A comparative study of chitosan and poloxamer based thermosensitive hydrogel for the delivery of PEGylated melphalan conjugates

Abstract

Objective: Although the melphalan (ML) used extensively for the management of breast cancer, its clinical application is limited due to significant hemolytic activity. In the present work, a comparative analysis of two distinct in situ-based thermogelling polymers of PEGylated ML was performed.

Methods: Briefly, the PEGylated conjugate of the melphalan (MLPEG 5000) for local and sustained drug release action is loaded into two different thermogelling polymeric systems, namely chitosan- and poloxamer-based systems. The synthesized conjugate was loaded to a chitosan (MLP 5000) and poloxamer-based (MPX-CG) thermogelling injectable hydrogels. These thermogelling hydrogels were evaluated for in vitro hydrolysis, in vitro hemolytic activity. and in vitro anticancer activity.

Results: The lower percent cumulative hydrolysis was witness for both the hydrogels. MPX-CG and MLP 5000 hydrogels as predicted had shown lower percent cumulative hydrolysis of 3.31?±?0.1 and 1.67?±?0.1 after 6?h. The percentage hemolysis of MPX-CG and MLP 5000 even at a concentration of 32?µg/ml was found to be 39.23?±?1.24% and 34.23?±?2.24%, observed at 1?h, respectively. Both the hydrogels showed similar anticancer pattern, the MPX-CG hydrogel showed low cell viability of 8.4?±?1.1% at a concentration of 150?µM and the MLP-5000 hydrogel showed slight higher cell viability (13.12?±?5.4%) as compared with MPX-CG hydrogel.

Conclusion: Hence, from the present study it can be well understood that both the chitosan- and the poloxamer-based thermogelling hydrogel proves to be an effective drug delivery systems for the delivery of the PEGylated conjugates.     

Injectable thermosensitive hydrogel based on chitosan and quaternized chitosan and the biomedical properties

A novel injectable thermosensitive hydrogel (CS–HTCC/α β-GP) was successfully designed and prepared using chitosan (CS), quaternized chitosan (HTCC) and α,β-glycerophosphate (α,β-GP) without any additional chemical stimulus. The gelation point of CS–HTCC/α β-GP can be set at a temperature close to normal body temperature or other temperature above 25°C. The transition process can be controlled by adjusting the weight ratio of CS to HTCC, or different final concentration of α,β-GP. The optimum formulation is (CS + HTCC) (2% w/v), CS/HTCC (5/1 w/w) and α,β-GP 8.33% or 9.09% (w/v), where the sol–gel transition time was 3 min at 37°C. The drug released over 3 h from the CS–HTCC/α,β-GP thermosensitive hydrogel in artificial saliva pH 6.8. In addition, CS–HTCC/α,β-GP thermosensitive hydrogel exhibited stronger antibacterial activity towards two periodontal pathogens (Porphyromonas gingivalis, P.g and Prevotella intermedia, P.i). CS–HTCC/α, β-GP thermosensitive hydrogel was a considerable candidate as a local drug delivery system for periodontal treatment.     

pH-responsive dual-functional hydrogel integrating localized delivery and anti-cancer activities for highly effective therapy in PDX of OSCC

As one of the most promising localized drug delivery systems for enhancing therapeutic efficacy and reducing systemic toxicity, supramolecular hydrogels self-assembled from natural products have recently attracted tremendous attention. However, the intricate drug loading process, limited drug entrapment efficacy, and lack of stimulus responsiveness considerably impede their potential for biological applications and raise the need for advanced hydrogel-based delivery systems. Therefore, the development of updated materials that integrate localized delivery and drug activity into a single system is extremely desired and has great potential to overcome the aforementioned shortcomings. In this study, a pH-responsive dual-functional isoG-based supramolecular hydrogel with both localized delivery and anti-cancer activity in one molecule is successfully developed in one pot by following a simple and green procedure. The isoguanosine-phenylboronic-guanosine (isoGPBG) hydrogel exhibits exceptional stability (more than one year), outstanding pH-responsiveness and excellent sustained release capability. Both in vitro and in vivo experiments demonstrate that the isoGPBG hydrogel not only shows acceptable biocompatibility and biodegradability but also significantly inhibit tumor growth (approximately 60% inhibition of tumor growth) and improve overall survival, especially in preclinical patient-derived xenograft (PDX) model of oral squamous cell carcinoma (OSCC). Therefore, the isoGPBG hydrogel, to the best of our knowledge, is the first example of pH-responsive dual-functional isoG-based supramolecular hydrogel integrating localized delivery and anti-cancer activity in one molecule. It is implied that the isoGPBG hydrogel could act as a smart dual-functional localized delivery system in the future for clinical cancer therapy.     

