Ice Confinement Enabled Click Conjugation of DNA Oligonucleotides and Macromolecules.

Polymer scaffolds are increasingly ubiquitous in the field of tissue engineering in improving the repair and regeneration of damaged tissue. Natural polymers exhibit better cellular adhesion and proliferation than biodegradable synthetics but exhibit inferior mechanical properties, among other disadvantages. Synthetic polymers are highly tunable but lack key binding motifs that are present in natural polymers. Using collagen and poly(lactic acid) (PLA) as models for natural and synthetic polymers, respectively, an evaluation of the cellular response of embryonic mouse fibroblasts (NIH 3T3 line) to the different polymer types was conducted. The samples were analyzed using LIVE/DEAD™, alamarBlue™, and phalloidin staining to compare cell proliferation on, interaction with, and adhesion to the scaffolds. The results indicated that NIH3T3 cells prefer collagen-based scaffolds. PLA samples had adhesion at the initial seeding but failed to sustain long-term adhesion, indicating an unsuitable microenvironment. Structural differences between collagen and PLA are responsible for this difference. Incorporating cellular binding mechanisms (i.e., peptide motifs) utilized by natural polymers into biodegradable synthetics offers a promising direction for biomaterials to become biomimetic by combining the advantages of synthetic and natural polymers while minimizing their disadvantages.

Natural and synthetic polymers are a versatile platform for developing biomaterials in the biomedical and environmental fields. Natural polymers are organic compounds that are found in nature. The most common natural polymers include polysaccharides, such as alginate, hyaluronic acid, and starch, proteins, e.g., collagen, silk, and fibrin, and bacterial polyesters. Natural polymers have already been applied in numerous sectors, such as carriers for drug delivery, tissue engineering, stem cell morphogenesis, wound healing, regenerative medicine, food packaging, etc. Various synthetic polymers, including poly(lactic acid), poly(acrylic acid), poly(vinyl alcohol), polyethylene glycol, etc., are biocompatible and biodegradable; therefore, they are studied and applied in controlled drug release systems, nano-carriers, tissue engineering, dispersion of bacterial biofilms, gene delivery systems, bio-ink in 3D-printing, textiles in medicine, agriculture, heavy metals removal, and food packaging. In the following review, recent advancements in polymer chemistry, which enable the imparting of specific biomedical functions of polymers, will be discussed in detail, including antiviral, anticancer, and antimicrobial activities. This work contains the authors' experimental contributions to biomedical and environmental polymer applications. This review is a vast overview of natural and synthetic polymers used in biomedical and environmental fields, polymer synthesis, and isolation methods, critically assessessing their advantages, limitations, and prospects.

Various nanomaterials have been studied for their biomedical application in recent years. Among them, nanocomposites have a prominent medical application in the prevention, diagnosis, and treatment of various diseases. Nanocomposites are made up of polymeric matrix layers composed of synthetic or natural polymers like chitosan, polyethylene glycol, etc. Polymer nanocomposites are inorganic nanoparticles dispersed in a polymer matrix. There are two types of polymeric nanocomposites which include natural and synthetic polymer nanocomposites. These nanocomposites have various biomedical applications, such as medical implants, wound healing, wound dressing, bone repair and replacement, and dental filling. Polymeric nanocomposites have a wide range of biomedical applications due to their high stability, non-immunogenic nature, sustained drug delivery, non-toxic, and can escape reticuloendothelial system uptake along with drug bioavailability improvement. In this review, we have discussed various types of natural and synthetic polymer nanocomposites and their biomedical applications.

