pH-sensitive Polymer Research Articles

Brain Co-Delivery of Temozolomide and Cisplatin for Combinatorial Glioblastoma Chemotherapy.

Glioblastoma (GBM) is an intractable malignancy with high recurrence and mortality. Combinatorial therapy based on temozolomide (TMZ) and cisplatin (CDDP) shows promising potential for GBM therapy in clinical trials. However, significant challenges include limited blood-brain-barrier (BBB) penetration, poor targeting of GBM tissue/cells, and systemic side effects, which hinder its efficacy in GBM therapy. To surmount these challenges,new GBM-cell membrane camouflaged and pH-sensitive biomimetic nanoparticles (MNPs) inspired by the fact that cancer cells readily pass the BBB and localize with homologous cells, are developed. This study's results show that MNPs can efficiently co-load TMZ and CDDP, transport these across the BBB to specifically target GBM. Incorporation of pH-sensitive polymer then allows for controlled release of drug cargos at GBM sites for combination drug therapy. Mice bearing orthotopic U87MG or drug-resistant U251R GBM tumor and treated with MNPs@TMZ+CDDP show a potent anti-GBM effect, greatly extending the survival time relative to mice receiving single-drug loaded nanoparticles. No obvious side effects are apparent in histological analyses or blood routine studies. Considering these results, the study's new nanoparticle formulation overcomes multiple challenges currently limiting the efficacy of combined TMZ and CDDP GBM drug therapy and appears to be a promising strategy for future GBM combinatorial chemotherapy.

PH-sensitive packaging of cationic particles by an anionic block copolymer shell

Cationic non-viral vectors show great potential to introduce genetic material into cells, due to their ability to transport large amounts of genetic material and their high synthetic versatility. However, designing materials that are effective without showing toxic effects or undergoing non-specific interactions when applied systemically remains a challenge. The introduction of shielding polymers such as polyethylene glycol (PEG) can enhance biocompatibility and circulation time, however, often impairs transfection efficiency. Herein, a multicomponent polymer system is introduced, based on cationic and hydrophobic particles (P(nBMA46-co-MMA47-co-DMAEMA90), (PBMD)) with high delivery performance and a pH-responsive block copolymer (poly((N-acryloylmorpholine)-b-(2-(carboxy)ethyl acrylamide)) (P(NAM72-b-CEAm74), PNC)) as shielding system, with PNAM as alternative to PEG. The pH-sensitive polymer design promotes biocompatibility and excellent stability at extracellular conditions (pH 7.4) and also allows endosomal escape and thus high transfection efficiency under acidic conditions. PNC shielded particles are below 200 nm in diameter and showed stable pDNA complexation. Further, interaction with human erythrocytes at extracellular conditions (pH 7.4) was prevented, while acidic conditions (pH 6) enabled membrane leakage. The particles demonstrate transfection in adherent (HEK293T) as well as difficult-to-transfect suspension cells (K-562), with comparable or superior efficiency compared to commercial linear poly(ethylenimine) (LPEI). Besides, the toxicity of PNC-shielded particles was significantly minimized, in particular in K-562 cells and erythrocytes. In addition, a pilot in vivo experiment on bone marrow blood cells of mice that were injected with PNC-shielded particles, revealed slightly enhanced cell transfection in comparison to naked pDNA. This study demonstrates the applicability of cationic hydrophobic polymers for transfection of adherent and suspension cells in culture as well as in vivo by co-formulation with pH-responsive shielding polymers, without substantially compromising transfection performance.Graphical

Tumor Biology; Usefulness of Thermosensitive and pH Sensitive Polymeric Nanoparticles for Tumor Targeting: A Review

