Chemically modified polyacrylamide-g-guar gum-based crosslinked anionic microgels as pH-sensitive drug delivery systems: preparation and characterization

PEG-PCL based micelle hydrogels as oral docetaxel delivery systems for breast cancer therapy

In this study, a composite drug delivery system was developed and evaluated for oral delivery of docetaxel: docetaxel-loaded micelles in pH-responsive hydrogel (DTX-micelle-hydrogel). Docetaxel was successfully loaded in micelles with small particle size of 20 nm and high drug loading of 7.76%, which contributed to the drug absorption in the intestinal tract. The experiments of cytotoxicity on 4T1 cells demonstrated the effective antitumor activity of DTX micelles. Meanwhile, a pH-responsive hydrogel was synthesized and optimized for incorporating the docetaxel micelles. The pH-responsiveness and reversibility of the hydrogel were investigated under the pH conditions of the gastrointestinal tract. Furthermore, the DTX-micelle-hydrogel system showed much quicker diffusion of micelles in simulated intestinal fluid than in simulated gastric fluid, which was mainly caused by the change of pH value. The docetaxel released from the micelle-hydrogel system quite slowly, so it had little influence on the absorption of DTX micelles in small intestine. More important, the pharmacokinetic study revealed that the DTX-micelle-hydrogel significantly improved the oral bioavailability of docetaxel (75.6%) about 10 times compared to DTX micelles, and this increase in bioavailability was probably due to the small intestine targeting release of the pH-responsive hydrogel. Consequently, the oral DTX-micelle-hydrogel system was effective in inhibiting tumor growth in subcutaneous 4T1 breast cancer model, and decreased systemic toxicity compared with intravenous treatment. The apoptosis cells in the immunofluorescent studies and the proliferation-positive cells in the immunohistochemical studies were also consistent with the results. Therefore, the DTX-micelle-hydrogel system might be a promising candidate oral drug for breast cancer therapy.

Development of poly(N-isopropylacrylamide)/alginate copolymer hydrogel-grafted fabrics embedding of berberine nanosuspension for the infected wound treatment

In the present study, a novel hydrogel-grafted fabrics embedding of berberine nanosuspension was developed for the treatment of infected wound. Hydrogel-grafted fabric was prepared by graft copolymerization of N-isopropylacrylamide and alginate using ceric ammonium nitrate as initiator. Berberine nanosuspension was prepared and embedded in the hydrogel-grafted fabrics to achieve sustained drug release. The prepared hydrogel-grafted fabrics embedding of berberine nanosuspension was characterized by FT-IR spectroscopy, scanning electron microscopy, and swelling degree studies. Fourier transform infrared spectroscopy revealed that berberine was embedded into the matrix of hydrogel-grafted fabrics, rather than on the surface. Scanning electron microscopy showed that a thin hydrogel layer was formed on the surface of nonwoven fibers. The swelling study showed that hydrogel-grafted fabric had water absorbing characteristic with reversible temperature sensitivity. The drug release study demonstrated that hydrogel-grafted fabrics can be used as a sustained drug delivery system of hydrophobic compounds. The berberine nanosuspension embedded hydrogel-grafted fabric was further investigated in an animal infected wound model and was found to be a very promising wound healing dressing for the treatment and healing of infected wounds.

Design, development, and optimization of polymeric based-colonic drug delivery system of naproxen

The aim of present investigation deals with the development of time-dependent and pH sensitive press-coated tablets for colon specific drug delivery of naproxen. The core tablets were prepared by wet granulation method then press coated with hydroxypropyl cellulose (HPC) or Eudragit RSPO : RLPO mixture and further coated with Eudragit S-100 by dip immerse method. The in vitro drug release study was conducted in different dissolution media such as pH 1.2, 6.8, and 7.4 with or without rat caecal content to simulate GIT conditions. Surface morphology and cross-sectional view of the tablets were visualized by scanning electron microscopy (SEM). All prepared batches were in compliance with the pharmacopoeial standards. The tablets which are compression coated with HPC followed by Eudragit S-100 coated showed highest in vitro drug release of 98.10% in presence of rat caecal content. The SEM of tablets suggested that the number of pores got increased in pH 7.4 medium followed by dissolution of coating layer. The tablets coat erosion study suggested that the lag time depends upon the coating concentrations of polymers. A time-dependent hydrophilic polymer and pH sensitive polymer based press-coated tablets of naproxen were promising delivery for colon targeting.

