomposites with interesting properties, different than those of PVA. From the chemical point of view nanofillers can be elements such as Au, Ag, Se, oxides such as CuO, SrO, TiO₂, graphene oxide, minerals like hallosite, montmorillonite, tubes such as carbon nanotubes, hallosite nano tubes, etc. As presented in this review, some of the nanofillers are able to change and improve poly(vinyl alcohol)'s mechanical, thermal, and electrical properties, and can find uses in medicine. In the latter, due to the fact that poly(vinyl alcohol) is biocompatible, biodegradable, and bioabsorbant, it is possible to produce poly(vinyl alcohol) nanocomposites to be used like antibacterial, tissue engineering, drug carrier, wound dressing, etc. The present article retains the most recent (2019–2020) studies done on poly(vinyl alcohol) nanocomposites structure and contributions to engineering and medicine. </abstract>

Comprehensive Bioanalysis of Ultrahigh Molecular Weight, Highly Disperse Poly(ethylene oxide) in Rat via Microsolid Phase Extraction and RPLC-Q-Q-TOF Coupled with the MSALL Technique.

Ultrahigh molecular weight (UHMW) poly(ethylene oxide) (PEO) is a synthetic hydrophilic polymer with wide dispersity which shows considerable promise as a hemostatic agent in the treatment of gastrointestinal bleeding. Currently there is no analytical method for the determination of highly disperse UHMW PEO in biological samples that would allow its characterization in vivo and support its clinical development. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful bioanalytical tool, it faces major challenges when applied to UHMW PEO. In this work, we report a novel bioanalytical method for the determination of UHMW PEO involving microsolid phase extraction (μ-SPE), chromatography on a PLRP-S 1000 Å reversed phase column and detection by positive ion Q-Q-TOF MS using the MSALL technique. In this mode, dissociation of all precursor ions in Q2 generated a series of product ions at m/z 89.0715, 133.0854, 177.1047, and 221.1475 of which the product ion at m/z 133.0854 was common to all precursor ions and enabled quantitation of all polymers in UHMW PEO. The method was successfully applied to the determination of UHMW PEO polymers in rat plasma, urine, and feces after oral administration of 1700 kDa PEO. The results show that UHMW PEO is not absorbed into the blood and is largely eliminated unchanged in feces over 48 h. We maintain the method is sufficiently robust to be used in routine bioanalysis of polymers with UHMW and wide dispersity.

Freeform, Reconfigurable Embedded Printing of All-Aqueous 3D Architectures.

Aqueous microstructures are challenging to create, handle, and preserve since their surfaces tend to shrink into spherical shapes with minimum surface areas. The creation of freeform aqueous architectures will significantly advance the bioprinting of complex tissue-like constructs, such as arteries, urinary catheters, and tracheae. The generation of complex, freeform, three-dimensional (3D) all-liquid architectures using formulated aqueous two-phase systems (ATPSs) is demonstrated. These all-liquid microconstructs are formed by printing aqueous bioinks in an immiscible aqueous environment, which functions as a biocompatible support and pregel solution. By exploiting the hydrogen bonding interaction between polymers in ATPS, the printed aqueous-in-aqueous reconfigurable 3D architectures can be stabilized for weeks by the noncovalent membrane at the interface. Different cells can be separately combined with compartmentalized bioinks and matrices to obtain tailor-designed microconstructs with perfusable vascular networks. The freeform, reconfigurable embedded printing of all-liquid architectures by ATPSs offers unique opportunities and powerful tools since limitless formulations can be designed from among a breadth of natural and synthetic hydrophilic polymers to mimic tissues. This printing approach may be useful to engineer biomimetic, dynamic tissue-like constructs for potential applications in drug screening, in vitro tissue models, and regenerative medicine.

Dissolvable Polyvinyl-Alcohol Film, a Time-Barrier to Modulate Sample Flow in a 3D-Printed Holder for Capillary Flow Paper Diagnostics.

