Chitosan/starch fibers and their properties for drug controlled release

Role of Polymer Concentration on the Release Rates of Proteins from Single- and Double-Network Hydrogels

Controlled delivery of proteins has immense potential for the treatment of various human diseases, but effective strategies for their delivery are required before this potential can be fully realized. Recent research has identified hydrogels as a promising option for the controlled delivery of therapeutic proteins, owing to their ability to respond to diverse chemical and biological stimuli, as well as their customizable properties that allow for desired delivery rates. This study utilized alginate and chitosan as model polymers to investigate the effects of hydrogel properties on protein release rates. The results demonstrated that polymer properties, concentration, and crosslinking density, as well as their responses to pH, can be tailored to regulate protein release rates. The study also revealed that hydrogels may be combined to create double-network hydrogels to provide an additional metric to control protein release rates. Furthermore, the hydrogel scaffolds were also found to preserve the long-term function and structure of encapsulated proteins before their release from the hydrogels. In conclusion, this research demonstrates the significance of integrating porosity and response to stimuli as orthogonal control parameters when designing hydrogel-based scaffolds for therapeutic protein release.

Nano-hybrid electrospun non-woven mats made of wool keratin and hydrotalcites as potential bio-active wound dressings

In this work, nano-hybrid electrospun non-woven mats made of wool keratin combined with diclofenac loaded hydrotalcites (HTD) were prepared and characterized as potential drug delivery systems and scaffolds for fibroblast cell growth. Nano-hybrid electrospun non-woven mats showed a good adaptability to wet skin, effortlessly conforming to the three-dimensional topography of the tissue. Nanosized HTD exercised an overall reinforcing action on the electrospun non-woven mats since the nanohybrid samples displayed a reduced swelling ratio and a slower degradation profile compared to keratin-based nanofiber non-woven mats containing free diclofenac, without negative effects on drug release. The cell viability test indicated a decreased toxicity of the drug when loaded into nanofibers and confirmed the biocompatibility of keratin/HTD electrospun non-woven mats; moreover, a controlled diclofenac release within the first 24 hours does not compromise the fibroblast cell growth in a significant manner.

Treatment of neurodegenerative disorders through the blood-brain barrier using nanocarriers

Neurodegenerative diseases refer to disorders of the central nervous system (CNS) that are caused by neuronal degradations, dysfunctions, or death. Alzheimer's disease, Parkinson's disease, and Huntington's disease (APHD) are regarded as the three major neurodegenerative diseases. There is a vast body of literature on the causes and treatments of these neurodegenerative diseases. However, the main obstacle in developing an effective treatment strategy is the permeability of the treatment components at the blood-brain barrier (BBB). Several strategies have been developed to improve this obstruction. For example, nanomaterials facilitate drug delivery to the BBB due to their size. They have been used widely in nanomedicine and as nanoprobes for diagnosis purposes among others in neuroscience. Nanomaterials in different forms, such as nanoparticles, nanoemulsions, solid lipid nanoparticles (SLN), and liposomes, have been used to treat neurodegenerative diseases. This review will cover the basic concepts and applications of nanomaterials in the therapy of APHD.

Chitosan-based nanoparticles as drug delivery systems: a review on two decades of research

Chitosan (CS) is one of the most functional natural biopolymer widely used in the pharmaceutical field due to its biocompatibility and biodegradability. These privileges lead to its application in the synthesis of nanoparticles for the drug during the last two decades. This article gives rise to a general review of the different chitosan nanoparticles (CSNPs) preparation techniques: Ionic gelation, emulsion cross-linking, spray-drying, emulsion-droplet coalescence method, nanoprecipitation, reverse micellar method, desolvation method, modified ionic gelation with radial polymerisation and emulsion solvent diffusion, from the point of view of the methodological and mechanistic aspects involved. The physicochemical behaviour of CSNPs including drug loading, drug release, particles size, zeta potential and stability are briefly discussed. This review also directs to bring an outline of the major applications of CSNPs in drug delivery according to drug and route of administration. Finally, derivatives of CSNPs and CS nano-complexes are also discussed.