"Development and evaluation of sodium alginate-polyacrylamide graft-co-polymer-based stomach targeted hydrogels of famotidine"

In the present study, grafting technology has been used to develop novel grafted hydrogel beads as controlled drug delivery carriers. The chemical crosslinking and grafting of polyacrylamide onto sodium alginate has been found to be efficient method for the development of new polymeric carrier. The successful crosslinking has been confirmed by Fourier transformed infrared spectroscopy, thermogravimetric analysis, and elemental analysis. The polymeric network of sodium alginate-co-polyacrylamide (NaAlg-g-PAM) has been interlinked by covalent and hydrogen bonds which also strength the gel network. Simple ionotropic gelation method has been used for the preparation of NaAlg-g-PAM hydrogel beads. Its swelling and gelation were dependent on monomer and crosslinker concentrations. Entrapment of the drug moiety (famotidine; an antiulcer drug) within the grafted beads has been confirmed by X-ray powder diffraction and differential scanning calorimetry. More than 75% of drug loading in beads occurred with the increase of monomer and crosslinker concentration. In vitro drug release was found to be sustained up to the 12 h with 80% drug release.

Novel pH- and temperature-responsive blend hydrogel microspheres of sodium alginate and PNIPAAm-g-GG for controlled release of isoniazid

This paper reports the preparation and characterization of novel pH- and thermo-responsive blend hydrogel microspheres of sodium alginate (NaAlg) and poly(N-isopropylacrylamide)(PNIPAAm)-grafted-guar gum (GG) i.e., PNIPAAm-g-GG by emulsion cross-linking method using glutaraldehyde (GA) as a cross-linker. Isoniazid (INZ) was chosen as the model antituberculosis drug to achieve encapsulation up to 62%. INZ has a plasma half-life of 1.5 h, whose release was extended up to 12 h. Fourier transform infrared spectroscopy was used to confirm the grafting reaction and chemical stability of INZ during the encapsulation. Differential scanning calorimetry was used to investigate the drug's physical state, while powder X-ray diffraction confirmed the molecular level dispersion of INZ in the matrix. Scanning electron microscopy confirmed varying surface morphologies of the drug-loaded microspheres. Temperature- and pH-responsive nature of the blend hydrogel microspheres were investigated by equilibrium swelling, and in vitro release experiments were performed in pH 1.2 and pH 7.4 buffer media at 37°C as well as at 25°C. Kinetics of INZ release was analyzed by Ritger-Peppas empirical equation to compute the diffusional exponent parameter (n), whose value ranged between 0.27 and 0.58, indicating the release of INZ follows a diffusion swelling controlled release mechanism.

Chitosan matrix with three dimensionally ordered macroporous structure for nimodipine release

Three dimensionally ordered macroporous (3DOM) chitosan (3D-CS) matrix with interconnected pores in the nanometer range was developed as a drug carrier for the first time. 3D-CS was prepared using a template-assisted assembly and characterized by SEM, TGA, N(2) adsorption and FT-IR. As a model drug, nimodipine (NMDP) was incorporated into the pores of 3D-CS matrix. The solid state properties of NMDP-loaded samples were characterized by SEM, XRD, DSC and FT-IR. Dissolution studies showed that release behavior of the drug was markedly affected by the particle size of the matrix. With a relatively small matrix particle size, formulations of NMDP-3D-CS-0.5 and NMDP-3D-CS-1 exhibited rapid release patterns. However, on increasing the amount of carrier, release rate of the drug decreased. The pH-dependent slow-release characteristic of 3D-CS matrix delivery system was demonstrated by investigating the release behavior of NMDP at different pH values.

Stimuli-responsive polymers and their applications in nanomedicine

This review focuses on smart nano-materials built of stimuli-responsive (SR) polymers and will discuss their numerous applications in the biomedical field. The authors will first provide an overview of different stimuli and their corresponding, responsive polymers. By introducing myriad functionalities, SR polymers present a wide range of possibilities in the design of stimuli-responsive devices, making use of virtually all types of polymer constructs, from self-assembled structures (micelles, vesicles) to surfaces (polymer brushes, films) as described in the second section of the review. In the last section of this review the authors report on some of the most promising applications of stimuli-responsive polymers in nanomedicine. In particular, we will discuss applications pertaining to diagnosis, where SR polymers are used to construct sensors capable of selective recognition and quantification of analytes and physical variables, as well as imaging devices. We will also highlight some examples of responsive systems used for therapeutic applications, including smart drug delivery systems (micelles, vesicles, dendrimers...) and surfaces for regenerative medicine.

Preparação de nanopartículas poliméricas a partir da polimerização de monômeros: parte I

Nanopartículas poliméricas produzidas a partir de polímeros sintéticos, como copolímeros do ácido metacrílico, ésteres acrílicos ou metacrílicos, têm sido amplamente utilizadas na área farmacêutica para encapsulação de princípios ativos. Essas nanopartículas apresentam as vantagens de proteção, liberação controlada, melhor biodisponibilidade e menor toxicidade, proporcionando maior conforto aos pacientes e adesão ao tratamento. A produção das nanopartículas (nanocápsulas e nanosferas) por polimerização de monômeros é revisada e descrita neste artigo, evidenciando os parâmetros tecnológicos que interferem nas características físico-químicas das nanopartículas, como a solubilidade do princípio ativo, o volume e pH do meio de polimerização, a massa molar e concentração do monômero e a natureza e concentração do tensoativo.

