6 - Nanoengineered polymeric biomaterials for drug delivery system

Advances in Drug Delivery

Plant proteins show good potential for medical applications but offer considerable challenges in fabricating biomaterials. Despite substantial efforts, especially in the last decade, to develop polymeric biomaterials, there are no polymers that are ideally suited for tissue engineering, drug delivery and other medical applications. Therefore, the quest to find new sources for biomaterials continues. Natural proteins such as collagen and silk, carbohydrates such as chitosan and cellulose and synthetic biopolymers such as poly (lactic acid) have been extensively studied for potential medical applications. Biotechnology and nanotechnology have also been widely adopted to develop regenerated and recombinant polymers for medical applications. The advent of nanotechnology and its many advantages for medical applications have led to the development of nanofibers and nanoparticles from both the natural and synthetic polymers for tissue engineering, controlled release and other medical applications. However, both natural and synthetic polymers currently available have many limitations that restrict their use for medical applications. Biomaterials developed from natural polymers do not have the desired mechanical properties for medical applications. For instance, scaffolds developed from collagen have poor hydrolytic stability and efforts to crosslink and improve the properties have not been successful to provide cytocompatible biomaterials. Although silk has excellent mechanical properties and biocompatibility, silk has slow degradation rates and it is difficult to dissolve and process silk into various types of biomaterials. Biomaterials developed from most synthetic polymers have the biocompatibility and mechanical properties but their degradation into toxic substances in the body is a cause for concern. Similarly, metal and ceramic based biomaterials do not have the desired degradability and are difficult to process into different forms of biomaterials.

Ancient fibrous biomaterials from silkworm protein fibroin and spider silk blends: Biomechanical patterns

Microparticle delivery system is accepted as are reliable. Mean to delivery the drug to the target site with specificity,. The drug should be delivered to specific target site at a rate and concentration that provides optimum therapeutic efficacy and reducing the side effect to minimum. Microspheres are empty spherical particles, the particle size is less than 200 mm. Microspheres are free flowing powder consisting of natural and synthetic polymers. They have the potential controlled release drug. Polymers are the most important things of pharmaceutical drug delivery. There are many kind of polymers which varying the properties available those days for use in different pharmaceutical applications. Polymers use in the preparation of microspheres is the synthetic and natural polymers. Synthetic polymers are acrolein, poly anhydrides, methyl meth acrylate, lactides, and glycosides. Natural polymers are albumin, gelatin, collagen, agarose, chitosan, carragenene. Microspheres are the free flowing powders consist of protein and synthetic polymers having a particle size ranging from 1 ? 1000 micrometer. Microspheres are prepared by several techniques but the choice of method depends upon the drug. The polymers used and duration of action required. The evaluation parameters of microspheres are micromeritic properties particle size and shape, swelling index, tapped density, drug loading efficiency. In coming days by combining numerous other sceniorio, we will find the microspheres in novel drug delivery. Specifically in disease cell sorting diagnostics, gene and genetic materials, safe targeted and effective in vivo delivery and supplements a tiny interpretation of diseased organ and tissue in the body. Keywords: Microencapsulation, novel drug delivery, synthetic and natural polymers, duration of action.

Electrospinning is a process where polymeric solutions are extruded through a charged electrical field consisting of + vely and – vely charged source/collector. Fibers in the nano- to micrometer scale are produced by controlling the distance between needle and collector and voltage and other parameters during electrospinning. Electrospun fibers are preferred for a variety of applications due to their high surface area, ability to develop fibrous matrices with desired porosity and pore size, and comparatively easy biodegradability. Due to these advantages, electrospun fibers have been considered suitable as tissue engineering scaffolds and other medical applications, reinforcement for composites, filters for biotechnological applications, protective clothing and smart textiles, and in energy and electronic applications such as batteries/cell and capacitors, sensors, and catalysts [14Bra]. Due to their wide acceptability and unique properties, attempts have been made to develop electrospun fibers from almost every possible raw material. Reports are available on producing electrospun fibers from polysaccharides such as cellulose and chitosan, proteins such as silk fibroin and gelatin, synthetic polymers such as polypropylene and poly(lactic acid), and even from metals such as TiO2 [08For]. This part provides an overview of the biopolymers including polysaccharides, proteins, and synthetic polymers that have been used to develop electrospun fibers. Since there is a massive amount of literature in developing electrospun fibers, especially from synthetic polymers, our focus in this part is to only cover electrospun fibers produced from polysaccharides and proteins and synthetic biopolymers such as poly(lactic acid) and poly(ethylene glycol) that are derived from renewable resources.

