Hydrophilicity/Hydrophobicity reversable and redox-sensitive nanogels for anticancer drug delivery.

Long circulation in the blood, efficient cellular internalization, and intracellular drug release in the tumor cells are major challenges in the development of ideal anticancer drug delivery systems. In this paper, hydrophilicity/hydrophobicity reversable and redox-sensitive poly(oligo(ethylene glycol) methacrylates-ss-acrylic acid) (P(OEGMAs-ss-AA)) nanogels were constructed as drug carriers for cancer therapy. The nanogels underwent a pH-dependent hydrophilic/hydrophobic change. The nanogels were hydrophilic under physiological conditions (pH 7.4, 37 °C), resulting in fewer opsonization of proteins and less phagocytosis by macrophage RAW264.7 cells, while they were hydrophobic in the tumor tissues (pH 6.5, 37 °C), resulting in strong internalization by Bel7402 cells. The doxorubicin (DOX) release from DOX-loaded nanogels was increased in intracellular reductive and lysosome acidic environments. DOX-loaded nanogels exhibited higher cellular proliferation inhibition to GSH-OEt-pretreated Bel7402 cells at pH 6.5 than to unpretreated cells at pH 7.4. Further studies showed that the loaded DOX and nanogels were internalized into the cells together via both lipid raft/caveolae- and clathrin-mediated endocytic pathways. After internalization, the DOX-loaded nanogels were transported via the specific route in endo/lysosomal system. The loaded DOX was released from the nanogels with the introduction of intracellular GSH and entered the nucleus. This study indicated that the hydrophilicity/hydrophobicity reversable and redox-sensitive nanogels might be used as potential carriers for anticancer drugs, which provided a foundation for designing an effective drug delivery system for cancer therapy.

A facile construction strategy of stable lipid nanoparticles for drug delivery using a hydrogel-thickened microemulsion system.

We report a novel facile method for preparing stable nanoparticles with inner spherical solid spheres and an outer hydrogel matrix using a hot O/W hydrogel-thickened microemulsion with spontaneous stability. The nanoparticles with average diameters of about 30.0 nm and 100.0 nm were constructed by cooling the hot hydrogel-thickened microemulsion at different temperatures, respectively. We explained the application of these nanoparticles by actualizing the cutaneous delivery of drug-loaded nanoparticles. The in vitro skin permeation studies showed that the nanoparticles could significantly reduce the penetration of model drugs through skin and resulted in their dermal uptakes in skin. The sol-gel process of TEOS was furthermore used in the template of HTM to regulate the particle size of nanoparticles. The coating of silica on the surface of nanoparticles could regulate the penetration of drug into skin from dermal delivery to transdermal delivery. This strategy provides a facile method to produce nanoparticles with long-term stability and ease of manufacture, which might have a promising application in drug delivery.

Influence of polyethyleneglycol modification on phagocytic uptake of polymeric nanoparticles mediated by immunoglobulin G and complement activation.

The purpose of this study is to investigate the influence of polyethyleneglycol (PEG) modification on in vitro phagocytic uptake of polymeric nanoparticles (NPs) mediated by immunoglobulin G (IgG) and complement activation. A series of PEG-modified poly (D, L-lactide-co-glycolide) nanoparticles (PEG-PLGA-NPs) were incubated in pure serum protein or whole serum, and their capacity for adsorbing albumin and the serum total proteins was measured by a bicinchoninic acid (BCA) protein assay. The adsorption of serum total IgG and complement activation was investigated by enzyme-linked immunosorbent assay (ELISA). To measure in vitro uptake, various fluorescently labeled (Nile red) PEG-PLGA-NPs were opsonized by different pre-treated sera and subsequently incubated with phagocytes. The uptake of NPs by macrophages was then measured by fluorescence spectrometry. Longer chain length and appropriate content PEG reduced the adsorption of serum proteins and complement activation by NPs via both the classical and the alternative pathways. The phagocytosis of PEG-PLGA-NPs by murine peritoneal macrophages (MPMs) involved both serum-independent and serum-dependent phagocytosis. PEG modification was shown only to reduce serum-dependent phagocytosis, mainly by inhibiting IgG adsorption and complement activation on NP surfaces, and the effect of complement activation was greater than that of IgG. The results of this study provided new information that may assist in the design of more efficient nano drug carriers for medical applications.