Polymeric nanoparticles (PNPs) have attracted the interest of many scientists and have been utilized in an increasing number of fields during the last two decades. The conventional chemotherapeutic agents have poor pharmacokinetic parameters such as non-specific distribution of drugs, the lack of drug specific affinity towards a pathological site, and thus necessitating large dose of a drug to achieve high local concentration in the body leading to systemic toxicity associated with serious side effects. A thorough and precise understanding of tumor microenvironment such as angiogenesis, tumor pH, enhanced permeation and retention (EPR) effect, abnormal lymphatics, multidrug resistance (MDR) and high interstitial fluid pressure, allows designing drug delivery systems that specifically target anti-cancer drugs to tumors. An attempt has been made in this article to highlight the temperature and pH sensitive PNPs, and PNPs with dual and double response to both temperature and pH that have a distinct capacity to target tumors with limited effect on healthy tissues. The stimuli responsive nanoparticles are classified based on their mechanism of response to temperature and pH. Structure of the polymer, methods of drug loading, and characterization of PNPs are elucidated.
 Keywords: Polymeric nanoparticles; pH sensitive polymers; Thermosensitive polymers; Tumor microenvironment; Multidrug resistance; Drug loading.

Development of optimized formulation of liposome using 3-factor Box-Behnken Design

The objective of our present study is to optimize Chitosan coated liposomes formulation by Response surface methodology using 3-factor Box-Behnken Design. Different polymers based liposomes used for delivery of stable pH dependent formulation. Chitosan has been used as a pH sensitive polymer coating to target nanoparticles specifically to tumors which have a slightly acidic pH. Closed membrane system can accommodate amphiphilic or lipophilic drugs in vesicles. The optimized batch was formulated as a liposome delivery system and evaluation was done. To evaluate the unentrapped drug Shimadzu UV-Spectrometry at 228 nm was used and absorbance was noted. Response surface graph was prepared to predict value and the optimized formulation (Chitosan coated liposomes) can be used for loading of bio-active.The values of percent drug entrapment and average vesicle size were presented and found formulation F3&F5 were optimized for further evaluating on basis of particle size and drug loading.

Formulation and Optimization of Colon-Specific Nanoparticles Containing A Herbal Anticancer Agent

Colon cancer is one of the major ailments associated with increased death rate globally. This study aimed to design and optimize a nanoparticulate system for delivering sulforaphane (SFN), a dietary phytochemical with anticancer properties, to the colon. Eudragit S100, a pH-sensitive polymer was utilized to fabricate polymeric nanoparticles for delivering the drug specifically to the colon. The nanoparticles were formulated by nanoprecipitation technique and applied design of experiments (DoE) for optimization and validation. The optimized formulation was characterized for its physicochemical properties, such as particle size, shape, surface morphology, encapsulation efficiency, zeta potential, polydispersity index, in-vitro drug release, and stability at refrigerated conditions. The prepared NPs revealed spherical and smooth surfaces and value of polydispersity index, particle size, zeta potential and encapsulation efficiency were found to be 0.255, 119.46 ± 0.09 nm and -35.68 ± 0.75 mV and 64.17 ± 0.56%, respectively. The in-vitro drug release study showed that the optimized nanoparticles exhibited minimal drug release at pH 1.2 and pH 6.8, but significant and sustained drug release at pH 7.4 corresponded to the colon’s pH. The stability study indicated that the prepared formulation was stable at refrigerated condition for six months. These findings suggest that the developed delivery system could be a promising strategy for effectively encapsulating and delivering the phytochemical anticancer agent to the colon.

Self-oscillating polymer membranes with chemically fueled pore size oscillation mediated by pH-responsive polymer

Soft-matter materials research has considerably evolved in the last decades, mainly by promoting responsive polymer systems. Up to now, the dynamic behavior in materials was always reached by the action of an outside trigger (pH, light, etc..). This constraint has been relieved in a new class of materials that experienced self-oscillation. In this work, the self-regulating pH cycles caused by a chemical oscillator will induce autonomous pH-sensible polymer chain movements at the membrane interface, causing continuous pore-size oscillation cycles and thus a self-oscillating flux. This work involved the functionalisation of polyethersulfone commercial membranes to achieve pore size oscillations. The pH-sensitive polymer, poly(methacrylic acid) (PMAA), was obtained by deprotection of poly(tert-butyl methacrylate) (PtBuMA) synthesized by RAFT polymerization. To adapt this functionalisation to all types of commercial membranes, a thin layer of polydopamine (PDA) was deposited on the top of the membrane, which then allows a Michael-thiol-ene reaction between PDA and thiol-functionalized PMAA, obtained from prior aminolysis of PtBuMA. The functionalisation steps were characterized by XPS, SEM, water contact angle, and permeability measurements. Membranes were then placed in a filtration system containing a chemical pH oscillator to control the PMAA chain conformation through the pH cycle. Water permeation analysis showed a dependence between permeability and PMAA conformation, leading to the conclusion that there is indeed a continuous oscillation in membrane pore size.

