Ionically cross-linked chitosan–halloysite composite microparticles for sustained drug release

Thermoresponsive chitosan copolymers embed with antifouling agent paeonol in chitosan(CS) microparticles were prepared and the release dynamics was studied at different temperature. Chitosan microparticles have been formed based on ionic gelation process of CS and sodium tripolyphosphate (TPP). Paeonol was incorporated into the CS microparticles with the size about 0.1 μm. The physicochemical structure of samples was analyzed by FTIR and scanning electron microscopy (SEM). We investigated the influence of sodium tripolyphosphate (TPP) and paeonol on Encapsulation efficiency. Increasing TPP concentration from 1 to 3 mg/ml increased encapsulation efficiency of paeonol from 63% to 92%. Increasing peaonol concentration from 1.0 to 3.0 mg/ml increased peaonol encapsulation efficiency from 72% to 85%.

Back Ground Chitosan as a natural polymer has been fabulated into a number of formulations such as films, hydrogels and particles based on its excellent properties such as biodegradable, biocompotable, bioadhesive, permeartion-enhancement, antibiotic, antitumor etc. properties. Among them, chitosan microparticles found a lot of applications in pharmaceutics such as vaccine delivery, mucosal delivery and gene delivery, etc. Down to the nanoscale, chitosan nanoparticles have more attractive properties more than that of chitosan microparticles, which further widen the applications of chitosan particles in biomedicine and biopharmaceutics. Objective of this Thesis This thesis is aimed to prepare chitosan micro or nanoparticles to delivery proteins. What are the questions this thesis attempted to solve? 1) What are the proper preparation conditions of chitosan micro or nanoparticles? 2) How does the pH value affect the formation and protein encapsulation of chitosan nanoparticles? 3) How to overcome the burst release of chitosan nanoparticles? 4) How to overcome the aggregation disadvantage in the contritional preparation process of TPP-gelated chitosan microparticles? 5) How to construct a composite particles system to realize the sustainable release of proteins? What are the methods used in this thesis? 1) ionotropic gelation method to prepare chitosan nanoparticles 2) Emulsification-coacervation (NaOH) method to prepare chitosan microparticles 3) a polyelectrolytes coacervation method to prepare chitosan-BSA complexes 4) a microemulsion involved emulsification-coalescence method to prepare TPP-gelated chitosan microparticles 5) a nanoparticles encapsulation method to prepare composite particles. Results and Conclutions 1) the effect of preparation parameters on the properties of chitosan nanoparticles: 1a) the concentration of chitosan has no siganificant effect on particles yield, positively associated with particles size, size distribution, positively associated with BSA encapsulation efficiency in a specific concentration range; 1b) the mass matio of chitosan to TPP negatively associated with particles yield, positively associated with particle size and size distribution, negatively associated with BSA encapsulation efficiency; 1c) the concentration of BSA has no significant effect on particles yield, particle size or size distribution, negatively associated with BSA encapsulation efficiency in a specific concentration range. 2) a chitosan polymer chain conformation related mechanism is proposed through the study of the effect of pH value on the formation and BSA encapsulation of chitosan nanoparticles. 3) the most homogeneous and smooth chitosan particles could be obtained at the parameters of: 2% (m/v) chitosan solution, 2/10 w/o volume ratio, 4% Span 85 as susfactant, 5 Krpm homogenization speed and 3 times addition of NaOH solution as a coacervation agent. The obtained particles have a mean diameter of 9.4±1.9 m. The BSA loading test found that dispersed particles only could be obtained below the BSA concentration of 0.5% under above mentioned parameters. 4) a noval polyelectrolytes complex formed by TPP and BSA is obtained attempted to solve the burst release effect of chitosan nanoparticles. 5) a microemulsion involved emulsification-coalescence method is used to overcome the aggregation problem of TPP-gelated chitosan microparticles. 6) a chitosan nanoparticles encapsulated PLA composite particles are successfully constructed. What is new in this thesis? 1) to study the formation mechanism and protein encapsulation of chitosan nanoparticles through the study of the effect of pH value on their properties and propose the role of chitosan polymer chain conformation during this process, 2) a noval TPP-BSA polyelectrolytes complex is obtained base on the purpose to overcome the burst release effect of chitosan nanoparticles, 3) apply emulsification-coalescence method in which a microemulsion of cross-linking agent-TPP is used to solve the aggregation problem of TPP-gelated chitosan microparticles, 4) propose a chitosan nanoparticles encapsulated PLA composite particles to control the release of proteins. Where is the study of this thesis in the field? 1) Chitosan nanoparticles have been extensively investigated in the past few years and the factors which can affect the properties of chitosan nanoparticles have been well documented as well. This thesis provides the evidence from a new side to understand the formation and protein encapsulation mechanisms of chitosan nanoparticles. 2) New and highly effective methods have been proposed by others to prepare protein loaded chitosan microparticles such as sieving and microfluidic methods which can reproduceably scale up the production of monodispersed chitosan microparticles. This thesis just solved a technique problem in the conventional preparation process of TPP-gelated chitosan microparticles. 3) The proposed TPP-BSA polyelectrolytes complex could be an alternative route to overcome the burst release effect of chitosan nanoparticles. 4) The proposed chitosan nanoparticles encapsulated PLA composite particles is one of the solutions among other composite particles proposed by others