A novel method for the separation and determination of non-encapsulated pyrene in plasma and its application in pharmacokinetic studies of pyrene-loaded MPEG-PLA based nanoparticles.

During the pharmacokinetic processes of nanoparticles, encapsulated drugs and non-encapsulated (free and protein-bound) drugs are the drug forms existing in plasma. It is necessary and important to measure the bioavailable drug concentration, namely, the non-encapsulated drug concentration, in pharmacokinetic studies of nanoparticles. A new method using liquid-liquid extraction was first developed and validated for the separate determination of non-encapsulated drugs in plasma. The method was based on the significant difference of extractability between non-encapsulated and encapsulated drugs, and used n-heptane as an extractant. Satisfactory results were obtained with a good linear relationship in the range of 1-80 ng ml(-1) (r = 0.9999) and good reproducibility with coefficients of variation (CVs) less than 10% of intra- and inter-day evaluation results, and the accuracy of intra- and inter-day evaluation results ranged from 92.4% to 109.2%. The extraction recovery was stable in the range 68.6%-75.6%. The developed method had been proven to be an ideal method with high specificity and sensitivity, and the method is simple and rapid. The method described herein has been successfully applied for pharmacokinetic studies in female Wistar rats after the administration of a 5 mg equivalent pyrene kg(-1) dose of pyrene-loaded nanoparticles. The results showed that the non-encapsulated drug had a different pharmacokinetic behavior compared with that of the total drug.

The decrease of PAMAM dendrimer-induced cytotoxicity by PEGylation via attenuation of oxidative stress.

Due to their unique structure, poly(amidoamine) (PAMAM) dendrimers have been widely used in medical applications. However, PAMAM dendrimers bearing amino terminals show certain cytotoxicity. In order to improve their biocompatibility, we modified Generation-5 PAMAM dendrimers by conjugating them with poly(ethylene glycol) (PEG) of two different molecular weights and different number of chains. The IC(50) values of PEGylated dendrimers were 12-105 fold higher than those of PAMAM dendrimers. To investigate the influence of PEGylation on PAMAM-induced cytotoxicity, the intracellular responses, reactive oxygen species (ROS) content, mitochondrial membrane potential (MMP), and apoptosis were examined. The results indicated that conjugation with PEG could effectively reduce the PAMAM-induced cell apoptosis by attenuating the ROS production and inhibiting PAMAM-induced MMP collapse. Meanwhile, dendrimers conjugated with less PEG of lower molecular weight did not significantly change the endocytic properties. Dendrimers conjugated with more PEG of higher molecular weight were much less cytotoxic. This study provided a novel insight into the effects of PEGylation on the decrease of cytotoxicity at the molecular level.

Preparation and characterization of PEG-modified polyurethane pressure-sensitive adhesives for transdermal drug delivery.

BACKGROUND: The purpose of this work was to develop novel pressure-sensitive adhesives (PSAs) for transdermal drug-delivery systems (TDDS) with proper adhesive properties, hydrophilicity, biocompatibility and high drug loading. METHOD: Polyethyleneglycol-modified polyurethane PSAs (PEG-PU-PSAs) were synthesized by prepolymerization method with PEG-modified co-polyether and hexamethylene diisocyanate. The effects of reaction temperature, catalyst, ratios of NCO/OH, co-polyether composition, and chain extender were investigated. Drug loading was studied by using thiamazole (hydrophilic drug), diclofenac sodium (slightly hydrophilic drug), and ibuprofen (lipophilic drug) as model drugs. In vitro drug-release kinetics obtained with Franz diffusion cell and dialysis membrane. RESULTS: The results showed that when reaction temperature at 80 degrees C, weight percentage of stannous octoate as catalyst at 0.05%, ratio of NCO/OH at 2.0-2.2, ratio of PEG/polypropylene glycol (PPG)/polytetramethylene ether glycol (PTMG) at 30/25-30/50-55, and weight percentage of glycol as chain extender at 4.5%, PEGPU-PSAs synthesized performed well on adhesive properties. Actually, PEG on the main chain of the PU could improve the hydrophilicity of PSAs, whereas PPG and PTMG could offer proper adhesive properties. Skin compatibility test on volunteers indicated that PEG-PU-PSAs would not cause any skin irritations. All the model drugs had excellent stabilizations in PEG-PU-PSAs. In vitro drug-release kinetics demonstrated that the drug release depended on drug-loading level and solubility of the drug. CONCLUSION: These experimental results indicated that PEG-PU-PSAs have good potential for applications in TDDS.

