pH-sensitive Composite Hydrogel Research Articles

Synthesis, Characterization, and Investigation of Doxorubicin Drug Release Properties of Poly(acrylamide-co-acrylic Acid/Maleic Acid)- Hydroxyapatite Composite Hydrogel.

Hydroxyapatite and its derivatives have been used for a lot of applications. One of them is drug release studies. Due to its low adhesion strength and lack of the strength and durability required for load-carrying applications, there is a need to improve the properties of hydroxyapatite. For this aim, the most important factors are increasing pH sensitivity and preventing coagulation. Mixing it with multifunctional polymers is the best solution. The main objectives are: 1- preparing poly(acrylamide-co-acrylic acid/maleic acid)- hydroxyapatite (PAm-co-PAA/PMA-HApt), 2- assessment of (PAm-co-PAA/PMA-HApt) and dox-loaded poly(acrylamide-co-acrylic acid/maleic acid) (Dox-(PAm-co-PAA/PMA-HApt)) composite hydrogels, and 3- elucidating the difference in behavior of drug release studies between hydroxyapatite (HApt) and poly(acrylamide-co-acrylic acid/maleic acid) composite hydrogels. A composite of PAm-co-PAA/PMA-HApt was prepared by direct polymerization of acrylamide-co-acrylic acid/maleic acid in a suspension of HApt. The drug loading and release features of PAm-co-PAA/PMA-HApt and HApt were then investigated for doxorubicin (dox) release. Using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TG/DTA), this unique composite hydrogel has been physicochemically investigated. Also, a colorimetric assay was used to assess the in vitro biocompatible support and anticancer activity of HApt and the newly developed composite hydrogel XTT (2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide) assay. According to the results of drug release studies of this new material, it is pH sensitive, and PAm-co-PAA/PMA-HApt demonstrated a faster release than HApt at 37 °C in the acidic solution of pH 4.5 than in the neutral solution of pH 7.4. The XTT assay outcomes also demonstrated the biocompatibility of PAm-co-PAA/PMA-HApt and HApt and the cytotoxic effect of dox-loaded PAm-co-PAA/PMA-HApt. It should be inferred that the drug release profile was improved at pH 4.5 by the newly produced pH-sensitive composite hydrogel.

Fabrication of KDF-loaded chitosan-oligosaccharide-encapsulated konjac glucomannan/sodium alginate/zeolite P microspheres with sustained-release antimicrobial activity

Potassium diformate(KDF) is a non-antibiotic growth promoter. To improve the utilization of KDF in the intestinal tract, P-type zeolite molecular sieve (zeolite P) was used as the drug-binding effector of KDF and was encapsulated in sodium alginate (ALG)/konjac glucomannan (KGM)/chitosan oligosaccharide (COS) composite hydrogel microspheres to prepare environment friendly, intelligent and pH-sensitive composite hydrogel microspheres for controlling the release of KDF. The composite hydrogel microspheres were characterized using XRD, FT-IR, TGA, and SEM. In addition, the swelling behavior of the composite hydrogel microspheres in three buffered media was determined. Thus, the phase composition, structural characteristics, thermal stability, apparent morphology and swelling properties were determined. Results indicated that the composite hydrogel microspheres possessed pH sensitivity, compatibility and porous 3D network structure. Furthermore, ALG formed polyelectrolyte complexes with COS, providing the composite hydrogel microspheres a complete three-dimensional network structure. The embedded network structure of zeolite P, which limited the size of the inner capsule, assisted in improving the thermal stability, and allowed expansion and controlled release of KDF. Under a simulated gastrointestinal environment, the in vitro release conformed to a good pH-sensitive drug release pattern and prevented premature release of KDF in the gastric juice. In the in vitro antibacterial test, the maximum inhibition rate of the antibacterial agent against Escherichia coli, Staphylococcus aureus and Bacillus subtilis were 96.63%, 93.81% and 93.31%, respectively, indicating its considerable potential as an intestinal antibacterial.

Novel pH sensitive composite hydrogel based on functionalized chitosan/clay for the controlled release of a calcium channel blocker

The concept of novel drug delivery systems aims at achieving systematically improved therapeutic success for drugs including those that have limited use because of toxicity, uneven distribution pattern, stability and formulation of difficulties. The paper reveals the potential uses of novel hybrids of oleic acid-g-chitosan and montmorillonite (OA-g-CS/MMT) in controlled drug delivery applications. A calcium channel blocker is a chemical that disrupts the movement of calcium (Ca2+) through calcium channels. The calcium channel blocker used for the present investigation is diltiazem hydrochloride, which forms a class three antianginal drug, and a class IV antiarrhythmic. The drug-loaded novel composites have been prepared by solvent casting and freeze drying of the grafted polymer solution. Drug release was monitored by changing time, percentage of drug loading and pH of the medium. It was observed that the release was much more pronounced in the basic medium than in the acidic medium. The maximum release of drug from OA-g-CS/MMT in both gastric and intestinal fluids was observed within a time period of 12 h.

Preparation, Characterization, and Drug-Release Behaviors of a pH-Sensitive Composite Hydrogel Bead Based on Guar Gum, Attapulgite, and Sodium Alginate

A novel guar gum-g-poly (acrylic acid)/attapulgite/sodium alginate (GG-g-PAA/APT/SA) composite hydrogel bead with excellent pH sensitivity was prepared via a facile ionic gelation approach and characterized by FTIR and SEM techniques. The effect of APT content on the encapsulation efficiency (EE), swelling ratio, and drug release behaviors of the beads was investigated and the in-vitro release kinetics were also evaluated using diclofenac sodium (DS) as the model drug. The results indicate that the burst release effect of DS drug was eliminated due to the incorporation of APT, and the DS cumulative release was clearly decreased with increasing the APT content.