Fibroblasts are important for the successful healing of deep wounds. However, the influence exerted by Cuticell, a natural polymer on fibroblasts and by the synthetic polymer, Suprathel, made of poly-L-lactic acid, is not sufficiently characterised. This study compared the survival and growth characteristics of human juvenile and adult dermal fibroblasts as well as murine fibroblast cell line L929, on a natural polymer with those of a synthetic polymer using different culture models. Murine, juvenile and adult human fibroblasts were seeded on both the natural and synthetic polymers using statical slide culture or the medium air interface and dynamical rotatory culture. Cell adherence, viability, morphology and actin cytoskeleton architecture were monitored for 1-7 days. Biomaterial permeability was checked with a previously established diffusion chamber. The majority of the murine and adult human fibroblasts survived in slide and rotatory cultures on both wound dressings. The fibroblasts seeded on the synthetic polymer exhibited phenotypically a typical spread shape with multiple cell adhesion sites earlier than those on the natural polymer. The highest survival rates in all tested fibroblast species over the entire observation time were detected in rotatory culture (mean: >70%). Nevertheless, it led to cell-cluster formation on both materials. In the medium air interface culture, few adult fibroblasts adhered and survived until the seventh day of culture on both the natural and synthetic polymers, and no viable juvenile and L929 fibroblasts could be found by day seven. Apart from a significant higher survival rate of L929 in slide culture on the natural polymer compared with the synthetic polymer at the end of the culturing period (p<0.0001), and a higher cell survival of L929 on the natural polymer in medium air interface culture, only minor differences between both materials were evident. This suggested a comparable cytocompatibility of both materials. Permeability testing revealed slightly higher permeance of the natural polymer compared with the synthetic polymer. Cell survival rates depended on the culture system and the fibroblast source. Nevertheless, the juvenile skin fibroblasts were the most sensitive. This observation suggests that wound dressings used in treating children should be tested beforehand with juvenile fibroblasts to ensure the dressing does not compromise wound healing. Future experiments should also include the response of compromised fibroblasts, for example, from burn patients.

Object: The objective of the present study was to investigate the effect of various concentrations of natural and synthetic polymers on in vitro drug release from sustained release matrix tablets. Materials and method: HPMC K4M and acacia gum were used as synthetic (hydrophilic) and natural (hydrophobic) polymers respectively. Diclofenac sodium was used as a model drug to study the in vitro release profile. Matrix tablets of Diclofenac sodium were fabricated by varying the concentrations of both natural and synthetic polymer via direct compression method. Result: The results of all evaluation parameters of the matrix tablet were within the acceptable limit. A significant difference was observed on in vitro drug release due to difference in polymers and their concentration. HPMC K4M in the concentration of 7% w/v showed 88.20 ± 0.056% cumulative drug release at the end of 10 h while the same concentration of acacia showed 85.22% ± 0.045%. The release mechanism of matrix tablet followed zero order release kinetics. The finding of current investigation clearly indicates that the synthetic polymer was given a more sustained release profile than natural polymer on varied concentration. Conclusion: On comparing in vitro release of optimized formulation with marketed preparation, it was concluded that F3 was found to be more efficient and promising than marketed preparation.

Abstract

The difficulty in treating chronic wounds due to the prolonged inflammation stage has affected a staggering 6.5 million people, accompanied by 25 billion USD annually in the United States alone. A 1.9% rise in chronic wound prevalence among Medicare beneficiaries was reported from 2014 to 2019. Besides, the global wound care market values were anticipated to increase from USD 20.18 billion in 2022 to USD 30.52 billion in 2030, suggesting an expected rise in chronic wounds financial burdens. The lack of feasibility in using traditional dry wound dressings sparks hydrogel development as an alternative approach to tackling chronic wounds. Since ancient times, honey has been used to treat wounds, including burns, and ongoing studies have also demonstrated its wound-healing capabilities on cellular and animal models. However, the fluidity and low mechanical strength in honey hydrogel necessitate the incorporation of other polymers. Therefore, this review aims to unravel the characteristics and feasibility of natural (chitosan and gelatin) and synthetic (polyvinyl alcohol and polyethylene glycol) polymers to be incorporated in the honey hydrogel. Relevant articles were identified from databases (PubMed, Google Scholar, and Science Direct) using keywords related to honey, hydrogel, and polymers. Relevant data from selected studies were synthesized narratively and reported following a structured narrative format. The importance of honey's roles and mechanisms of action in wound dressings were discussed. Notable studies concerning honey hydrogels with diverse polymers were also included in this article to provide a better perspective on fabricating customized hydrogel wound dressings for various types of wounds in the future. Honey's incapability to stand alone in hydrogel requires the incorporation of natural and synthetic polymers into the hydrogel. With this review, it is hoped that the fabrication and commercialization of the desired honey composite hydrogel for wound treatment could be brought forth.