The aim of this study was to scale-up and optimize the chitosan (CS) microparticles (MPs) from 1× batch (41–85 mg) to 4× batch (270–567 mg) to be used in bone regeneration. The MPs used in the present study were prepared by double emulsification technique using CS as a base material under physiologically friendly conditions throughout the process. Structural integrity of MPs was improved creating cross-links between amine groups in CS and phosphate groups in tripolyphosphate (TPP) which has been used as an ionic cross-linking agent. The cross-linking density was varied using different amounts of TPP to CS such as 0%, 8%, 32%, 64% and 110% (w/w). The CS MPs were approximately spherical in shape with a size of 30–50 µm according to scanning electron microscopy results. X-ray diffraction data revealed having TPP in the CS MPs. The evidence of ionic cross-links in the CS MPs was analyzed using Fourier Transform Infra Red. When we scaled-up the yield of MPs, we investigated that 64% TPP cross-linking density provided the best quality MPs. In addition, those MPs provided the yield from 75 mg to 310 mg when scaled up from 1× to 4× batch, respectively. The MPs developed have a great potential to be used as an injectable scaffold for bone regeneration including orthopedic and craniofacial applications using minimally invasive conditions compared with conventional three-dimensional scaffolds.

Composite microparticles of halloysite clay nanotubes bound by calcium carbonate

Halloysite nanotubes (HNTs) are fascinating carriers for the delivery of chemotherapy drugs. Surface modification of HNTs and their loading in polymer matrixes can create a delivery system with more controlled and sustained drug release. Taking this into account, in the present research, a drug delivery system was made by grafting a block copolymer of polyacrylic acid (PAA)/polyaniline (PANI) on HNT surface and incorporating copolymer-grafted HNTs into the polycaprolactone (PCL) fibers. For this purpose, PANI-b-PAA copolymer was first formed on HNT surface by grafting from strategy. Then, the copolymer-grafted HNTs and doxorubicin were loaded into PCL solution and the composite solution was processed by electrospinning. Preliminary evaluations confirmed the successful grafting of PANI-b-PAA copolymer onto HNTs. SEM and EDS analyses showed that drug loaded composite nanofibers have an average diameter of 396 nm and a uniform distribution of HNTs and doxorubicin. Drug release study revealed that composite nanofibers have less burst release and more sustained release than PCL nanofibers. Investigation of drug release mechanism by kinetics models corroborated that the drug release from composite nanofibers is mainly controlled by Fickian diffusion. Cell culture experiment verified that the composite nanofibers have higher cytotoxic effects and kill more tumor cells compared to PCL nanofibers. In summary, modifying the surface of HNT and incorporating it into PCL nanofibers can create a drug carrier with more sustained drug release and higher antitumor effects.