Novel interpenetrated polymer network microbeads of natural polysaccharides for modified release of water soluble drug: in-vitro and in-vivo evaluation

OBJECTIVES

The objective of this work was to prepare novel interpenetrating polymer network (IPN) microbeads of tamarind seed polysaccharide and sodium alginate for controlled release of the water soluble drug, diltiazem hydrochloride.

METHODS

The diltiazem-Indion 254(®) (a cation exchange resin) complex was prepared and the resulting complex was entrapped within IPN microbeads prepared by ionotropic gelation and covalent crosslinking. Microbeads were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) analyses, and evaluated for swelling, in-vitro release and preclinical pharmacokinetics.

KEY FINDINGS

The unformulated drug showed complete dissolution within 60min, while drug release from diltiazem-ion-exchange resin complex was extended for 2.5h but IPN microbeads extended the release for longer period. The ionically crosslinked microbeads released the drug for 6h, while dual crosslinked microbeads extended the release for 9h. The microbeads containing a higher amount of glutaraldehyde released the drug very slowly. The results of in-vivo pharmacokinetics of pure drug and drug-loaded IPN microbeads showed that the microbeads demonstrated prolonged release supporting the findings of in-vitro studies.

CONCLUSIONS

Prepared IPN microbeads showed prolonged in-vitro and in-vivo release for diltiazem, indicating that this IPN would be a versatile delivery system for water soluble drugs.

pH-responsive interpenetrating network hydrogel beads of poly(acrylamide)-g-carrageenan and sodium alginate for intestinal targeted drug delivery: synthesis, in vitro and in vivo evaluation

In the present work, we synthesized pH-responsive interpenetrating network (IPN) hydrogel beads of polyacrylamide grafted κ-carrageenan (PAAm-g-CG) and sodium alginate (SA) for targeting ketoprofen to the intestine. The PAAm-g-CG was synthesized by free radical polymerization followed by alkaline hydrolysis under nitrogen gas. The PAAm-g-CG was characterized by elemental analysis, FTIR spectroscopy and thermogravimetric analysis (TGA). The drug-loaded IPN hydrogel beads were prepared by simple ionotropic gelation/covalent crosslinking method. The amorphous nature of drug in the beads was confirmed by differential scanning calorimetry and X-ray diffraction studies. The spherical shape of the beads was confirmed by scanning electron microscopic analysis. The beads exhibited ample pH-responsive behavior in the pulsatile swelling study. The ketoprofen release was significantly increased when pH of the medium was changed from acidic to alkaline. The beads showed maximum of 10% drug release in acidic medium of pH 1.2, and about 90% drug release was recorded in alkaline medium of pH 7.4. Stomach histopathology of albino rats indicated that the prepared beads were able to retard the drug release in stomach leading to the reduced ulceration, hemorrhage and erosion of gastric mucosa.

Xylan-rich hemicelluloses-graft-acrylic acid ionic hydrogels with rapid responses to pH, salt, and organic solvents

Exploitation of biomaterials derived from renewable resources is an important approach to address environmental and resource problems in the world today. In this paper, novel ionic hydrogels based on xylan-rich hemicelluloses were prepared by free radical graft copolymerization of acrylic acid (AA) and xylan-rich hemicelluloses (XH) by using N,N-methylene-bis(acrylamide) (MBA) as cross-linker and ammonium persulfate/N,N,N',N'-tetramethylethylenediamine (APS/TMEDA) as redox initiator system. The network characteristics of the ionic hydrogels were investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), as well as by determination of mechanical properties, swelling, and stimuli responses to pH, salts, and organic solvents. The results showed that an increase in the MBA/XH or AA/XH ratio resulted in higher cross-linking density of the network and thus decreased the swelling ratio. Expansion of the network hydrogels took place at high pH, whereas shrinkage occurred at low pH or in salt solutions as well as in organic solvents. The ionic hydrogels had high water adsorption capacity and showed rapid and multiple responses to pH, ions, and organic solvents, which may allow their use in several areas such as adsorption, separation, and drug release systems.