Integrating a dissolvable membrane into a sensor allows the control of sample flow, location and duration in critical areas. These time-barrier films stop the flow of samples until the membrane has dissolved, thus, for example, allowing increased exposure time between immunoreagents for the formation of greater numbers of immuno-complexes, ensuring higher sensitivity, reactivity, and helping to reduce false-positive signals. In this study, dissolvable polyvinyl alcohol (PVA) films are used in a 3D-printed sensor holder, which enables film integration without the use of glue. PVA is a synthetic hydrophilic linear polymer, its solubility is dependent on its molecular weight and degree of hydrolysis. Three types of PVAs films were tested herein: (1) PVA 1-Mw: 30–70 K, 87–90% hydrolyzed; (2) PVA 2-Mw: 31–50 K, 98–99% hydrolyzed and (3) PVA 3-Mw: 89–98 K, >99% hydrolyzed. The films were exposed to water in (1) the novel 3D-printed holder and (2) directly immersed into a water droplet. After comparing the time taken to dissolve PVA 1–3 films, PVA 1 films of 5–20% (w/v) are found to be most suitable as time barrier films, due to their optimal dissolution times and physical properties for integration into the customized 3D-printed holder.

NOVEL APPROACH OF EXTRACTION AND CHARACTERIZATION OF OKRA GUM AS A BINDER FOR TABLET FORMULATION

Objective: The major objective of the present investigation was to extract a natural polymer (okra gum) with its characterization as pharmaceutical binder and to formulate, develop, and evaluate the compression-coated tablet using okra as binder along with synthetic hydrophilic polymers like various grades of hydroxypropyl methylcellulose (HPMC).Methods: A novel extraction method was carried out using fresh unripe pods of okra (ladies finger) with the aid of organic solvents and its characterization was done. The core tablets were prepared by direct compression method which was compression coated with okra gum and HPMC.Results: After the extraction of the okra gum was carried out, the yield of mucilage obtained was 10%. It is considered as a proof for the purity of the mucilage extract. The above study reveals that the polymers were subjected to the Fourier transform infrared and differential scanning calorimetry thermogram had no significant interactions between the drug and the polymers. The characterization of the new polymer okra showed that it has swelling properties, and in spite of being a hydrophilic polymer, it can be successfully used in pharmaceutical formulation as a good binder.Conclusion: In the present aspect of the study was to evaluate the efficacy of okra gum that has been used as a tablet binder. It is easily available and inexpensive. Okra gum as a binder produces tablet formulations with good physicochemical properties and good candidate for sustained release formulations.

NOVEL APPROACH OF EXTRACTION AND CHARACTERIZATION OF OKRA GUM AS A BINDER FOR TABLET FORMULATION

Objective: The major objective of the present investigation was to extract a natural polymer (okra gum) with its characterization as pharmaceutical binder and to formulate, develop, and evaluate the compression-coated tablet using okra as binder along with synthetic hydrophilic polymers like various grades of hydroxypropyl methylcellulose (HPMC).Methods: A novel extraction method was carried out using fresh unripe pods of okra (ladies finger) with the aid of organic solvents and its characterization was done. The core tablets were prepared by direct compression method which was compression coated with okra gum and HPMC.Results: After the extraction of the okra gum was carried out, the yield of mucilage obtained was 10%. It is considered as a proof for the purity of the mucilage extract. The above study reveals that the polymers were subjected to the Fourier transform infrared and differential scanning calorimetry thermogram had no significant interactions between the drug and the polymers. The characterization of the new polymer okra showed that it has swelling properties, and in spite of being a hydrophilic polymer, it can be successfully used in pharmaceutical formulation as a good binder.Conclusion: In the present aspect of the study was to evaluate the efficacy of okra gum that has been used as a tablet binder. It is easily available and inexpensive. Okra gum as a binder produces tablet formulations with good physicochemical properties and good candidate for sustained release formulations.