In vitro biocompatibility, antibacterial activity, and release behavior of halloysite nanotubes loaded with diclofenac sodium salt incorporated in electrospun soy protein isolate/hydroxyethyl cellulose nanofibers

In this study, chitosan and pectin, two kinds of natural polysaccharide were combined to fabricate chitosan-pectin composite microparticles by emulsion method. The characteristics and potential applications of the composite microprticles as drug delivery carriers were also investigated. First, the effects of various operating parameters for emulsion were studied. The results of size analysis showed that the microparticles prepared using surfactant Tween 81 had smaller size. To fix the microparticles, 1 hour of NaOH treatment time was sufficient without changing the size distributions of microparticles. As the total concentration of disperse phase (chitosan-pectin mixture solutions) increased, the yield of microparticles increased. The properties were further characterized of chitosan-pectin composite microparticles. The DSC results suggested that the interaction between chitosan and pectin did exist. The results of FTIR implied the presence of the interaction between amino groups of chitosan and carboxyl groups of pectin. Besides, according to the results of cell culture and MTT assay, the composite microparticles showed almost no cytotoxicity. The water-uptake capacity of composite microparticles increased as the ratio of chitosan to pectin increased. The erosion test showed that the erosion properties of composite mircroparticles were adjustable by altering the composition of microparticles. Finally, using BSA as a model drug, the encapsulation efficiency and release profile of BSA in the microparticles were measured. The results showed that enhanced encapsulation efficiency was achieved by using the composite microparticles. We also found that the more chitosn present in the microparticles, the faster the BSA released under acidic conditions. In contrast, the more pectin present in the microparticles, the faster the BSA released under basic conditions. In brief, the chitosan-pectin composite microparticles were prepared by emulsion method. The composite microparticles showed better encapsulation property, and adjustable BSA release profiles. The chitosan-pectin composite microparticles therefore have application potential in controlled release of drugs.

Chitosan microparticles ionically cross-linked with poly(γ-glutamic acid) as antimicrobial peptides and nitric oxide delivery systems

Preparation, characterization and stability evaluation of ionic liquid blended chitosan tripolyphosphate microparticles

Application of halloysite clay nanotubes as a pharmaceutical excipient

This study focuses on the development of a nanosupport based on halloysite nanotubes (HNTs), Fe3O4 nanoparticles (NPs), and thiolated chitosan (CTs) for laccase immobilization. First, HNTs were modified with Fe3O4 NPs (HNTs-Fe3O4) by the coprecipitation method. Then, the HNTs-Fe3O4 surface was tuned with the CTs (HNTs-Fe3O4-CTs) by a simple refluxing method. Finally, the HNTs- Fe3O4-CTs surface was thiolated (-SH) (denoted as; HNTs- Fe3O4-CTs-SH) by using the reactive NHS-ester reaction. The thiol-modified HNTs (HNTs- Fe3O4-CTs-SH) were characterized by FE-SEM, HR-TEM, XPS, XRD, FT-IR, and VSM analyses. The HNTs-Fe3O4-CTs-SH was applied for the laccase immobilization. It gave excellent immobilization of laccase with 100% activity recovery and 144 mg/g laccase loading capacity. The immobilized laccase on HNTs-Fe3O4-CTs-SH (HNTs-Fe3O4-CTs-S-S-Laccase) exhibited enhanced biocatalytic performance with improved thermal, storage, and pH stabilities. HNTs-Fe3O4-CTs-S-S-Laccase gave outstanding repeated cycle capability, at the end of the 15th cycle, it kept 61% of the laccase activity. Furthermore, HNTs-Fe3O4-CTs-S-S-Laccase was applied for redox-mediated removal of textile dye DR80 and pharmaceutical compound ampicillin. The obtained result marked the potential of the HNTs-Fe3O4-CTs-S-S-Laccase for the removal of hazardous pollutants. This nanosupport is based on clay mineral HNTs, made from low-cost biopolymer CTs, super-magnetic in nature, and can be applied in laccase-based decontamination of environmental pollutants. This study also gave excellent material HNTs-Fe3O4-CTs-SH for other enzyme immobilization processes.

Chitosan/halloysite nanotubes microcomposites: A double header approach for sustained release of ciprofloxacin and its hemostatic effects

pH-responsive polyacrylic acid (PAA)-carboxymethyl cellulose (CMC) hydrogel incorporating halloysite nanotubes (HNT) for controlled curcumin delivery

Improving the encapsulation efficiency and sustained release behaviour of chitosan/β-lactoglobulin double-coated microparticles by palmitic acid grafting.

The potential of chitosan-tripolyphosphate microparticles in the visualisation of latent fingermarks