Population pharmacokinetics and IVIVC for mesalazine enteric-coated tablets.

Although in-vivo bioequivalence (BE) study serves as a golden standard for establishing interchangeability of oral dosage forms, it remains challenging for products with high inter-subject variability such as mesalazine enteric-coated tablet to fulfil the BE criteria set by regulatory authorities. Mesalazine, as a BCS class IV drug, targets to be delivered to distal ileum or colon with a pH-sensitive polymer coating for the remission of ulcerative colitis. Through population pharmacokinetic (PK) analysis and in-vitro in-vivo correlation (IVIVC) modeling on the dissolution and BE data of a generic enteric-coated product (EM) and its reference Salofalk® 250mg tablet (SM), we for the first time revealed the underlying mechanism of the high inter-subject variability for such delayed-release formulation. It was also noted that the in-vivo start time of absorption (Ts) for EM and SM was positively correlated with their in-vitro lag time (Tlag) under the USP three-stage dissolution condition and reversely correlated with their in-vivo bioavailability. The varied oral bioavailability of mesalazine enteric-coated tablet was mainly due to the varied N-acetyltransferase activities along GI tract. Although such extensive intestinal first-pass metabolism with large individual differences led to a significant variation of mesalazine Cmax (coefficient of variation: 60-63.5%) and AUC0-t (coefficient of variation: 37.5-46.9%), the corresponding variations in the total absorbed mesalazine (mesalazine and its metabolite N-acetyl mesalazine) were significantly reduced by 12 to 45%. Since the BE purpose for mesalazine enteric-coated tablet focused on their comparable safety profiles, total absorbed mesalazine was recommended to be adopted for the development of the IVIVC model and BE evaluation for EM. All in all, our model-based approach has not only successfully identified the key factors that affect the BE of EM to guide its further formulation optimization, but also demonstrated the indispensable role of modeling in the development of generic pharmaceutical product at its early stages.

Trojan pH-Sensitive Polymer Particles Produced in a Continuous-Flow Capillary Microfluidic Device Using Water-in-Oil-in-Water Double-Emulsion Droplets.

A facile and robust microfluidic method to produce nanoparticle-in-microparticle systems (Trojan systems) is reported as a delivery vector for the oral administration of active pharmaceutical ingredients. The microfluidic system is based on two coaxial capillaries that produce monodisperse water-in-oil-in-water (W/O/W) double emulsions in a highly controlled fashion with precise control over the resulting particle structure, including the core and shell dimensions. The influence of the three phase flow rates, pH and drying process on the formation and overall size is evaluated. These droplets are then used as templates for the production of pH-sensitive Trojan microparticles after solvent evaporation. The shell of Trojan microparticles is made of Eudragit®, a methacrylic acid-ethyl acrylate copolymer that would enable the Trojan microparticle payload to first pass through the stomach without being degraded and then dissolve in the intestinal fluid, releasing the inner payload. The synthesis of the pH-sensitive Trojan microparticles was also compared with a conventional batch production method. The payloads considered in this work were different in nature: (1) fluorescein, to validate the feasibility of the polymeric shell to protect the payload under gastric pH; (2) poly(D,L-lactic acid/glycolic acid)-PLGA nanoparticles loaded with the antibiotic rifampicin. These PLGA nanoparticles were produced also using a microfluidic continuous process and (3) PLGA nanoparticles loaded with Au nanoparticles to trace the PLGA formulation under different environments (gastric and intestinal), and to assess whether active pharmaceutical ingredient (API) encapsulation in PLGA is due efficiently. We further showed that Trojan microparticles released the embedded PLGA nanoparticles in contact with suitable media, as confirmed by electron microscopy. Finally, the results show the possibility of developing Trojan microparticles in a continuous manner with the ability to deliver therapeutic nanoparticles in the gastrointestinal tract.