Emulsifiers' composition modulates venous irritation of the nanoemulsions as a lipophilic and venous irritant drug delivery system.

In this study, a nanoemulsion (NE) system was investigated for intravenous delivery of lipophilic and venous irritant drugs. NEs were prepared to deliver diallyl trisulfide (DT) for systemic therapy of bacterial and fungal infection, egg phospholipid was chosen as the main emulsifier, and two co-emulsifiers were also incorporated, including Poloxamer 188 (P188) and Solutol HS 15 (S15). Soybean oil was used as the dispersed phases, forming stable DT NEs with small particle sizes. The venous irritation of DT NEs was evaluated by in vitro human umbilical cord endothelial cells (CRL 1730) compatibility model with the intracellular adenosine triphosphate (ATP) and guanosine triphosphate (GTP) concentrations as the indices. The intracellular ATP and GTP reduction changed with the incorporation of a variety of co-emulsifiers, which varied in a free DT concentration-dependent manner. It was deduced that the free DT concentrations of NEs containing co-emulsifiers were determined by the partition coefficient of DT between oil and surfactant buffer solution. In conclusion, NE was an appropriate delivery system for lipophilic and venous irritant drug, and optimization of the composition of emulsifiers was an effective method to alleviate the venous irritation of DT NEs.

Anti-tumour and immuno-modulation effects of triptolide-loaded polymeric micelles.

Triptolide (TP) possesses both anti-tumour and immuno-suppressive activities. Its immuno-suppressive activity may be disadvantageous for the therapy of cancers. A novel polymeric micelle system containing TP (TP-PM) was constructed by the solvent evaporation method using methoxypolyethylene glycol-poly(d,l-lactic acid)-block copolymer as the carrier, and was characterised using photon correlation spectroscopy, transmission electron microscopy and high performance liquid chromatography. The anti-tumour and immuno-modulation effects of TP-PM were evaluated in sarcoma 180-bearing mice and A2780 cells. Results demonstrated that TP-PM had an average diameter of 78.9 nm, encapsulation efficiency of 66.7%, core-shell morphology and a long-term stability. TP-PM could significantly inhibit tumour growth via intravenous injections at the dose levels of 0.0375, 0.075 and 0.15 mg/kg, and their inhibition rates were 42.5%, 46.0% and 49.9%, respectively; they showed similar cytotoxicity against A2780 cells compared to that of TP. Simultaneously, TP-PM had no effect on the thymus index, spleen index, spleen lymphocyte proliferation and the TNF-alpha and IL-2 levels in serum as compared with TP. Therefore, TP encapsulated in polymeric micelles does not demonstrate immuno-suppressive activity but does not lose its anti-tumour effect. These results show that polymeric micelles are a promising carrier for cancer therapy using TP.

Controlled poorly soluble drug release from solid self-microemulsifying formulations with high viscosity hydroxypropylmethylcellulose.

The objective of this work was the development of a controlled release system based on self-microemulsifying mixture aimed for oral delivery of poorly water-soluble drugs. HPMC-based particle formulations were prepared by spray drying containing a model drug (nimodipine) of low water solubility and hydroxypropylmethylcellulose (HPMC) of high viscosity. One type of formulations contained nimodipine mixed with HPMC and the other type of formulations contained HPMC and nimodipine dissolved in a self-microemulsifying system (SMES) consisting of ethyl oleate, Cremophor RH 40 and Labrasol. Based on investigation by transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray powder diffraction, differences were found in the particle structure between both types of formulations. In vitro release was performed and characterized by the power law. Nimodipine release from both types of formulations showed a controlled release profile and the two power law parameters, n and K, correlated to the viscosity of HPMC. The parameters were also influenced by the presence of SMES. For the controlled release solid SMES, oil droplets containing dissolved nimodipine diffused out of HPMC matrices following exposure to aqueous media. Thus, it is possible to control the in vitro release of poorly soluble drugs from solid oral dosage forms containing SMES.