The effects of type and content of polymer functional groups on the adsorption mechanism on the chromium (III) oxide surface were studied. Both synthetic [poly(acrylic acid) (PAA), anionic polyacrylamide (PAM), poly(aspartic acid) (ASP), block co-polymer of ASP with poly(ethylene glycol) (ASP-b-PEG)] and natural [bovine serum albumin, ovalbumin, human serum albumin, bacterial polysaccharide (exopolysaccharide EPS)] polymers were applied. For this purpose, adsorption, surface charge, zeta potential and stability measurements were carried out. The largest adsorption was found for the ASP-b-PEG (synthetic polymer) and EPS (natural polymer). The most effective destabilizers for Cr2O3 removal from the aqueous suspension were PAA 240,000 and ASP 6800.

The complexity of synthetic and natural polymers used in industrial and medical applications is expanding; thus, it becomes increasingly important to improve and develop methods for their molecular characterization. Free-solution capillary electrophoresis is a robust technique for the separation and characterization of both natural and synthetic complex charged polymers. In the case of polyelectrolytes, free-solution capillary electrophoresis is in the "critical conditions" (CE-CC): it allows their separation by factors other than molar mass for molar masses typically higher than 20000 g/mol. This method is thus complementary to size-exclusion chromatography (SEC). SEC is widely used to determine molar mass distributions and their dispersities. Utilizing CE-CC, an analogous calculation of dispersity based on the distributions of electrophoretic mobilities was derived and the heterogeneity of composition or branching in different polysaccharides or synthetic polymers was obtained in a number of experimental cases. Calculations are based on a ratio of moments and could therefore be compared to simulations of polymerization processes, in analogy to the work performed on molar mass distributions. Among four possible types of dispersity, the most precise values were obtained with the calculation analogous with the dispersity of molar mass distribution Mw/Mn. In addition, the dispersity value allows conclusions based on a single value: the closer the dispersity is to 1, the more homogeneous the polymer is in terms of composition or branching. This approach allows the analysis of dispersity of important molecular attributes of polymers other than molar mass and aims at improving the overall molecular characterization of both synthetic and natural polymers. The dispersity can also be monitored online while performing a chemical reaction within the CE instrument.

Poly (vinyl alcohol) and hyaluronic acid hydrogels as potential biomaterial systems - A comprehensive review

A review on versatile applications of blends and composites of CNC with natural and synthetic polymers with mathematical modeling