A Gradient pH‐Sensitive Polymer‐Based Antiviral Strategy via Viroporin‐Induced Membrane Acidification (Adv. Mater. 18/2022)

Antiviral Strategies A gradient pH-sensitive (GPS) polymer is developed by Fuping You, Dan Lu, Zhiqiang Lin, and co-workers in article number 2109580. In response to an acidified membrane, the GPS polymer with dye conjugation illuminates, targets, and lyses the envelope of viruses, resulting in leakage of viral nucleic acid and a broad-spectrum activity of the GPS polymer against a variety of viruses.

Delivery of Potential Drugs to The Colon: Challenges and Strategies

Colon-targeted drug delivery systems have been exploited to treat local diseases in the colon, systemic delivery of protein and peptide, and chronotherapeutic drugs. The upper gastrointestinal tract restricts the effective delivery of these drugs. Therefore, several strategies are needed for targeted drugs directly to the colon, such as pH-sensitive polymers, enzyme-sensitive polymers, bacterially degradable polysaccharides, time-dependent polymers, and particulate systems. However, variable physiological conditions of the gastrointestinal tract in individuals cause combinations of these strategies are needed to ensure colonic delivery of the drug. This review presents and discusses several potential drugs and their approaches used to design and develop colon-targeted drug delivery systems for medications with particular characteristics.

Development and Characterization of Eudragit® EPO-Based Solid Dispersion of Rosuvastatin Calcium to Foresee the Impact on Solubility, Dissolution and Antihyperlipidemic Activity.

Poor solubility is the major challenge involved in the formulation development of new chemical entities (NCEs), as more than 40% of NCEs are practically insoluble in water. Solid dispersion (SD) is a promising technology for improving dissolution and, thereby, the bioavailability of poorly soluble drugs. This study investigates the influence of a pH-sensitive acrylate polymer, EPO, on the physicochemical properties of rosuvastatin calcium, an antihyperlipidemic drug. In silico docking was conducted with numerous polymers to predict drug polymer miscibility. The screened-out polymer was used to fabricate the binary SD of RoC in variable ratios using the co-grinding and solvent evaporation methods. The prepared formulations were assessed for physiochemical parameters such as saturation solubility, drug content and in vitro drug release. The optimized formulations were further ruled out using solid-state characterization (FTIR, DSC, XRD and SEM) and in vitro cytotoxicity. The results revealed that all SDs profoundly increased solubility as well as drug release. However, the formulation RSE-2, with a remarkable 71.88-fold increase in solubility, presented 92% of drug release in the initial 5 min. The molecular interaction studied using FTIR, XRD, DSC and SEM analysis evidenced the improvement of in vitro dissolution. The enhancement in solubility of RoC may be important for the modulation of the dyslipidemia response. Therefore, pharmacodynamic activity was conducted for optimized formulations. Our findings suggested an ameliorative effect of RSE-2 in dyslipidemia and its associated complications. Moreover, RSE-2 exhibited nonexistence of cytotoxicity against human liver cell lines. Convincingly, this study demonstrates that SD of RoC can be successfully fabricated by EPO, and have all the characteristics that are favourable for superior dissolution and better therapeutic response to the drug.

Tumor targetable and pH-sensitive polymer nanoparticles for simultaneously improve the Type 2 Diabetes Mellitus and malignant breast cancer

ABSTRACT In the recent study, we have developed novel tumor targetable and pH-sensitive PLGA nanoparticles co-loaded with camptothecin (CPT) and metformin (Metf) to simultaneously improve the Type 2 Diabetes Mellitus (T2DM) and malignant breast cancer. To improve the drug loading efficiency, the hydrophobic CPT was conjugated with PLGA polymer by the pH-sensitive hydrazone bonds (hyd). Then, the Metf was physically loaded into the hydrophobicity inner core of CPT-conjugated PLGA nanocomplex to form the dual drugs-loaded nanoparticles (NP/CPT-Metf). Furthermore, on the surface of NP/CPT-Metf was modified with tumor-homing CGKRK peptides to obtain the tumor targetable and pH-sensitive polymer nanoparticles (CNP/CPT-Metf). It was demonstrated that the developed CNP/CPT-Metf displayed sufficient sensitivity to the weak acidic tumor microenvironment. Besides, excellent ability of CNP/CPT-Metf to mediate accumulation of drugs in cells and tumor tissues finally in turn resulted in a signal enhanced anti-tumor effect. Furthermore, it was demonstrated as well that CNP/CPT-Metf was able of significantly alleviating the type 2 diabetes mellitus in diabetic mice. In summary, the developed multifunctional polymer nanoparticles might represent a promising strategy for simultaneously improve the T2DM and treat malignant breast cancer.

