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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. [ABSTRACT FROM AUTHOR]

Polymers are a fundamental part of numerous industries and can be conjugated with many other materials and components to have a vast array of products. Biomaterials have been extensively studied for their application in pharmaceutical formulation development, tissue engineering, and biomedical areas. However, the native form of many polymers has limitations concerning microbial contamination, susceptibility, solubility, and stability. Chemical or physical modifications can overcome these limitations by tailoring the properties of polymers to meet several requirements. The polymer modifications are interdisciplinary, cutting across conventional materials, physics, biology, chemistry, medicine, and engineering limitations. Microwave irradiation has become a well-established technique for a few decades to drive and promote chemical modification reactions. This technique allows ease of temperature and power control to perform the synthesis protocols efficiently. Additionally, microwave irradiation contributes to green and sustainable chemistry. In this contribution, microwave-assisted polymer modifications were described with a special focus on their application in developing several novel dosage forms. [ABSTRACT FROM AUTHOR]

An organogel, a viscoelastic system, can be regarded as a semi-solid preparation which has an immobilized external apolar phase. The apolar phase is immobilized within spaces of the three-dimensional network structure formed due to the physical interactions amongst the self-assembling structures of compounds regarded as gelators. In general, organogels are thermodynamically stable in nature and have been explored as matrices for the delivery of bioactive agents. In the current paper, attempts have been made to understand the properties of organogels, various types of organogelators and some applications of the organogels in controlled delivery. [ABSTRACT FROM AUTHOR]

Due to their unique characteristics, dendrimers have attracted a great deal of attention over the past few years. The reason why they are of eminent interest in drug-delivery applications is that they have uniform size, water solubility, modifiable surface functionality and available internal cavities. Moreover, the high level of control over the dendritic architecture distinguishes them as ideal carriers. The bioactive agents may be encapsulated into the interior void spaces of the dendrimers or conjugated onto the dendrimer surface. Thus, they contribute to overcoming the challenge that quite a few drugs have low water solubility or cell membrane permeability and, therefore, never benefit patients. In this paper, we give a brief introduction of the synthesis of dendrimers, including divergent approach and convergent approach, and review two strategies used for drug-delivery applications and a vastly important function for gene transfection. [ABSTRACT FROM AUTHOR]

The principle aim of the present study is to synthesis a novel mesoporous silica-based dual drug delivery system (DDDS) with unique features for the delivery of amoxicillin (antibiotic) and thiamine hydrochloride (vitamin). The DDDS was characterized by Fourier transform infrared, X ray diffraction, differential scanning calorimetry, scanning electron microscopy and atomic force micrographs analyses. The stimuli response behaviour of the drug carrier was studied by conducting swelling experiments as a function of pH and time. Drug release studies were carried out by mimicking gastric and intestinal conditions and found that the release of both drugs attained its maximum in the intestinal condition. Thein vitrorelease data were analysed using Peppa’s potential equation in order to predict the release mechanism. The release of antibiotic follows non-Fickian mechanism whereas that of vitamin was diffusion controlled. Anin vitrocytotoxicity analysis was carried out on L929 cells and the results showed that the synthesized DDDS is safe. DPPH assay and antibacterial activity were also analysed. From the investigation, it is evident that the prepared DDDS has potential application as dual drug carrier. [ABSTRACT FROM PUBLISHER]

Polymer–metal complex nanoparticles-containing cisplatin (cis-dichlorodiammineplatinum(II)), an anticancer drug, was prepared by a ligand-exchange reaction of cisplatin with core-shell-type poly(citric acid)-b-poly(caprolactone)-b-poly(citric acid) (PCA–PCL–PCA). The resulting polymer–platinum complex nanoparticles showed a high loading capacity (up to 44.2% w/w). The TEM observation confirmed that the nanoparticles with spherical shape were formed by the mixing of PCA–PCL–PCA copolymer and cisplatin. According to TEM and DLS, polymer–cisplatin complex nanoparticles showed larger diameters compared with empty block copolymer attributed to some intermolecular crosslinkings through polymer–platinum (II) complex formation. The release profile of the platinum (II) complexes in phosphate-buffered saline medium at 37 °C indicated sustained manner of drug release.In vitrocytotoxicity evaluated by MTT assay, demonstrated that the PCA–PCL–PCA block copolymer does not exhibit apparent cytotoxicity. PCA–PCL–PCA–cisplatin complex nanoparticles showed greater cytotoxicity to HeLa cell line contrasted with free cisplatin, attributed to existence of poly (citric acid) moiety. [ABSTRACT FROM PUBLISHER]

In this work, magnetic sensitive hydrogel (ferrogel) was prepared by gamma irradiation of poly(ethylene glycol) (PEG)/ methacrylic acid (MAc) blends in the presence of Fe3O4particles. The release of vitamin B12 from ferrogels was studied in the absence of magnetic field (MFOFF) and under switching magnetic field (MFON). Different parameters such as effect of MAc ratio, temperature, pH and magnetic field on swelling and the release characters of vitamin B12 were investigated. The PEG/MAc ferrogels displayed magnetic sensitivity, in which the release of vitamin B12 increased greatly under switching magnetic field. The permeability coefficient (P) was calculated. The results suggested that this type of ferrogels may be considered as magnetic sensitive drug delivery systems. [ABSTRACT FROM PUBLISHER]