Polymer blends and composites from renewable resources

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

Marine and terrestrial humic acids are thought to differ in structural composition owing to differences in precursors and formation pathways. It has been proposed that marine humic acids are formed by the polymerization of sugars and amino acids (the melanoidin pathway) while terrestrial humic acids result primarily from the condensation of lignin-derived phenols and amino acids. In this study, four marine and three terrestrial humic acids have been isolated, and a series of polymers have been made by the reaction of either glucose or catechol with alanine or ammonia. Chemical and spectroscopic measurements of the natural and synthetic polymers have been made, including elemental analysis, carbon isotope ratios and IR, UV-visible, UV-fluorescence, and ESR scans. In additi n, degradative analyses of marine and terrestrial humic acids together with the synthetic polymers have been performed to determine (1) if characteristic structural differences exist between marine and terrestrial humic acids and (2) if similarities between the degradative products of synthetic and natural polymers reflect biologic precursors and reaction pathways. End_of_Article - Last_Page 704------------

Most commercialized wound dressings are polymer-based. Synthetic and natural polymers have been utilized widely for the development of wound dressings. However, the use of natural polymers is limited by their poor mechanical properties, resulting in their combination with synthetic polymers and other materials to enhance their mechanical properties. Natural polymers are mostly affordable, biocompatible, and biodegradable with promising antimicrobial activity. They have been further tailored into unique hybrid wound dressings when combined with synthetic polymers and selected biomaterials. Some important features required in an ideal wound dressing include the capability to prevent bacteria invasion, reduce odor, absorb exudates, be comfortable, facilitate easy application and removal as well as frequent changing, prevent further skin tear and irritation when applied or removed, and provide a moist environment and soothing effect, be permeable to gases, etc. The efficacy of polymers in the design of wound dressings cannot be overemphasized. This review article reports the efficacy of wound dressings prepared from a combination of synthetic and natural polymers.

1 - Introduction to polymeric nanomaterials

This study aims to produce composite nanofibers from polylactic acid (PLA) and silk fibroin (SF) with mechanical properties similar to that of a native meniscus. SF is a natural protein, well known for its good biocompatibility and biodegradability but it has poor mechanical properties compared to synthetic polymers. SF contains proteins which can promote cell adhesion and cell proliferation required for a tissue engineering scaffold. PLA is a popular material that is widely used in tissue engineering. It provides high mechanical properties but lacks bioactivity and cell affinity. Thus, a PLA/SF composite scaffold can improve these drawbacks. In this study, PLA/SF nanofibers were fabricated using an electrospinning process at various PLA and SF ratios (PLA: SF 100:0, 75:25, 50:50, and 25:75). The SF content in the emulsion dominated the fiber diameter, fiber arrangement and processibility of nanofibrous scaffold. With increasing SF content, the %elongation at break of PLA/SF scaffold increased but Young’s modulus decreased. The wettability of electrospun PLA was increased with an increase in SF content.