Cilostazol-loaded electrospun three-dimensional systems for potential cardiovascular application: Effect of fibers hydrophilization on drug release, and cytocompatibility

Currently marketed drug-eluting stents are non-selective in their anti-restenotic action. New active substance introduction to polymeric stents and vascular grafts can promote early re-endothelialization, crucial in preventing implant restenosis. Additionally, managing material hydrophobicity by blending synthetic polymers limits adverse effects on bulk properties and controls active substance release. However, the influence of hydrophilic synthetic polymer on human cells in the cardiovascular system remains to be determined. In this report, effects of both poly(ε-caprolactone) (PCL) fibers hydrophilization with Pluronic P123 (P123) and cilostazol (CIL) loading were studied.Physicochemical and mechanical properties of electrospun tubular structures produced from PCL and PCL/P123 fibers with and without CIL were investigated and compared. Release profiles studies and in vitro cell proliferation assays of electrospun materials were conducted. It was found that P123 located near the surface of electrospun fibers increased the rate of CIL release. PCL formulation sustained human umbilical vein endothelial cells (HUVEC) growth for 48 h. Despite improved hydrophilicity, PCL/P123 formulations were found to reduce HUVEC viability. Both PCL and PCL/P123 materials reduced primary aortic smooth muscle cells (PASM) viability after 48 h. In PCL formulations containing CIL, drug release caused a decrease in PASM viability. P123 blending with PCL was found to be as a useful pre-fabrication technique for modulating surface hydrophobicity of electrospun materials and the release profile of incorporated active substance. The cytotoxicity of P123 was evaluated to improve the design of drug-loaded vascular grafts for cardiovascular applications.

Natural and Synthetic Hydrophilic Polymers Enhance Salt and Drought Tolerance of Metasequoia glyptostroboides Hu and W.C.Cheng Seedlings

We compared the effects of hydrophilic polymer amendments on drought and salt tolerance of Metasequoia glyptostroboides Hu and W.C.Cheng seedlings using commercially available Stockosorb and Luquasorb synthetic hydrogels and a biopolymer, Konjac glucomannan (KGM). Drought, salinity, or the combined stress of both drought and salinity caused growth retardation and leaf injury in M. glyptostroboides. Under a range of simulated stress conditions, biopolymers and synthetic hydrogels alleviated growth inhibition and leaf injury, improved photosynthesis, and enhanced whole-plant and unit transpiration. For plants subjected to drought conditions, Stockosorb hydrogel amendment specifically caused a remarkable increase in water supply to roots due to the water retention capacity of the granular polymer. Under saline stress, hydrophilic polymers restricted Na+ and Cl− concentrations in roots and leaves. Moreover, root K+ uptake resulted from K+ enrichment in Stockosorb and Luquasorb granules. Synthetic polymers and biopolymers increased the ability of M. glyptostroboides to tolerate combined impacts of drought and salt stress due to their water- and salt-bearing capacities. Similar to the synthetic polymers, the biopolymer also enhanced M. glyptostroboides drought and salt stress tolerance.

Influence of Chitosan Molecular Weight and Poly(ethylene oxide): Chitosan Proportion on Fabrication of Chitosan Based Electrospun Nanofibers

Fabrication of electrospun chitosan nanofibers is still a controversial issue in publications. Although regarding the lots of reports, mixtures of chitosan with a hydrophilic synthetic polymer such as polyethylene oxide (PEO) have been electrospun successfully, abundance of partly contradictory protocols in which one variable has been surveyed in each study is unfortunately baffling. In the present study, influence of three considerable parameters including the average molecular weight of chitosan, chitosan solution concentration and the mass ratio of polyethylene oxide to chitosan at the mixtures on electrospinning possibility as well as the quality of as-spun fibers is investigated. Eventually, the necessities for obtaining the best results are introduced followed by further analysis of optimized nanofibers using atomic force microscopy. According to our results, the blend solutions prepared from the low molecular weight (LMW) chitosan and PEO are efficient for reproducible production of bead-free electrospun nanofibers even in low proportion of polyethylene oxide.