A pH-sensitive composite hydrogel based on sodium alginate and medical stone: Synthesis, swelling, and heavy metal ions adsorption properties

New pH-sensitive composite hydrogels were synthesized by free-radical graft copolymerization among sodium alginate (NaAlg), sodium acrylate (NaA), and medical stone (MS). Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), tronsmission electron microscopy (TEM), and thermogravimetric analysis (TGA) analyses confirmed that NaA was grafted onto the NaAlg chains and MS participate in polymerization by its active silanol groups, and the surface morphologies and thermal stability was clearly improved after incorporating MS. The swelling capacity and rate of the hydrogel were clearly enhanced by introducing MS, and the intriguing deswelling in gelatin solution and “overflowing” behaviors in dimethyl sulfoxide (DMSO) and glycerin solutions were observed. In addition, the composite hydrogels exhibited excellent adsorption capacity on heavy metal ions, which enhanced the adsorption of Ni2+, Cu2+, Zn2+ and Cd2+ ions by 10.4, 8.0, 23.0, and 14.3 fold compared to active carbon (AC), and by 17.3, 16.0, 38.3 and 23.8 fold compared to MS, respectively. The biopolymer-based composite hydrogel can be used as a potential water-saving material and candidate of AC for heavy metal removal. Open image in new window

Synthesis and characterization of a novel pH-controllable composite hydrogel for anticancer drug delivery

A novel pH-sensitive composite hydrogel (CH) namely 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) grafted N-maleoylchitosan (MACTS) intercalated montmorillonite has been synthesized by in situ intercalation graft copolymerization of AMPS with MACTS intercalated MMT (MACTS/MMT) by using potassium persulfate (KPS) as a free radical initiator, in the presence of N,N-methylenebisacrylamide (MBA) as a crosslinking agent. A hydrophilic anticancer drug, 5-fluorouracil (5-FLU), has been chosen to investigate the loading and release properties of the CH. The CH formation and 5-FLU loading ability of CH have been confirmed by FTIR. X-Ray diffraction (XRD) analysis supports the intercalation reaction of MACTS with MMT, since after intercalation reaction there is an increase in basal spacing. A scanning electron microscopy (SEM) image of drug loaded CH shows a smoother surface whereas blank CH has a cracked and rough surface, this reveals the high affinity of 5-FLU to CH. The encapsulation efficiency of CH reaches the maximum value of 94.0% with CH prepared using 4.0 g of MACTS/MMT, 1.5 g of AMPS, 0.75 g of MBA and 75.0% of drug loading. Swelling profiles obtained show that the CH swelling rate increases with increase of pH up to 6.4 and then starts to decrease. Release profiles of 5-FLU from CH have been studied under both simulated gastric and intestinal pH conditions. The results obtained show that the release rate of the loaded drug molecules was slow at pH 2.4 but increased significantly at pH 7.4. The cell viability test displayed that the 5-FLU loaded CH exhibited an enhanced cell inhibition than that of pure 5-FLU. The studies described in the paper demonstrate the potential viability of a pH-sensitive CH carrier for colon specific anticancer drugs.

Preparation and swelling properties of pH-sensitive composite hydrogel beads based on chitosan-g-poly (acrylic acid)/vermiculite and sodium alginate for diclofenac controlled release

A series of pH-sensitive composite hydrogel beads, chitosan-g-poly (acrylic acid)/vermiculite/sodium alginate (CTS-g-PAA/VMT/SA), was prepared using CTS-g-PAA/VMT composite and SA by Ca(2+) as the crosslinking agent. The structure and morphologies of the developed composite hydrogel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling properties and pH-sensitivity of the beads were investigated. In addition, the drug loading and controlled release behaviors of the beads were also evaluated using diclofenac sodium (DS) as the model drug in stimulated gastric fluids (pH 2.1) and intestinal fluids (pH 6.8). The results indicate that the composite hydrogel beads showed good pH-sensitivity. The release rate of the drug from the composite hydrogel beads is remarkably slowed down, which indicated that incorporating VMT into the composite hydrogel beads can improve the burst release effect of the drug.

Preparation and characterization of a novel pH-sensitive chitosan- g-poly (acrylic acid)/attapulgite/sodium alginate composite hydrogel bead for controlled release of diclofenac sodium

A series of pH-sensitive composite hydrogel beads composed of chitosan- g-poly (acrylic acid)/attapulgite/sodium alginate (CTS- g-PAA/APT/SA) was prepared as drug delivery matrices crosslinked by Ca 2+ owing to the ionic gelation of SA. The structure and surface morphology of the composite hydrogel beads were characterized by FTIR and SEM, respectively. pH-sensitivity of these composite hydrogels beads and the release behaviors of drug from them were investigated. The results showed that the composite hydrogel beads had good pH-sensitivity. The cumulative release ratios of diclofenac sodium (DS) from the composite hydrogel beads were 3.76% in pH 2.1 solution and 100% in pH 6.8 solutions within 24 h, respectively. However, the cumulative release ratio of DS in pH 7.4 solution reached 100% within 2 h. The DS cumulative release ratio reduced with increasing APT content from 0 to 50 wt%. The drug release was swelling-controlled at pH 6.8.