Hydrophilic drug release from electrospun membranes made out of thermo and pH-sensitive polymers

Electrospun fibers of the thermo-and pH sensitive poly(N-vinylcaprolactam-co-acrylic acid) (Poly(NVCL-co-AA) loaded with 10% and 30 wt% caffeine (Caf) were obtained by electrospinning and evaluated as potential drug delivery systems. Caffeine was used as a hydrophilic drug model, and poly(NVCL-co-AA) containing either 20 or 30 mol% AA was used as a carrier. The fibers morphology, as well as, their interaction with caffeine, were studied using different analytical techniques. The cytotoxicity of the different obtained fibers was evaluated by cell viability assays using 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) and mouse embryonic fibroblasts cell line (MEF cells). Caffeine release was studied at temperatures of 25 °C and 42 °C and pH of 1.2 and 7.4. Beadless copolymer fibers with diameters ranging from 1 μm to 2 μm were obtained. The addition of caffeine, which was in crystalline form after being encapsulated in the fibers, resulted in an increase of fiber diameter. The obtained membranes were found to be not cytotoxic. The entrapment of caffeine was greater for the copolymer containing 30 mol% AA due to a greater affinity of AA to caffeine. At a pH of 1.2 and at both temperatures of 25 °C and 42 °C, as well as, at a pH of 7.4 and a temperature of 42 °C, a Fickian diffusion mechanism for all copolymer fiber mats was observed. At a pH of 7.4 and 25 °C the release profile showed a high rate and followed a zero-order model, due to the fast dissolution of caffeine in water. These results indicated that thermo-and pH-sensitive poly(NVCL-co-AA) are promising candidates for controlled release of hydrophilic drugs.

Microfluidic-Assisted Fabrication of Dual-Coated pH-Sensitive Mesoporous Silica Nanoparticles for Protein Delivery.

Microfluidics has become a popular method for constructing nanosystems in recent years, but it can also be used to coat other materials with polymeric layers. The polymeric coating may serve as a diffusion barrier against hydrophilic compounds, a responsive layer for controlled release, or a functional layer introduced to a nanocomposite for achieving the desired surface chemistry. In this study, mesoporous silica nanoparticles (MSNs) with enlarged pores were synthesized to achieve high protein loading combined with high protein retention within the MSN system with the aid of a microfluidic coating. Thus, MSNs were first coated with a cationic polyelectrolyte, poly (diallyldimethylammonium chloride) (PDDMA), and to potentially further control the protein release, a second coating of a pH-sensitive polymer (spermine-modified acetylated dextran, SpAcDEX) was deposited by a designed microfluidic device. The protective PDDMA layer was first formed under aqueous conditions, whereby the bioactivity of the protein could be maintained. The second coating polymer, SpAcDEX, was preferred to provide pH-sensitive protein release in the intracellular environment. The optimized formulation was effectively taken up by the cells along with the loaded protein cargo. This proof-of-concept study thus demonstrated that the use of microfluidic technologies for the design of protein delivery systems has great potential in terms of creating multicomponent systems and preserving protein stability.

Charge Conversion Polymer-Liposome Complexes to Overcome the Limitations of Cationic Liposomes in Mitochondrial-Targeting Drug Delivery.

Mitochondrial-targeting therapy is considered an important strategy for cancer treatment. (3-Carboxypropyl) triphenyl phosphonium (CTPP) is one of the candidate molecules that can drive drugs or nanomedicines to target mitochondria via electrostatic interactions. However, the mitochondrial-targeting effectiveness of CTPP is low. Therefore, pH-sensitive polymer–liposome complexes with charge-conversion copolymers and CTPP-containing cationic liposomes were designed for efficiently delivering an anti-cancer agent, ceramide, into cancer cellular mitochondria. The charge-conversion copolymers, methoxypoly(ethylene glycol)-block-poly(methacrylic acid-g-histidine), were anionic and helped in absorbing and shielding the positive charges of cationic liposomes at pH 7.4. In contrast, charge-conversion copolymers became neutral in order to depart from cationic liposomes and induced endosomal escape for releasing cationic liposomes into cytosol at acidic endosomes. The experimental results reveal that these pH-sensitive polymer–liposome complexes could rapidly escape from MCF-7 cell endosomes and target MCF-7 mitochondria within 3 h, thereby leading to the generation of reactive oxygen species and cell apoptosis. These findings provide a promising solution for cationic liposomes in cancer mitochondrial-targeting drug delivery.