Controlled release for crop and wood protection: Recent progress toward sustainable and safe nanostructured biocidal systems

We review biocide delivery systems (BDS), which are designed to deter or control harmful organisms that damage agricultural crops, forests and forest products. This is a timely topic, given the growing socio-economical concerns that have motivated major developments in sustainable BDS. Associated designs aim at improving or replacing traditional systems, which often consist of biocides with extreme behavior as far as their solubility in water. This includes those that compromise or pollute soil and water (highly soluble or volatile biocides) or those that present low bioavailability (poorly soluble biocides). Major breakthroughs are sought to mitigate or eliminate consequential environmental and health impacts in agriculture and silviculture. Here, we consider the most important BDS vehicles or carriers, their synthesis, the environmental impact of their constituents and interactions with the active components together with the factors that affect their rates of release such as environmental factors and interaction of BDS with the crops or forest products. We put in perspective the state-of-the-art nanostructured carriers for controlled release, which need to address many of the challenges that exist in the application of BDS.

Development of chitosan based extended-release antioxidant films by control of fabrication variables

In this study, mechanical, optical and permeability to water vapor of chitosan containing α-tocopherol film as the function of preparation conditions including concentration of emulsifier and speed of homogenization have investigated. In addition, the effect of above mentioned variables and presence of ethanol as co-surfactant on the release rate of α-tocopherol from chitosan film to fatty food simulant (ethanol 95%) were investigated. Fourier transform infrared spectroscopy and differential scanning calorimetry were employed to analyze the structural and thermal properties of the films. Results showed that the incorporation of α-tocopherol and preparation conditions affected the physical and mechanical properties of the chitosan films. Obtained results indicated that increasing the concentration of Tween 80 increased the release rate of α-tocopherol in the most studied films. Increasing the stirring speed of homogenization and the presence of ethanol considerably decreased the release rate of α-tocopherol at the most film samples. The lowest amount of released antioxidant was 8.6-10% of total incorporated α-tocopherol at the first stages and is obtained when ethanol used during preparation of film forming solution. Our results indicated that the release rate of α-tocopherol could be controlled by changing the stirring speed of homogenization and especially ethanol presence, considerably.

Recent advances in liposome surface modification for oral drug delivery

Oral delivery via the gastrointestinal (GI) tract is the dominant route for drug administration. Orally delivered liposomal carriers can enhance drug solubility and protect the encapsulated theraputic agents from the extreme conditions found in the GI tract. Liposomes, with their fluid lipid bilayer membrane and their nanoscale size, can significantly improve oral absorption. Unfortunately, the clinical applications of conventional liposomes have been hindered due to their poor stability and availability under the harsh conditions typically presented in the GI tract. To overcome this problem, the surface modification of liposomes has been investigated. Although liposome surface modification has been extensively studied for oral drug delivery, no review exists so far that adequately covers this topic. The purpose of this paper is to summarize and critically analyze emerging trends in liposome surface modification for oral drug delivery.

Chitosan-starch beads prepared by ionotropic gelation as potential matrices for controlled release of fertilizers

The present study examines the agrochemical application of macrospheres prepared with chitosan and chitosan-starch blends by an easy dripping technique, using a sodium tripolyphosphate aqueous solution as the crosslinking agent. These biopolymers form hydrogels that could be a viable alternative method to obtain controlled-release fertilizers (CRFs). Three different concentrations (ranging from 20 to 100wt/wt% of chitosan) and two crosslinking times (2 or 4h) were used. The resulting polymeric matrices were examined by scanning electron microscopy coupled with energy dispersive X-ray, X-ray diffraction, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance, thermogravimetric analysis and differential scanning calorimetry. Ionotropic gelation and neutralization induced the formation of the macrospheres. The crosslinking time and the composition of the polymeric hydrogel controlled the crosslinking degree, the swelling behavior and the fertilizer loading capability. Potassium nitrate-loaded beads were shown to be useful as a controlled-release fertilizer. After 14days of continuous release into distilled water, the cumulative concentration in the release medium reached between 70 and 93% of the initially loaded salt, depending on the matrix used. The prepared beads showed properties that make them suitable for use in the agrochemical industry as CRFs.

Anticancer and anti-inflammatory properties of chitin and chitosan oligosaccharides

Previous reports indicate that N-acetyl-d-glucosamine oligomers (chitin oligosaccharide; NACOS) and d-glucosamine oligomers (chitosan oligosaccharide; COS) have various biological activities, especially against cancer and inflammation. In this review, we have summarized the findings of previous investigations that have focused on anticancer or anti-inflammatory properties of NACOS and COS. Moreover, we have introduced recent evaluation of NACOS and COS as functional foods against cancer and inflammatory disease.