Effect of poly(D, L-lactic acid) nanoparticles as triptolide carrier on abating rats renal toxicity by NMR-based metabolic analysis.

The aim of this study is to investigate the effect of poly(D, L-lactic acid) (PLA) nanoparticles as triptolide carrier on abating renal toxicity for Sprague Dawley rats after oral administration. Triptolide has severe toxicities on digestive, urogenital and blood circulatory system. High-resolution 600-MHz 1H-nuclear magnetic resonance (1H-NMR)-based metabolic analysis was performed on urine samples obtained from five groups of Sprague Dawley rats administrated with free triptolide and triptolide-loaded PLA nanoparticles at day 5, 10 and 15. The relative concentrations of biomarkers for renal lesion caused by triptolide were determined by 1H-NMR. The disorder of metabolism was characterized by the exceptional changes of the relative concentrations of succinate, 2-oxoglutarate and citrate. Similarly, the renal lesion was characterized by an increase of the relative concentrations of trimethylamine N-oxide and dimethylglycine, and a decrease of that of urea and allantoin. These results revealed that triptolide-loaded PLA nanoparticles might abate the renal toxicity of triptolide in comparison with identical doses of the free drug. The higher the dose (0.6 mg/kg), the more pronounced was this trend during long-term application. These results were further confirmed by histopathological changes. These results indicated that PLA nanoparticles provided a promising new formulation to abate the renal toxicity caused by triptolide.

Drug release behavior from in situ gelatinized thermosensitive nanogel aqueous dispersions.

In situ gellable thermosensitive poly(N-isopropylacrylamide-co-acrylamide) (designated as PNIP/AAm) nanogel aqueous dispersions were prepared through precipitation polymerization. Their thermosensitive volume phase transition and in situ gel-forming behavior were investigated. 5-Fluorouracil (5-Fu) and bovine serum albumin (BSA) were used as model drugs. The drug-loading properties of PNIP/AAm nanogel particles and release behavior from in situ gelatinized PNIP/AAm nanogel aqueous dispersions were investigated. The prepared PNIP/AAm nanogel particles and aqueous dispersions show good thermosensitivity. The presence of the drugs in the systems has no significant influence upon the thermosensitivity of the systems. In addition, the amount of cross-linker used in the preparation of the PNIP/AAm nanogel has little influence upon the drug-loading capability of PNIP/AAm nanogel particles and also on the release behavior from gelatinized dispersions. It was found that the drug-loading efficacy and entrapment efficiency of PNIP/AAm nanogel particles for low molecular weight 5-Fu was higher than that for biomacromolecular BSA. Furthermore, the cumulative release ratios of 5-Fu from in situ gelatinized PNIP/AAm nanogel aqueous dispersions were distinctly higher than that of BSA. These results imply potential application of prepared thermosensitive nanogel dispersions as embolizing and tissue engineering materials.

Investigation of the carbopol gel of solid lipid nanoparticles for the transdermal iontophoretic delivery of triamcinolone acetonide acetate.

The purpose of this study was to investigate solid lipid nanoparticles (SLN) hydrogel for transdermal iontophoretic drug delivery. Triamcinolone acetonide acetate (TAA), a glucocorticoids compound, was employed as the model drug. SLN containing the drug triamcinolone acetonide acetate (TAA-SLN) and their carbopol gel with stable physicochemical properties were prepared. The use of TAA-SLN carbopol gel as a vehicle for the transdermal iontophoretic delivery of TAA was evaluated in vitro using horizontal diffusion cells fitted with porcine ear skin. We found that the TAA-SLN gel possessed good stability, rheological properties, and high electric conductance. Transdermal penetration of TAA from TAA-SLN gel cross the skin tissue was significantly enhanced by iontophoresis. The enhancement of the cumulative penetration amount and the steady-state penetration flux of the penetrated drug were related to the particle size of TAA-SLN and the characteristics of the applied pulse electric current, such as density, frequency, and on/off interval ratio. These results indicated that SLN carbopol gel could be used as a vehicle for transdermal iontophoretic drug delivery under suitable electric conditions.

Hydrogel-thickened nanoemulsion system for topical delivery of lipophilic drugs.