Polymeric forms of ionic liquids have many potential applications because of their ionic nature. Two ionic liquid monomers, 1-(4-vinylbenzyl)-3-methyl imidazolium hexafluorophosphate (VMIH) and 1-(4-vinylbenzyl)-4-(dimethylamino)-pyridinium hexafluorophosphate (VDPH), were synthesized through the quaternization of N-methylimidazole and 4-(dimethylamino) pyridine with 4-vinylbenzylchloride, respectively, and a subsequent anion exchange reaction with potassium hexafluorophosphate. The homopolymers of VMIH, VDPH, and its copolymers with methyl styrene (in various mole ratios) were synthesized by free radical polymerizations at 70 °C using α,α′-azobis(isobutyronitrile) as an initiator. Anionic drug molecule, naproxen (an anti-inflammatory drug), was effectively loaded into these positive charges polymers (PCP) and remained inside of the PCP under acidic environment (pH 2–6.5). The amount of loading of drug was increased with increasing positive charge densities resulting from the increasing number of ionic liquids groups. PCP as a controllable release of anionic drug molecules can be used as an oral delivery drug systems targeting at intestine. This drug can be remained trapped in the polymers when passing through the acidic and neutral environment and be released in intestine, where the environmental pH is close to basic. [ABSTRACT FROM PUBLISHER]

With cheap D,L-lactic acid (D,L-LA) and tryptophan (Try) as starting materials, a novel biodegradable material, poly(lactic acid-co-tryptophane) (P(LA-co-Try)), was synthesized via melt co-polycondensation. When the molar feed ratio LA/Try is 90:10, the influences of different conditions, including catalyst kinds and its dosage, co-polymerization time and temperature on the synthesis of the polymer are discussed. When SnCl2/ZnO (weight ratio 7:3) was used as catalyst at a dose of 0.7 wt% of the pre-polymer, 8 h direct-melt polycondensation at 160°C and absolute pressure of 70 Pa after pre-polymerization gave the co-polymer with a maximum intrinsic viscosity [η] of 0.73 dl/g. The structure of the co-polymer was characterized by FT-IR and 1H-NMR. According to the optimal synthetic conditions, co-polymers with different molar feed ratios were synthesized and systematically characterized by [η], FT-IR, 1H-NMR, GPC, DSC and XRD. The GPC results show that the maximum weight-average molecular weight (Mw) of P(LA-co-Try) is 6500 when the molar feed ratio LA/Try is 98:2. With the increase of the molar feed ratio of Try, [η], Mw and its polydispersity index (Mw/Mn) decrease gradually. Due to the introduction of Try with a big aromatic ring into the co-polymer, the glass-transition temperature (Tg) increases gradually with the increasing feed charge of Try and all co-polymers are amorphous. Direct-melt co-polycondensation is a cheap and practical method for the synthesis of Try-modified poly(lactic acid), a potential biomedical material, especially when used as a drug-delivery carrier. [ABSTRACT FROM AUTHOR]

Bioadhesion can be defined as the process by which a natural or a synthetic polymer can adhere to a biological substrate. When the biological substrate is a mucosal layer then the phenomena is known as mucoadhesion. The substrate possessing bioadhesive property can help in devising a delivery system capable of delivering a bioactive agent for a prolonged period of time at a specific delivery site. The current review provides a good insight on mucoadhesive polymers, the phenomenon of mucoadhesion and the factors which have the ability to affect the mucoadhesive properties of a polymer. [ABSTRACT FROM AUTHOR]

Synthetic polypeptides containing sugar moieties can find interesting applications as drug-delivery systems or as hydrogels. Only a few studies report on the successful synthesis of sugar-based polypeptides. The aim of this study is to access a range of well-defined polypeptides carrying linear gluconoyl moieties as side-groups, including homo-polypeptides and co-polypeptides with hydrophilic and hydrophobic sequences. The strategy consisted in first preparing the polypeptide via ring-opening polymerization of N-carboxyanhydrides using either an Al-Schiff's base metal complex or a primary amine. The free amino side-groups of the polylysine units are then reacted with gluconolactone, thus leading to a main polypeptide backbone and linear sugar moieties as pendant groups. Sugar moieties have also been attached to statistical and block co-polypeptides bearing hydrophilic and hydrophobic units such as L-lysine and L-leucine, respectively. The anchoring of linear gluconoyl moieties onto poly(L-lysine) and onto statistical and block co-polypeptides with lysine and leucine sequences is here reported for the first time. [ABSTRACT FROM AUTHOR]

pH-sensitive hydrogels are suitable candidates for oral delivery of therapeutic peptides, proteins and drugs, due to their ability to respond to environmental pH changes. Acetaminophen dimethylvinylsilyl ether was prepared under mild conditions. Cubane-1,4-dicarboxylic acid (CDA) linked to two HEMA groups, giving cubane-1,4-bis(methacryloyloxyethyl) carboxylate (CA), was used as cross-linker. The drug linked to dimethylvinylsilyl was abbreviated as ADVSi. Free radical cross-linking co-polymerization of polymerizable ADVSi with methacrylic acid (MAA) or N-vinyl-2-pyrrolidinone (NVP) with various ratios of CA as cross-linking agent was carried out with using AIBN as initiator in the temperature range 60–70°C. The structure of the ADVSi was confirmed by FT-IR and 1H-NMR spectroscopy. The composition of the cross-linked three-dimensional polymers was determined by FT-IR spectroscopy. The glass transition temperature (Tg) of the network polymers was determined calorimetrically. The hydrolysis of drug–polymer conjugates was carried out in cellophane membrane dialysis bags containing aqueous buffer solutions (pH 7.4 and pH 1) at 37°C. The effect of co-polymer composition on the hydrolytic degradation was studied in simulated gastric fluid (SGF, pH 1) and simulated intestinal fluid (SIF, pH 7.4) at 37°C. Detection of the hydrolysis product by UV spectroscopy shows that acetaminophen was released by hydrolysis of the ether bond located between the drug and the polymer chain. The drug-release profiles indicate that the amount of drug released depends on the composition of polymers. [ABSTRACT FROM AUTHOR]