Chitin and chitosan nanofibers: preparation and chemical modifications

Chitin nanofibers are prepared from the exoskeletons of crabs and prawns, squid pens and mushrooms by a simple mechanical treatment after a series of purification steps. The nanofibers have fine nanofiber networks with a uniform width of approximately 10 nm. The method used for chitin-nanofiber isolation is also successfully applied to the cell walls of mushrooms. Commercial chitin and chitosan powders are also easily converted into nanofibers by mechanical treatment, since these powders consist of nanofiber aggregates. Grinders and high-pressure waterjet systems are effective for disintegrating chitin into nanofibers. Acidic conditions are the key factor to facilitate mechanical fibrillation. Surface modification is an effective way to change the surface property and to endow nanofiber surface with other properties. Several modifications to the chitin NF surface are achieved, including acetylation, deacetylation, phthaloylation, naphthaloylation, maleylation, chlorination, TEMPO-mediated oxidation, and graft polymerization. Those derivatives and their properties are characterized.

Emerging chitin and chitosan nanofibrous materials for biomedical applications

Over the past several decades, we have witnessed significant progress in chitosan and chitin based nanostructured materials. The nanofibers from chitin and chitosan with appealing physical and biological features have attracted intense attention due to their excellent biological properties related to biodegradability, biocompatibility, antibacterial activity, low immunogenicity and wound healing capacity. Various methods, such as electrospinning, self-assembly, phase separation, mechanical treatment, printing, ultrasonication and chemical treatment were employed to prepare chitin and chitosan nanofibers. These nanofibrous materials have tremendous potential to be used as drug delivery systems, tissue engineering scaffolds, wound dressing materials, antimicrobial agents, and biosensors. This review article discusses the most recent progress in the preparation and application of chitin and chitosan based nanofibrous materials in biomedical fields.

3-dimensional (3D) fabricated polymer based drug delivery systems

Drug delivery from 3-dimensional (3D) structures is a rapidly growing area of research. It is essential to achieve structures wherein drug stability is ensured, the drug loading capacity is appropriate and the desired controlled release profile can be attained. Attention must also be paid to the development of appropriate fabrication machinery that allows 3D drug delivery systems (DDS) to be produced in a simple, reliable and reproducible manner. The range of fabrication methods currently being used to form 3D DDSs include electrospinning (solution and melt), wet-spinning and printing (3-dimensional). The use of these techniques enables production of DDSs from the macro-scale down to the nano-scale. This article reviews progress in these fabrication techniques to form DDSs that possess desirable drug delivery kinetics for a wide range of applications.

Preparation and Characterization of Starch Nanoparticles for Controlled Release of Curcumin

Curcumin was loaded onto starch nanoparticles by usingin situnanoprecipitation method and water-in-oil microemulsion system. Curcumin loaded starch nanoparticles exhibited enhanced solubility in aqueous solution as compared to free curcumin. Effects of formulation parameters such as types of reaction medium, types of surfactant, surfactant concentrations, oil/ethanol ratios, loading time, and initial curcumin concentration were found to affect the particle size and loading efficiency (LF) of the curcumin loaded starch nanoparticles. Under optimum conditions, curcumin loaded starch nanoparticles with mean particles size of 87 nm and maximum loading efficiency of 78% were achieved. Curcumin was observed to release out from starch nanoparticles in a sustained way under physiological pH over a period of 10 days.

Electrical Signal Guided Ibuprofen Release from Electrodeposited Chitosan Hydrogel

Electrical signal guided drug release from conductive surface provides a simple and straightforward way for advanced drug delivery. In this study, we investigated the ibuprofen release from electrodeposited chitosan hydrogel by applying electrical signals. Specifically, chitosan hydrogel was electrodeposited on titanium plate and used as a matrix for ibuprofen load and release. The release of ibuprofen from the chitosan hydrogel on titanium plate was pH sensitive. By applying a positive or negative electrical potential, the release rate of ibuprofen from the electrodeposited chitosan can be facilely controlled. Thus, coupling chitosan electrodeposition and electrical signal control spurs new possibilities for biopolymeric coating and drug elution on conductive implants.