In this work, a hydrogel-thickened nanoemulsion system (HTN) with powerful permeation ability, good stability and suitable viscosity was investigated for topical delivery of active molecules. HTN was prepared to deliver an oily mixture of 5% camphor, 5% menthol and 5% methyl salicylate for topical therapy of arthritis, minor joint and muscle pain using soybean oil as the oil phase, soybean lecithin, Tween 80 and poloxamer 407 as the surfactants, propylene glycol as the cosurfactant, carbomer 940 as a thickening agent. The HTN system was found to combine the o/w microstructure of nanoemulsion with the gel network of hydrogel and had a suitable viscosity of 133.2PaS. The system had small average diameters and good long-term stability. The abilities of HTN to deliver the high amounts of camphor, menthol and methyl salicylate were evaluated using the in vitro permeation studies. The permeation rates of camphor, menthol and methyl salicylate from the optimal HTN formulation were 138.0+/-6.5, 63.6+/-3.3, 53.8+/-3.2 microg cm(-2) h(-1) and showed the significant advantages over the control gel. The HTN with good stability and powerful permeation enhancing ability and suitable viscosity might be a promising prospective carrier for topical delivery of lipophilic drugs.

Tablets with material gradients fabricated by three-dimensional printing.

Complex tablets with zero-order drug release characteristics were fabricated using three-dimensional printing processes. The matrix tablets exhibited material gradients in radial direction and had drug-free release-barrier layers on both bases. The content of model drug acetaminophen incorporated in the tablets through premixing reached up to 68% of the tablets' weight. Tablets with ethylcellulose gradients showed acceptable mechanical and pharmacotechnical properties, as indicated by crushing strength, friability, and content uniformity tests. The structure and the gradients of ethylcellulose in the tablets were envisaged through environmental scanning electron microscopy and fluorescence tracing technique. Erosion and dissolution studies in vitro indicated that drug was released via a two-dimensional surface erosion mechanism, and 98% of the drug could be released linearly in 12 h. Tablets with other release-retardation material gradients such as sodium lauryl sulfate, stearic acid, and Eudragit RS-100 showed similar release-retardation effects by different release-retardation mechanisms. Through the printing of release-retardation materials, 3DP processes could easily prepare tablets with high dosage and special design features for furnishing the desired drug release characteristics.

Tumor necrosis factor alpha blocking peptide loaded PEG-PLGA nanoparticles: preparation and in vitro evaluation.

Nanoparticles prepared from polyethyleneglycol-modified poly(d,l-lactide-co-glycolide) (PEG-PLGA-NPs) are being extensively investigated as drug carriers due to their controlled release, biodegradable and biocompatibility. The purpose of this study was to evaluate the in vitro characteristics of PEG-PLGA-NPs loading tumor necrosis factor alpha blocking peptide (TNF-BP). PEG-PLGA copolymer was synthesized by ring-opening polymerization of d,l-lactide, glycolide and methoxypolyethyleneglycol (mPEG) (Mw = 5000). Blank PEG-PLGA-NPs, with particle size within the range of 79.7 to 126.1 nm and zeta potential within the range of -12.91 to -24.55 mV, were prepared by the modified-spontaneous emulsification solvent diffusion (modified-SESD) method. PEG-PLGA-NPs uptake by murine peritoneal macrophages (MPM) was lower than that of PLGA-NPs. TNF-BP was loaded on the blank nanoparticles by electrostatic interactions, and TNF-BP loading capacity of PEG-PLGA-NPs was found to be dependent on the characteristics of blank nanoparticles, peptide concentration and incubation medium. In vitro release experiments showed the peptide release rate affected by the drug loading and ionic strength, and approximately 60.2% of TNF-BP released from nanoparticles still possessed bioactivity. These experimental results indicate that PEG-PLGA-NPs could be used to develop as drug carriers for TNF-BP.

Hydrogel-thickened microemulsion for topical administration of drug molecule at an extremely low concentration.