Technology Today Series Introduction The 1990's have seen a surge in new water-soluble polymers available to the drilling industry. Many new polymers offer enhancements or significant improvements. It has often been said that "This polymer system is just as good as oil mud," or "This product will replace oil mud." These claims have negatively affected acceptance of new polymers, retarding their field applications regardless of technical and/or economic merit. Many new polymers are gaining acceptance because of unique performance characteristics and are proving to be cost-effective. Other polymers have been slow to gain acceptance, not because of improper claims, but because of less-than-satisfactory technical and/or economic performance. Some polymers will never achieve stated claims, but others will be optimized or modified and find an application niche in the industry. No one polymer chemistry or system will replace all the performance characteristics of oil-based fluids; however, some polymers are being used successfully in some oil-mud applications. Polymer Classification Overview Polymers are used in virtually all water-based fluids, so the term"polymer" should not have a negative connotation. However, many in the industry view polymers negatively because of a lack of understanding. Also, many drillers, drilling superintendents, and drilling engineers have seen on location that polymers fail to achieve claims. Polymers are classified as natural, modified natural, and synthetic. Natural polymers originate in nature (i.e., starch). Modified natural polymers are the result of a chemical reaction or modification to a natural polymer (i.e., carboxymethyl starch). Synthetic polymers are chemically reacted monomers [i.e., partially hydrolyzed polyacrylamides (PHPA's)]. The primary benefits of modified and synthetic polymers over natural polymers are increased temperature stability and contamination resistance. A general understanding of polymer classification and knowledge of the strengths, weaknesses, molecular weight, and functionality can facilitate selection and treatment strategy for polymers. Performance Characteristics The following performance characteristics desirable in a drilling fluid are selected from a list of advantages of oil-based drilling fluids and will be used to compare the performances of polymers and oil-based drilling fluids.Thermal stability.Formation stability.Protection of production zone.Lubricity and torque/drag reduction."Drillability."Environmental compatibility.Stuck-pipe prevention.Corrosion protection.Resistance to contamination. Thermal Stability. Synthetic polymer chemistry has probably made its most significant contribution to the drilling industry in high-temperature/high-pressure applications. During the deep-gas/high-bottomhole-temperature (BHT) drilling of the 1970's and 1980's, oil muds prevailed. During the late 1980's and early 1990's, numerous synthetic polymers proved technically capable and cost-effective at high BHT's and pressures. Synthetic polymers specifically formulated for deflocculating, fluid-loss control, and gel inhibition at high temperature proved to have wide utility. In 1989, Elsen et al. reported the use of a lime-based fluid at densities exceeding 18.0 lbm/gal with calculated BHT's above 350#F. Using limemuds at these hostile conditions would have been impossible without natural, modified, and synthetic polymers. Polymers used in this challenging environment included lignite, starch, polyanionic cellulose (PAC), polyanionic lignon, polymer-grafted lignosulfonate, modified polyacrylate terpolymer, and vinylamide/vinyl sulfonate copolymer. Numerous water-based systems incorporating various polymers have been used successfully and economically above 400 F with densities ranging from 15.0 to 18.0 lbm/gal. Successful completion of these wells with water-based polymers requires prespud planning and laboratory optimization specific to the drilling objective. These prerequisites must not be compromised. Special programs must be in place with wellsite laboratory equipment and laboratory confirmation for this technology to be applied successfully. Formation Stability. Various developments in the late 1980's and early1990's focused on improving formation stability by increasing the concentration of shale-inhibiting additives or by combining polymer additives that inhibit reactive shales. Preventing the hydration of swelling and/or reactive shales with water-based systems became the technical challenge of the drilling-fluid industry. A long list of polymers and polymer enhancers were thrust on the industry. Examples are saturated salt/PHPA, polyalcohol, polyglycol, cloud-point polyols, polyglycerine, cationic polymers, cationic starch, carboxymethyl starch, cationic PHPA, black liquids, black powders, potassiumpolyacrylates, potassium cellulosic polymers, polyamino acids, MMH, MMS, and methyl glucoside. Cationic polymer systems received increased attention in the early 1990's.The industry saw a major operator and a major service company introduce and promote cationic chemistry as a replacement for oil-based muds. The reviews of these systems were mixed. While some reports indicate the success of these systems, more field experience is needed to determine long-termapplicability. P. 691^

12 - Hydrogel- and aerogel-based composites: Biodegradable hydrogel and aerogel polymer blend-based composites

17 - Fabrication of Tissue Engineering Scaffolds

Minimally-invasive monitoring of regeneration in diseased tissue is an important aspect of stem cell therapy. Magnetic resonance imaging (MRI) based tracking of cells labelled with ferumoxides has the potential for non-invasive in vivo detection and longitudinal assessment of implanted cells. Cells labelled with ferumoxides appear as hypointense regions on MR images and thus can be distinguished from the surroundings. Application of this methodology to intervertebral disc degeneration (IVD), and detection of labelled cells implanted into the disc for tissue regeneration was examined. Mesenchymal stem cells labelled with a ferumoxide contrast agent were imaged in vitro to quantitatively characterize the signal intensity loss using MRI relaxation parameters (T1, T2, and T2*). To determine whether labelled cells could be detected within scaffolds suitable for implantation, labelled cells were seeded within both natural and synthetic polymers and imaged using MRI. Labelled cells were loaded within poly(ethylene glycol) hydrogels and imaged in vitro using both MRI and confocal microscopy. Labelled cells were also loaded into fibrin gels, and detected ex vivo within rat IVDs using MRI. Lastly, the effect of ferumoxide labelling on cell viability was investigated. Quantitatively, labelled cells demonstrate the greatest signal intensity loss and contrast on T2*-weighted images. Labelled cells can be detected in both synthetic and natural polymers, and can be distinguished from the native tissue environment of the rat IVD. Finally, labelling does not significantly impair cell viability. Consequently, this technique shows promise as a potential method for in vivo longitudinal tracking of stem cell based regeneration of the IVD.