Salicylic acid and some of its derivatives as antibacterial agents for viscose fabric

Salicylic acid and three of its derivatives were used to provide antibacterial properties to viscose fabrics. The four bactericides used were bonded to the viscose fabrics using epichlorohydrin or polymer binders. Optimization of the salicylic acid and its derivatives as well as the concentration of polymers was reported. The ability of the polymer binders to attract and bind the four bactericides was observed. The overall results show that the antibacterial reactivity of salicylic acid and its derivatives are in the following order 5-bromosalicylic acid>salicylic acid>5-chlorosalicylic acid>4-chlorosalicylic acid. Using epichlorohydrin as a binding agent, unfortunately, inhibits the bactericidal activity of the four bactericides. The FTIR study concludes that the reaction between salicylic acid as well as its derivatives with epichlorohydrin takes place through the phenolic group of the acids. The unexpected deterioration in the bactericidal properties of salicylic acid and its derivatives as a result of the treatment with epichlorohydrin could be due to the nature of interaction between the epichlorohydrin molecule and the acids molecules. PVP and PU show superior ability to sustain the four bactericides used even after 10 washing cycles.

Hybrid hydroxyapatite nanoparticle colloidal gels are injectable fillers for bone tissue engineering

Injectable bone fillers have emerged as an alternative to the invasive surgery often required to treat bone defects. Current bone fillers may benefit from improvements in dynamic properties such as shear thinning during injection and recovery of material stiffness after placement. Negatively charged inorganic hydroxyapatite (HAp) nanoparticles (NPs) were assembled with positively charged organic poly(d,l-lactic-co-glycolic acid) (PLGA) NPs to create a cohesive colloidal gel. This material is held together by electrostatic forces that may be disrupted by shear to facilitate extrusion, molding, or injection. Scanning electron micrographs of the dried colloidal gels showed a well-organized, three-dimensional porous structure. Rheology tests revealed that certain colloidal gels could recover after being sheared. Human umbilical cord mesenchymal stem cells were also highly viable when seeded on the colloidal gels. HAp/PLGA NP colloidal gels offer an attractive scheme for injectable filling and regeneration of bone tissue.

Development of chitosan-tripolyphosphate non-woven fibrous scaffolds for tissue engineering application

The fibrous scaffolds are promising for tissue engineering applications because of their close structural resemblance with native extracellular matrix. Additionally, the chemical composition of scaffold is also an important consideration as they have significant influences on modulating cell attachment, morphology and function. In this study, chitosan-tripolyphosphate (TPP) non-woven fibrous scaffolds were prepared through wetspinning process. Interestingly, at physiological pH these scaffolds release phosphate ions, which have significant influences on cellular function. For the first time, cell viability in presence of varying concentration of sodium TPP solution was analyzed and correlated with the phosphate release from the scaffolds during 30 days incubation period. In vitro degradation of the chitosan-TPP scaffolds was higher than chitosan scaffolds, which may be due to decrease in crystallinity as a result of instantaneous ionic cross-linking during fiber formation. The scaffolds with highly interconnected porous structure present a remarkable cytocompatibility for cell growing, and show a great potential for tissue engineering applications.

In vivo chondrocyte and transforming growth factor-β1 delivery using the thermosensitive chitosan/starch/β-glycerol phosphate hydrogel

In present study, the chitosan/starch/β-glycerol phosphate hydrogel was investigated as an effective carrier for chondrocytes and delivery of transforming growth factor-β1. In vitro study indicated that transforming growth factor-β1 was released sustainably for 14 days with its biological activity to stimulate chondrocyte functions, as indicated by the strong expression of type II collagen protein. Subcutaneous implantation to rats revealed the strong expressions of type II collagen and aggrecan messenger ribonucleic acids, and also type II collagen protein was observed in the hydrogel in combination with transforming growth factor-β1 within 2 weeks. Our collective results showed the potential of chitosan/starch/β-glycerol phosphate hydrogel for effective delivery of chondrocytes and transforming growth factor-β1, and preserve chondrocytes’ phenotype and functions in vitro.