Preparation of stable enteric folic acid-loaded microfiber using the electrospinning method.

Objective(s):Folic acid is an essential vitamin, labile to hydrolysis in the acidic environment of the stomach with low water solubility and bioavailability. In order to solve these problems, enteric oral folic acid-loaded microfibers with a pH-sensitive polymer by electrospinning method were prepared.Materials and Methods:Electrospinning was performed at different folic acid ratios and voltages. Fibers were evaluated in terms of mechanical strength, acidic resistance, and drug release. Additionally, DSC (Differential Scanning Calorimetry), FTIR (Fourier-transform infrared spectroscopy), and XRD (X-ray diffraction) analyses were performed on the optimal formulation. Results:Drug ratio and voltage had a considerable effect on fibers’ entrapment efficiency, acid resistance, and mechanical strength. Based on the obtained results, the optimum formulation containing 1.25% of the drug/polymer was prepared at 18 kV. The entrapment efficiency of the optimal sample was above 90% with an acid resistance of higher than 70%. The tensile test confirmed the high mechanical properties of the optimum microfiber. DSC and XRD tests indicated that folic acid was converted to an amorphous form in the fiber structure and the FTIR test confirmed the formation of a chemical bond between the drug and the polymer. The release of the drug from the optimal fiber was about 90% in 60 min.Conclusion:In conclusion, the optimal formulation of folic acid with proper mechanical properties can be used as a candidate dosage form for further bioavailability investigations.

Self-propelled Janus micromotors for pH-responsive release of small molecule drug

Oral administration of drugs has received significant attention in the last 1, 2 decades, as it is the most comfortable and painless administration route, which leads to high patient compliance. Although oral delivery of drugs shows positive effects in patients, several hurdles must be overcome such as enzymatic degradation, large pH-variations found throughout the gastrointestinal (GI) tract, and continuous mucus secretion. We have studied biocompatible non-toxic micromotors as promising man-made microdevices for targeted furosemide release. Micromotors are micro-scale autonomous entities that can perform various tasks in the GI tract as a result of their impressive motion abilities. Their directional motion makes them ideal candidates to bring the necessary drug dosage to where it is needed. Herein, the micromotors were loaded for the first time with furosemide and coated with pH-sensitive polymer Eudragit® L100 using ultrasonic spray coating technique in order to achieve targeted drug delivery and pH-responsive release. Coherent anti-Stokes Raman scattering spectroscopy (CARS) was used for visualizing drug loading efficiency on the surface of micromotors. In vitro drug release was evaluated under acidic and neutral pH chemical environments and obtained results confirm their function as pH-sensitive microdevices for a drug release.

Potent adjuvant effect elicited for tumor immunotherapy by a liposome conjugated pH-sensitive polymer and dendritic cell-targeting Toll-like-receptor ligand

The generation of DCs with augmented functions is a strategy for obtaining satisfactory clinical outcomes in tumor immunotherapy. We developed a novel synthetic adjuvant comprising a liposome conjugated with a DC-targeting Toll-like-receptor ligand and a pH-sensitive polymer for augmenting cross-presentation. In an in vitro study using mouse DCs, these liposomes were selectively incorporated into DCs, significantly enhanced DC function and activated immune responses to present an epitope of the incorporated antigen on the major histocompatibility complex class I molecules. Immunization of mice with liposomes encapsulating a tumor antigen significantly enhanced antigen-specific cytotoxicity. In tumor-bearing mice, vaccination with liposomes encapsulating a tumor antigen elicited complete tumor remission. Furthermore, vaccination significantly enhanced cytotoxicity, targeting not only the vaccinated antigen but also the other antigens of the tumor cell. These results indicate that liposomes are an ideal adjuvant to develop DCs with considerably high potential to elicit antigen-specific immune responses; they are a promising tool for cancer therapy with neoantigen vaccination.