Evaluation of anti-GERD activity of gastro retentive drug delivery system of itopride hydrochloride

The present work describes the formulation and evaluation of the gastroretentive system of Itopride hydrochloride. In this research, we have formulated floating hydrogel-based microspheres employing calcium carbonate (CaCO(3)) as a gas forming agent dispersed in alginate matrix. In vitro characterizations such as drug content, particle size, and drug release were carried out. GI motility was determined by administration of charcoal meal to rats. Results demonstrated that prepared microspheres were spherical in shape with smooth surface, good loading efficiency, and excellent buoyancy. The gastro retentive dosage form of itiopride demonstrated significant antacid, anti-ulcer, and anti-GERD activity after 12 hours in comparison with the conventional dosage form.

Evaluation of a matrix tablet prepared with polyacrylamide-g-sodium alginate co-polymers and their partially hydrolyzed co-polymers for sustained release of diltiazem hydrochloride

Diltiazem hydrochloride (DTZ) matrix tablets were prepared using polyacrylamide-grafted sodium alginate (PAam-g-SA) co-polymers having different percentages of grafting and their partially hydrolyzed products with a view to achieve sustained release of the highly water-soluble drug. PAam-g-SA co-polymers having different percentages of grafting were synthesized by free radical polymerization using acrylamide (Aam) as monomer and ammonium persulphate (APS) as initiator, and the resulting co-polymers were subjected to alkaline hydrolysis to produce their corresponding partially hydrolyzed co-polymers. Matrix tablets of DTZ were prepared by wet granulation using either PAam-g-SA co-polymers or partially hydrolyzed PAam-g-SA co-polymers. The effect of percentage grafting, drug load and calcium gluconate (CG), used as excipient, was studied in simulated gastrointestinal fluid. While the tablets prepared using the co-polymer having higher percentages of grafting provided faster drug release (100% in 5.5 h), the tablets prepared with the corresponding hydrolyzed co-polymer released the drug slowly (71% in 12 h). This behaviour in release appeared to be controlled by the relative magnitude of the viscosity and the swelling capacity of the copolymers. Moreover, increase in drug load tended to decrease the drug release from all types of tablets and increase in the amount of CG increased the drug release. FT-IR and DSC studies revealed the absence of any interaction between the drug and the co-polymers. The matrix tablet made of partially hydrolyzed graft co-polymer having the highest percentage of grafting provided the most sustained release of the drug.

Modulation of biological processes in the nucleus by delivery of DNA oligonucleotides conjugated with gold nanoparticles

The development of a method that can efficiently deliver nucleic acids into the nucleus of living systems remains one of the key challenges for experimental and therapeutic use of nonbiological gene delivery agents. In the current study, we demonstrate a functionalized gold nanoparticle (AuNP) that can serve as a universal carrier for the delivery of DNA oligonucleotides (oligos) into the nucleus. We designed various types of DNA oligos to redirect alternative splicing of pre-mRNAs, such as MCL-1 and BCL-6, and to sequester transcriptional factors, including estrogen receptor α and p53. We successfully delivered the oligos into the nucleus, resulting in the targeted effects. In addition, injection of the antisense DNAs into a xenograft tumor in a mouse model system resulted in inhibited development of the tumor by redirecting the alternative splicing of the pre-mRNA. Our findings show that these nanoconjugates efficiently load and deliver antisense DNAs to redirect gene splicing or double-stranded DNAs to decoy gene transcription by transcriptional factors into mammalian cells and in vivo animals. Therefore, our lego-like AuNP gene delivery system can be used universally to control different biological processes by modulating nuclear gene expression events in living systems.

Gastroretentive drug delivery system of acyclovir-loaded alginate mucoadhesive microspheres: formulation and evaluation

In the present study, mucoadhesive alginate microspheres of acyclovir were prepared to prolong the gastric residence time using a simple emulsification phase separation technique. The particle size of drug-loaded formulations was measured by SEM and the particle size distribution was determined using an optical microscope and mastersizer. The release profile of acyclovir from microspheres was examined in simulated gastric fluid (SGF pH 1.2). The particles were found to be discreet and spherical with the maximum particles of an average size (70.60 ± 2.44 µm). The results indicated that the mean particle size of the microspheres increased with an increase in the concentration of polymer and decreased with increase in stirring speed. The entrapment efficiency was found to be in the range of 51.42-80.46%. The concentration of the calcium chloride (% w/v) of 10% and drug-polymer ratio of 1:4 resulted in an increase in the entrapment efficiency and the extent of drug release. The optimized alginate microspheres were found to possess good mucoadhesion (66.42 ± 1.01%). The best fit model with the highest regression coefficient values (R²) was predicted by Peppas model (0.9813). In Gamma scintigraphy analysis, the section of GIT was critically analyzed and much differentiation was present at each time point after oral administration, which revealed that the optimized formulation demonstrated gastroretention in vivo for more than 4 h, which revealed that optimized formulation could be a good choice for gastroretentive systems.