Electrospinning is one of the techniques to produce structured polymeric fibers in the micro or nano scale and to generate novel materials for biomedical proposes. Electrospinning versatility provides fibers that could support different surgical and rehabilitation treatments. However, its diversity in equipment assembly, polymeric materials, and functional molecules to be incorporated in fibers result in profusion of recent biomaterials that are not fully explored, even though the recognized relevance of the technique. The present article describes the main electrospun polymeric materials used in oral applications, and the main aspects and parameters of the technique. Natural and synthetic polymers, blends, and composites were identified from the available literature and recent developments. Main applications of electrospun fibers were focused on drug delivery systems, tissue regeneration, and material reinforcement or modification, although studies require further investigation in order to enable direct use in human. Current and potential usages as biomaterials for oral applications must motivate the development in the use of electrospinning as an efficient method to produce highly innovative biomaterials, over the next few years. Impact statement Nanotechnology is a challenge for many researchers that look for obtaining different materials behaviors by modifying characteristics at a very low scale. Thus, the production of nanostructured materials represents a very important field in bioengineering, in which the electrospinning technique appears as a suitable alternative. This review discusses and provides further explanation on this versatile technique to produce novel polymeric biomaterials for oral applications. The use of electrospun fibers is incipient in oral areas, mainly because of the unfamiliarity with the technique. Provided disclosure, possibilities and state of the art are aimed at supporting interested researchers to better choose proper materials, understand, and design new experiments. This work seeks to encourage many other researchers-Dentists, Biologists, Engineers, Pharmacists-to develop innovative materials from different polymers. We highlight synthetic and natural polymers as trends in treatments to motivate an advance in the worldwide discussion and exploration of this interdisciplinary field.

The aim of the proposed research work was to develop a unique dual-compartment capsule dosage form of ciprofloxacin hydrochloride (CHL) which is well-known to have short elimination half-life and narrow absorption window. Formulated dual-compartment capsules were evaluated for its suitability for stomach specific drug delivery by employing different polymers such as Guar gum, Xanthan gum. Formulations were assessed for interaction studies, in vitro buoyancy, effect of polymer concentration on drug release and release kinetics. Experimental results demonstrated that natural polymers can be effectively exercised to formulate capsule dosage form for improved gastro retention and sustained drug release; which may be better and economic alternative for synthetic polymers.

Polymer contamination with the advent of fast industrialization has become one of the serious threat to the natural environment. Due to lack of proper knowledge, poor waste management practice and unavailability of potential microbial strains, preference toward the biodegradable manmade and natural polymers. The prevalent occurrence of synthetic polymers is related to industrialization and domestic practices which affect the marine and terrestrial ecosystems. Scientific approaches exploited for polymer degradation include physical, chemical and biological treatments. Among them, biodegradation serves as eco-friendly approach to remediate polluted environment using living organisms. In this chapter biodegradation of natural (cellulose, hemicelluloses and lignin), synthetic (polyurethane, polyethylene succinate, polycaprolactone, polyvinyl alcohol and polyethylene) polymers and associated factors that influence the polymer biodegradation process have been discussed.

Chemical enhanced oil recovery (EOR) processes are usually used as additives for hydrocarbon production due to its simplicity and relatively reasonable additional production costs. Polymer flooding uses polymer solutions to increase oil recovery by decreasing the water/oil mobility ratio by increasing the viscosity of the displacing water. The commonly used synthetic water-soluble polymer in EOR application is partially hydrolyzed polyacrylamide (HPAM). However, synthetic polymers in general are not attractive because of high cost, environmental concerns, limitation in high temperature, and high-salinity environment. Guar gum is an environmentally friendly natural water-soluble polymer available in large quantities in many countries and widely used in various applications in the oil and gas industry especially in drilling fluids and hydraulic fracturing operations; however, very limited studies investigated on guar as a polymer for EOR and no any study investigated on its uses in high-temperature and high -salinity reservoirs. The objective of this study is to confirm the use of guar gum as a natural polymer for EOR applications in sandstone reservoirs and investigate its applicability for high-temperature and high-salinity reservoirs. The study experimentally investigated rheological characteristics of a natural polymer obtained from guar gum with consideration of high temperature (up to 210 °F) and high salinity (up to 20% NaCl) and tested the guar solution as EOR polymer. The results of this study show that the guar solution can be used as an environmentally friendly polymer to enhance oil recovery. Based on the results, it can be concluded that guar gum shows shear-thinning behavior and strongly susceptible to microbial degradation but also shows a very good properties stability in high temperature and salinity, where in low shear rate case, about 100 cp viscosity can be achieved at 210 °F for polymer prepared in deionized water. Guar polymer shows good viscosity in the presence of 20% NaCl where the viscosity is acceptable for temperature less than 190 °F. Also, the flooding experiment shows that the recovery factor can be increased by 16%.