In this work, a hydrogel-thickened microemulsion (HTM) was investigated for delivering an extremely low concentration of drug molecule. The pseudo-ternary phase diagrams were constructed using isopropyl myristate (IPM), Tween 80, propylene glycol and water. The various HTM were prepared and characterized. We described that HTM has the combination of o/w microstructure of microemulsion and the three-dimensional gel network of hydrogel in continuous phase using transmission electron microscope. The stability tests showed that HTM had good stability. The influence of the addition of hydrogel into microemulsions on the viscosity and permeation ability is investigated. The abilities of HTM to deliver an extremely low concentration of triptolide as a model drug were evaluated using the in vitro permeation studies. The permeation rates of triptolide from various HTM were 2.2-3.6 times over that from the control hydrogel. The addition of 2% menthol into HTM consisting of 3% IPM, 30% Tween 80, 15% propylene glycol, 0.75% carbomer 940 resulted in the highest permeation rate of 0.105+/-0.006microcm(-2)h(-1), which was 5.8 times over control gel. The powerful permeation enhancing ability of HTM with a suitable viscosity makes it promising alternative carrier for transdermal administration of drug molecule at an extremely low concentration.

An attempt to directly trace polymeric nanoparticles in vivo with electron microscopy.

This work attempted to directly observe polymeric nanoparticles in vivo by analytical electron microscopy (AEM) using copper chlorophyll as the contrast agent, based on the experiments concerned with the copper chlorophyll labeled poly-DL-lactide nanoparticles and the in vivo distribution of the polysorbate 80 (T-80)-coated nanoparticles in brain tissues. With the nanoprecipitation method without surfactants, copper chlorophyll is aggregated in the coordinately saturated form and encapsulated by the matrices of nanoparticles, which may ensure the stability of copper chlorophyll during the in vivo experiments. From both morphological information and chemical information, only the labeled nanoparticles with the T-80 coating were directly traced in the brain by AEM. The results not only support the mechanism of endocytosis and/or transcytosis of T-80-coated nanoparticles targeted to the brain but also verify that it is practical to probe polymeric nanoparticles in vivo using AEM together with copper chlorophyll as the contrast agent.

Microemulsion-based hydrogel formulation of ibuprofen for topical delivery.

The purpose of this study was to construct microemulsion-base hydrogel formulation for topical delivery of ibuprofen. Ethyl oleate (EO) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems and excellent skin permeation rate of ibuprofen. The pseudo-ternary phase diagrams for microemulsion regions were constructed using ethyl oleate as the oil, Tween 80 as the surfactant, propylene glycol as the cosurfactant. Various microemulsion formulations were prepared and the abilities of various microemulsions to deliver ibuprofen through the skin were evaluated in vitro using Franz diffusion cells fitted with porcine skins. The in vitro permeation data showed that microemulsions increased the permeation rate of ibuprofen 5.72-30.0 times over the saturated solution. The optimum formulation consisted of 3% ibuprofen, 6% EO, 30% Tween 80/PG (2:1) and water, showed a high permeation rate of 38.06 microg cm(-2) h(-1). Xanthan gum as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The studied microemulsion-based hydrogel showed a good stability. These results indicate that the studied microemulsion-based hydrogel may be a promising vehicle for topical delivery of ibuprofen.

Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration.

Doxorubicin (DOX)-induced co-assembling nanomedicines (D-PNAx) with temperature-sensitive PNAx triblock polymers have been developed for regional chemotherapy against liver cancer via intratumoral administration in the present work. Owing to the formation of insoluble DOX carboxylate, D-PNAx nanomedicines showed high drug-loading and entrapment efficacy via a simple mixing of doxorubicin hydrochloride and PNAx polymers. The sustained releasing profile of D-PNA100 nanomedicines indicated that only 9.4% of DOX was released within 1day, and 60% was released during 10days. Based on DOX-induced co-assembling behavior and their temperature sensitive in-situ-forming hydrogels, D-PNA100 nanomedicines showed excellent antitumor activity against H22 tumor using intratumoral administration. In contrast to that by free DOX solution (1.13±0.04 times at 9days) and blank PNA100 (2.11±0.34 times), the tumor volume treated by D-PNA100 had been falling to only 0.77±0.13 times of original tumor volume throughout the experimental period. In vivo biodistribution of DOX indicated that D-PNA100 nanomedicines exhibited much stronger DOX retention in tumor tissues than free DOX solution via intratumoral injection. D-PNA100 nanomedicines were hopeful to be developed as new temperature sensitive in-situ-forming hydrogels via i.t. injection for regional chemotherapy.