Synthesis and characterization of carboxymethyl chitosan hydrogel: Application as site specific delivery for lercanidipine hydrochloride

In the present study, carboxymethylchitosan (CMCS) was prepared from chitosan, crosslinked with glutaraldehyde and evaluated in vitro as a potential carrier for site specific drug delivery of lercanidipine hydrochloride (LERH). LERH was incorporated at the time of crosslinking of CMCS. The chitosan was evaluated for its degree of deacetylation (DD) and average molecular weight, which were found to be 84·6% and 3·5 × 10⁴ Da, respectively. The degree of substitution on prepared CMCS was found to be 0·68. All hydrogel formulations showed more than 86% and 77% yield and drug loading, respectively. The swelling behaviour of prepared hydrogels were checked in different pH values, 1·2, 6·8 and 7·4, indicated pH responsive swelling characteristic with very less swelling at pH 1·2 and quick swelling at pH 6·8 followed by linear swelling at pH 7·4 with slight increase. In vitro release profile was carried out at the same conditions as in swelling and drug release was found to be dependent on swelling of hydrogels and showed biphasic release pattern with non-fickian diffusion kinetics at higher pH. The carboxymethylation of chitosan, entrapment of drug and its interaction in prepared hydrogels were checked by FTIR, ¹H-NMR, DSC and p-XRD studies, which confirmed formation of CMCS from chitosan and absence of any significant chemical change in LERH after being entrapped in crosslinked hydrogel formulations. The surface morphology of formulation S6 was checked before and after dissolution, revealed open channel like pores formation after dissolution.     

"Nanohybrids" based on pH-responsive hydrogels and inorganic nanoparticles for drug delivery and sensor applications

Allyl-PEG capped inorganic NPs, including magnetic iron oxide (IONPs), fluorescent CdSe/ZnS quantum dots (QDs), and metallic gold (AuNPs of 5 and 10 nm) both individually and in combination, were covalently attached to pH-responsive poly(2-vinylpyridine-co-divinylbenzene) nanogels via a facile and robust one-step surfactant-free emulsion polymerization procedure. Control of the NPs associated to the nanogels was achieved by the late injection of the NPs to the polymerization solution at a stage when just polymeric radicals were present. Remarkably, by varying the total amount of NPs injected, the swelling behavior could be affected. Furthermore, the magnetic response as well as the optical features of the nanogels containing either IONPs or QDs could be modified. In addition, a radical quenching in case of gold nanoparticles was observed, thus affecting the final nanogel geometry.     

Entrapping multifunctional dendritic nanoparticles into a hydrogel for local therapeutic delivery and synergetic immunochemotherapy

Nano Research - Developing multifunctional nanoparticles to support new therapy models is a promising and challenging task to address the current dilemma on antitumor treatment. Herein, we...     

pH、离子强度敏感性壳聚糖水凝胶的合成及其对辅酶A的控制释放

以壳聚糖(CS),L-天冬氨酸(ASP)和戊二醛(GA)为原料,合成了具有pH、离子强度敏感性的壳聚糖水凝胶CS-GA-ASP.研究了交联剂含量、pH、离子强度对水凝胶溶胀率的影响和水凝胶对辅酶A的控制释放.结果表明,水凝胶在酸性溶液中,溶胀率最大,在中性溶液中溶胀率最小;水凝胶在不同pH或不同离子强度的溶液中交替放置时,表现出良好的溶胀-退胀可逆性;在室温下,pH=3.7、6.8、9的缓冲溶液中,辅酶A的累积释放率分别为78%、92%和87%,且在pH=6.8的缓冲溶液中,辅酶A释放速率最快,在pH=3.7的缓冲溶液中时,辅酶A释放速率最慢.     