Mechanical properties and microstructure analysis of mineral trioxide aggregate mixed with hydrophilic synthetic polymer.

In dentistry, mineral trioxide aggregate (MTA) has been widely used for root perforation, retrograde filling, pulp capping and regenerative endodontics. Despite its superior sealing ability and biocompatibility, MTA has critical drawbacks regarding handling property such as sandy property, lacking cohesive properties and wash-out tendency. So, it is necessary to improve the fluidity of MTA in order to improve its handling properties. In this study, we applied modified liquid to improve handling properties of MTA. Polyvinyl alcohol (PVA; 3 and 5 wt %) aqueous solutions were prepared and the samples were divided into three groups: DW group (MTA mixed with distilled water), P3 group (MTA mixed with 3% PVA), and P5 group (MTA mixed with 5% PVA). Handling property, initial setting time, and compressive strength were evaluated. The microstructures were observed by Field emission scanning electron microscope (FE-SEM) and X-ray diffractometer (XRD) phase analyses were performed. PVA modified group showed similar behavior of IRM compared to DW group. The initial setting time of P3 or P5 group was significantly longer than that of DW group (p < 0.05). The compressive strength of DW group was higher than that of P3 or P5 groups (p < 0.05). Experimental groups (P3 and P5) showed no microstructural differences compared with DW group when the fractured surfaces were observed by FE-SEM with XRD patterns after 3 and 14 days. Polyvinyl alcohol, a modified liquid for MTA, improved the handling properties of the material without violating its microstructure.

Formulation of gastroretentive floating drug delivery system using hydrophilic polymers and its in vitro characterization

The aim of the present research is to formulate and evaluate the gastroretentive floating drug delivery system of antihypertensive drug, propranolol HCl. Gastroretentive floating tablets (GRFT) were prepared by using a synthetic hydrophilic polymer polyethylene oxide of different grades such as PEO WSR N-12 K and PEO 18 NF as release retarding polymers and calcium carbonate as gas generating agent. The GRFT were compressed by direct compression strategy and the tablets were evaluated for physico-chemical properties, in vitro buoyancy, swelling studies, in vitro dissolution studies and release mechanism studies. From the dissolution and buoyancy studies, F 9 was selected as an optimized formulation. The optimized formulation followed zero order rate kinetics with non-Fickian diffusion mechanism. The optimized formulation was characterised with FTIR studies and observed no interaction between the drug and the polymers.

Avidin-conjugated polymers with monobiotinylated antibody fragments: A new strategy for the noncovalent attachment of recombinant proteins for polymer therapeutics

The high affinity and specificity between avidin and biotin were employed to bind a recombinant single-chain antibody fragment to synthetic hydrophilic polymer drug carriers. Two semitelechelic polymers, based on poly(ethylene glycol) and poly[ N-(2-hydroxypropyl)methacrylamide], each containing a single thiol end group, were conjugated to dithiopyridyl-modified avidin. The biotinylated recombinant single-chain antibody fragment of the M75 antibody was then noncovalently bound to the polymer-avidin conjugates. The recombinant protein was chosen as a targeting ligand against carbonic anhydrase IX, a marker overexpressed by tumor cells of various human carcinomas. The antigen-binding affinity of the polymer–single-chain antibody fragment complex was confirmed by enzyme-linked immuno sorbent assay (ELISA). This approach provides an original, nondestructive way of preparing supramolecular systems intended for targeted delivery of therapeutics utilizing modern chemical procedures, including reversible addition–fragmentation chain-transfer polymerization and recombinant DNA techniques.

ChemInform Abstract: Amphiphilic Systems Based on Polysaccharides Produced by Solid‐phase Synthesis ‐ A Review

AbstractReview: 21 refs.