Development of chitosan-tripolyphosphate fibers through pH dependent ionotropic gelation

Incorporation of phosphate groups into a material may be of particular interest as they act as templates for hydroxyapatite growth through complexation with Ca(2+) and thus improve the osteoconduction property. The phosphate groups can be incorporated into chitosan through ionotropic gelation with tripolyphosphate (TPP). Interestingly, the ion pairs formed through negatively charged phosphate groups with protonated amine functionality of chitosan in ionotropic gelation are expected to provide chitosan with an amphoteric character, which may facilitate protein adhesion following enhanced attachment of anchorage dependant cells than chitosan, which shows poor cell adhesion properties. In this study, chitosan-tripolyphosphate (TPP) fibers with varying phosphate contents were prepared through wet spinning in STPP baths of different pH. Gelation kinetics and gel strength of chitosan with STPP solutions of three different pH were evaluated and compared with that of NaOH solution for evaluation of their influence on nature of gelation. The solution pH of STPP baths was found to have significant control on the extent of ionic cross-linking and physico-chemical properties of the fibers. Moreover, this kinetically driven ionotropic gelation of chitosan by TPP results in low degree of crystallinity of chitosan-TPP fibers and consequently their lower thermal stability than chitosan fibers.

PLGA-chitosan/PLGA-alginate nanoparticle blends as biodegradable colloidal gels for seeding human umbilical cord mesenchymal stem cells

The natural polymers chitosan and alginate represent an attractive material choice for biodegradable inplants. These were used as coating materials to make positively and negatively charged PLGA nanoparticles, respectively. After blending at total solids concentration >10% wt/vol, these oppositely charged nanoparticles yielded a cohesive colloidal gel. Electrostatic forces between oppositely charged nanoparticles produced a stable 3D porous network that may be extruded or molded to the desired shape. This high concentration colloidal system demonstrated shear-thinning behavior due to the disruption of interparticle interactions. Once the external force was removed, the cohesive property of the colloidal gel was recovered. Scanning electron micrographs of dried colloidal networks revealed an organized, 3D microporous structure. Rheological studies were employed to probe the differences in plasticity and shear sensitivity of colloidal gels. Viability tests of hUCMSCs seeded on the colloidal gels also demonstrated the negligible cytotoxicity of the materials. All the results indicated the potential application of the biodegradable colloidal gels as an injectable scaffold in tissue engineering and drug release.

Impact of biological agents and tissue engineering approaches on the treatment of rheumatic diseases

The treatment of rheumatic diseases has been the focus of many clinical studies aiming to achieve the best combination of drugs for symptom reduction. Although improved understanding of the pathophysiology of rheumatic diseases has led to the identification of effective therapeutic strategies, its cure remains unknown. Biological agents are a breakthrough in the treatment of these diseases. They proved to be more effective than the other conventional therapies in refractory inflammatory rheumatic diseases. Among them, tumor necrosis factor inhibitors are widely used, namely Etanercept, Infliximab, or Adalimumab, alone or in combination with disease-modifying antirheumatic drugs. Nevertheless, severe adverse effects have been detected in patients with history of recurrent infections, including cardiac failure or malignancy. Currently, most of the available therapies for rheumatic diseases do not have sufficient tissue specificity. Consequently, high drug doses must be administrated systemically, leading to adverse side effects associated with its possible toxicity. Drug delivery systems, by its targeted nature, are excellent solutions to overcome this problem. In this review, we will describe the state-of-the-art in clinical studies on the treatment of rheumatic diseases, emphasizing the use of biological agents and target drug delivery systems. Some alternative novel strategies of regenerative medicine and its implications for rheumatic diseases will also be discussed.

Polyacrylonitrile fibers efficiently loaded with tamoxifen citrate using wet-spinning from co-dissolving solution

Tamoxifen citrate (TAM)-loaded polyacrylonitrile (PAN) fibers were prepared using an improved wet-spinning technique. TAM was used as a model drug to evaluate the potential application of the loaded fiber system for drug delivery. PAN was first homogeneously dissolved in the N,N-dimethylacetamide (DMAc) solution containing TAM and then the co-dissolving solution was solidified to prepare the fibers using a wet-spinning method. Chemical, morphological and mechanical property characterizations were carried out, as well as the studies of the drug release properties. TAM was successfully encapsulated into a monofilament fiber, and this system was stable in terms of high loading capacity and effectiveness in release. The diameter of drug-loaded fiber was in the range of 40-60 microm. The best values of the tensile strength at 2.968 cN/dtex and breaking elongation at 14.9% of drug-loaded fibers were obtained when the drug loading content was 23.1 wt.%. These characteristics were suitable for the weaving process. The in vitro release experiment indicated that constant drug release from the fiber was observed for a long duration of time. Kinetic studies demonstrated that the system followed the Higuchi kinetics. These findings demonstrate that controlled release of drugs from PAN fibers could be potentially useful in drug delivery systems.