Controlled drug delivery systems based on thiolated chitosan microspheres

The aim of the present study was to verify the potential of chitosan-thio-butyl-amidine (TBA) microspheres as carrier systems for controlled drug delivery. In this study microspheres were prepared utilizing water in oil (w/o) emulsification solvent evaporation technique. A concentration of 0.5% of chitosan-TBA conjugate displaying 100 µM thiol groups per gram polymer was used in the aqueous phase of the emulsion in order to prepare microspheres. The obtained non-aggregated free-flowing microspheres were examined with conventional light microscope as well as scanning electron microscopy (SEM). The microscopic images indicated that the prepared chitosan-TBA microspheres were of spherical shape and smooth surface while microparticles obtained from the unmodified chitosan were of porous structure and non-spherical shape. Particle size distribution was determined to be in the range from 1 to 59 µm. The free thiol group content of chitosan-TBA microspheres prepared with an aqueous phase of pH 2, 5, and 6.5 were determined to be 71.4, 49.4, and 8.2 µM/g polymer, respectively. Furthermore, results attained from in vitro release studies with fluorescein isothiocyanate labelled dextran (FITC-dextran) loaded chitosan-TBA microspheres showed a controlled release rate for more than three hours while the control reached the maximum peak level of release already within an hour. According to these results, chitosan-TBA microspheres seem to be a promising tool in transmucosal drug delivery for poorly absorbed therapeutic agents.     

多功能壳聚糖水凝胶医用材料的功能性研究

作为一类兼具应用价值和经济效益的新型功能高分子材料,水凝胶越来越受关注。以天然可降解的壳聚糖为载体,通过自由基接枝共聚法制备了壳聚糖水凝胶,重点研究了其吸附性及药物控释性能。结果表明:该水凝胶20d左右可以完全降解,降解性能良好。在25℃条件下,铜离子浓度为1200mg/L时,壳聚糖水凝胶对铜离子的平衡吸附量可达225.8mg/g。以亚甲基蓝为药物模型的控释实验结果表明,温度以及初始药物投加量对控释性能影响较大,48h累积释放率达70%左右,可在一定程度上实现缓释控释效果。     

Hydrogels based on chitosan and dextran as potential drug delivery systems

The release of human growth hormone (GH) from bioartificial polymeric materials in the form of hydrogels, was measured in vitro for up to 3 weeks. Poly(vinyl-alcohol) (PVA) was blended, in different ratios, with two biological polymers, dextran and chitosan respectively. These blends were used to prepare hydrogels, using a freeze–thawing method. The hydrogels were loaded with GH, and their potential use as delivery systems was investigated. The release with time of PVA, in aqueous medium, was also monitored and evaluated. Scanning electron microscopy was used to investigate the structure of the hydrogels. The results obtained indicated that GH can be released from both dextran/PVA and chitosan/PVA hydrogels. The initial GH concentration used for sample loading affected the total quantity of GH released but not the pattern of release. The amount of GH released was affected by the content of the biological component. The percentage of PVA released was low but it was, however, related to the content of chitosan and dextran in the blends. ©1999 Kluwer Academic Publishers     

Characterization and cytocompatibility of thermosensitive hydrogel embedded with chitosan nanoparticles for delivery of bone morphogenetic protein-2 plasmid DNA