Amphiphilic pH-sensitive polypeptides for siRNA delivery

The effective delivery of nucleic acid therapeutics into tumor cells is of great importance in terms of cancer gene therapy. Successful application of siRNAs is restricted by the requirement to overcome several biological barriers, i.e. cell membrane penetration, endosomal escape, enzymatic degradation in cytosol, etc. Cationic polymers are promising delivery systems due to their biodegradability and effective binding with siRNA. A key characteristic of the particle trafficking into the cell is a noticeable change in pH during this process. This change can be used as a natural stimulus for pH-sensitive polymer particles. Such polymers are able to buffer the environment of a late endosome that leads to an abnormal flow of ions and water followed by endosomal swelling and disrupt and quick escape of the carriers into a cytoplasm. In present work, we synthesized a series of amphiphilic positively charged biocompatible pH-sensitive polypeptides forming polyplexes with nucleic acids. Four amino acids were used to compose the delivery systems, namely l-lysine, l-glutamic acid, l-phenylalanine and l-histidine. The number and the ratio of amino acids were varied in order to establish the optimal composition. The characteristics of polypeptides were studied by 1H NMR spectroscopy, high performance liquid chromatography and static light scattering. All synthesized polypeptides tended to a self-assembly in aqueous media and formed nanoparticles with hydrodynamic diameters ranging from 140 to 360 nm. The formation of polyplexes with short double-stranded oligonucleotides as a physicochemical siRNA model as well as the release of cargo in buffer media mimicking lysosome (pH∼5) and cytosol or bloodstream (pH 7.4) were studied. Cellular uptake of the particles was efficient and their cytotoxicity was negligible. Successful RNAi-mediated down-regulation of GFP gene expression was revealed in MDA-MB-231/GFP breast cancer cells. The amphiphilic polypeptides obtained can be considered as promising non-viral candidates for siRNA delivery.

Composition of Piperine with Enteric-Coated Chitosan Microspheres Enhances the Transepithelial Permeation of Curcumin in Sheep Intestinal Mucosa and Caco-2 Cells

Abstract Objectives The purpose of this study was to investigate the efficacy of enteric-coated chitosan microspheres with herbal bioenhancer, piperine, as a suitable composition for improving the permeation of curcumin through biological membranes using suitable ex vivo models. Material and Methods Chitosan microspheres of curcumin and piperine were prepared by an emulsion cross-linking method using glutaraldehydes the cross-linking agent and characterized for size, shape, entrapment efficiency, mucoadhesion, and in vitro release. The effect of piperine on the permeation of curcumin through excised sheep intestinal mucosa and Caco-2-cell monolayer was investigated. Statistical Analysis The data from permeation studies were analyzed by Student's t-test using Statistical Package for the Social Sciences (SPSS) software (SPSS, Chicago, IL, United States) with p-values <0.05 indicating statistical significance. Results The formulations showed mucoadhesion for a period of more than 6 hours which was influenced by the chitosan content. The rate of drug release of uncoated formulation followed first-order kinetics, and the mechanism of release was non-Fickian transport. Optimized formulation was coated with a pH-sensitive polymer, Eudragit S-100, by a solvent evaporation technique in different concentrations and evaluated for ex vivo permeation through sheep intestinal mucosa and Caco-2-cell monolayer. Scanning electron microscopy images of the optimized coated formulation showed spherical particles with smooth surfaces. The calculated permeation flux and permeability coefficient of curcumin from microspheres were at least 20% greater in the presence of piperine through the intestinal mucosa and 30% through the Caco-2-cell monolayer model. The permeability coefficient of curcumin from microspheres with piperine was 1.93 × 10 to 5 cm/sec and significantly greater (p < 0.05) than that of microspheres devoid of piperine and from aqueous dispersion (p < 0.005). Conclusion The study confirmed the contribution of piperine and mucoadhesive microspheres toward improved permeation of curcumin through biological membranes, thereby providing an approach that has the potential of increasing transport through intestinal epithelial cells and possibly enhancing the oral bioavailability of this drug.