A novel injectable chitosan thermosensitive hydrogel was designed as a target multi-effect scaffold for endogenous repair of the periodontium. The hydrogel complex was designed by embedding chitosan nanoparticles (CSn) loaded with bone morphogenetic protein-2 plasmid DNA (pDNA-BMP2) into a chitosan (CS)-based hydrogel with α,β-glycerophosphate (α,β-GP), termed CS/CSn(pDNA-BMP2)-GP. Characterization, the in vitro release profile for pDNA-BMP2, and cytocompatibility to human periodontal ligament cells (HPDLCs), were then conducted. The average diameter of the CSn(pDNA-BMP2) was 270.1 nm with a polydispersity index (PDI) of 0.486 and zeta potential of +27.0 mv. A DNase I protection assay showed that CSn could protect the pDNA-BMP2 from nuclease degradation. Encapsulation efficiency and loading capacity of CSn(pDNA-BMP2) were more than 80 and 30 %, respectively. The sol–gel transition time was only 3 min when CSn(pDNA-BMP2) was added into the CS/α,β-GP system. Scanning electron microscopy showed that CSn(pDNA-BMP2) was randomly dispersed in a network with regular holes and a porous structure. Weighting method showed the swelling ratio and degradation was faster in medium of pH 4.0 than pH 6.8. An in vitro pDNA-BMP2 release test showed that the cumulative release rate of pDNA-BMP2 was much slower from CS/CSn-GP than from CSn in identical release media. In release media with different pH, pDNA-BMP2 release was much slower at pH 6.8 than at pH 4.0. Three-dimensional culture with HPDLCs showed good cell proliferation and the Cell-Counting Kit-8 assay indicated improved cell growth with the addition of CSn(pDNA-BMP2) to CS/α,β-GP. In summary, the CS/CSn(pDNA-BMP2)-GP complex system exhibited excellent biological properties and cytocompatibility, indicating great potential as a gene delivery carrier and tissue regeneration scaffold for endogenous repair of the periodontium.     

双氯灭痛壳聚糖水凝胶微球的制备及其性能研究

在Span80与植物油形成的反相胶束体系中,通过戊二醛交联制备出壳聚糖水凝胶微球(CHM)。采用红外光谱和透射电镜等方法对CHM结构及粒子形态进行了研究。同时对CHM的溶胀度及其对模型药物双氯灭痛的体外释放行为进行了考察。结果表明,CHM具有较好的控制药物释放的作用。交联程度对微球粒径、溶胀度及药物释放性能影响较大。     

Preparation and properties of an injectable thermo-sensitive double crosslinking hydrogel based on thiolated chitosan/beta-glycerophosphate

An injectable thermo-sensitive double crosslinking hydrogel based on thiolated chitosan (CS-TGA)/beta-glycerophosphate (β-GP) was prepared by combining physical and chemical crosslinking. The effect of the concentrations of CS-TGA and β-GP on gelation temperature of CS-TGA-GP hydrogel was investigated. The gelation and mechanical properties of CS-TGA-GP in situ gel system were studied by oscillatory rheology and unconfined compression testing. By the physical interaction of CS-TGA and β-GP, CS-TGA-GP system undergoes a fast gelation at body temperature within 2 min. In addition, CS-TGA-GP hydrogel contains a low concentration of β-GP, which significantly decreases the toxicity of the gel. Owing to the chemical crosslinking of disulfide bonds, the gel is durable and possesses high-mechanical strength without introducing any potential cytotoxicity. The integrity of CS-TGA-GP hydrogel maintains for more than 30 days both in vitro and in vivo, and the interior morphology visualized by scanning electron microscopy reveals that the gel has interconnected porous network structure. In vitro release behavior of protein from CS-TGA-GP hydrogel was investigated using BSA as model protein. There is a sustained protein release from the gel without any initial burst. In vitro cytotoxicity, hemolysis, and histopathological analysis reveal that the gel is biocompatible. These features indicate that CS-TGA-GP hydrogel is a promising candidate for injectable protein delivery system and biomedical applications.     

Effect of hydroxyapatite nanoparticles on ibuprofen release from carboxymethyl-hexanoyl chitosan/O-hexanoyl chitosan hydrogel

In order to explore the effect of nanofiller on the regulation of the drug release behavior from microsphere-embedded hydrogel prepared by carboxymethyl-hexanoyl chitosan (HNOCC) and O-hexanoyl chitosan (OHC), the release kinetics was investigated in terms of various amounts of calcium-deficient hydroxyapatite (CDHA) nanoparticles incorporated. HNOCC is a novel chitosan-based hydrophilic matrix with a burst release profile in a highly swollen state. The drug release kinetics of the HNOCC hydrogel can be regulated by incorporation of well-dispersed CDHA nanoparticles. It was found that the release duration of ibuprofen (IBU) from HNOCC was prolonged with increasing amounts of CDHA which acts as a crosslink agent and diffusion barrier. On the contrary, the release duration of the IBU from OHC (hydrophobic phase) was shortened through increasing the CDHA amount over 5%, which is due to the hydrophilic nature of the CDHA nanoparticles destroying the intermolecular hydrophobic interaction and accelerating OHC degradation. Thus, water accessibility and molecular relaxation were enhanced, resulting in a higher release rate. In addition, sustained and sequential release behavior was achieved by embedding the OHC microspheres (hydrophobic phase) into the HNOCC (hydrophilic phase) matrix, which could significantly prolong the release duration of the HNOCC drug-loaded implant.     

壳聚糖/聚醚半互穿网络水凝胶的合成与力学性能的研究

介绍了交联壳聚糖／聚醚半互穿网络水凝胶的制备方法,研究了温度、聚醚与壳聚糖质量比、交联剂戊二醛浓度等对壳聚糖／聚醚半互穿网络水凝胶的溶胀度、硬度的影响,采用正交实验对工艺条件进行了优化,实验结果表明当凝胶温度为45℃,聚醚与壳聚糖质量比为0．6,交联剂浓度为1．599mol／L,其凝胶硬度最大。     

Thermosensitive hydrogel of hydrophobically-modified methylcellulose for intravaginal drug delivery

Hydrogels with the advantages of prolonging drug release and administration convenience are necessary for intravaginal drug delivery to prevent sexual transmission of human immunodeficiency virus and other vaginal infections. In this study, the thermosensitive hydrogel of methylcellulose modified by stearic acid (MCS) were evaluated in the presence of NaCl and phosphates, which exhibited sol-to-gel transition performance at body temperature or even lower. The in vitro cytotoxicity and in vivo mucosal irritation were investigated and the results showed that MCS hydrogel possessed good biocompatibility similar with hydroxyethyl cellulose (HEC) gel. Significantly, the release studies revealed that MCS hydrogel could control tenofovir sustained release for 10 h without burst release, longer than that from HEC gel or poloxamer 407 hydrogel. Therefore, MCS thermosensitive hydrogel would be a promising carrier for intravaginal delivery of antiviral drugs for long time controlled release.     

Preparation and characterization of chitosan hydrogel membrane for the permeation of 5-Fluorouracil

Four kinds of chitosan membranes, (Ch, C-G, C-N, and C-GN), were prepared in this study. Ch system of chitosan membranes were prepared by solution casting method without any treatment. C-G system of chitosan membranes were prepared by solution casting method with adding glutaraldehyde as crosslinking agent. C-N system of chitosan membranes were prepared by solution casting method with the treatment of NaOH solution. C-GN system of chitosan membranes were crosslinked with glutaraldehyde and treated with 1 M NaOH solution. Infrared spectroscopy and differential scanning calorimetry (DSC) were conducted to characterize the structure and thermal properties of chitosan membrane. To evaluate the usage of chitosan for the carrier of drug, water content and degradation of the chitosan membrane were determined. It was found that the values of equilibrated water content in chitosan membranes increased with the chitosan content in the stock chitosan solution. The assessment of 5-FU permeability through the chitosan membranes was determined. The linear relationship between the permeability of 5-FU through the membrane and the wt.% of chitosan content in stock chitosan solution was found. Both values of intercept and slope were determined. The value of intercept means that the permeability of 5-FU through the chitosan membrane, which is assumed to be prepared from stock chitosan solution containing infinite dilute chitosan content. The value of slope indicates that the effect of the treatment method on the permeability of 5-FU through the chitosan membrane. From the evaluation of normalized flux, diffusivity and saturation concentration of 5-FU in various chitosan membrane, it was found that more number of 5-FU molecules were trapped in the chitosan membrane of C-GN system than that in C-N system and resulted in the decrease of diffusivity of 5-FU molecules through the chitosan membrane.     

Alginate microsphere-collagen composite hydrogel for ocular drug delivery and implantation

A composite collagen hydrogel containing protein encapsulated alginate microspheres was developed for ocular applications. Bovine serum albumin (BSA) served as a drug model. The composite hydrogel retained optical clarity and mechanical robustness of control hydrogels without microspheres. A sustained release of BSA was achieved during an 11-day period in neutral phosphate buffer. The composite hydrogel supported human corneal epithelial cell growth and had adequate mechanical strength and excellent optical clarity for possible use as therapeutic lens for drug delivery and/or use as corneal substitute for transplantation into patients who have corneal diseases.