Biodegradable polymeric micelles containing doxorubicin in the core region were prepared from a di-block copolymer composed of doxorubicin-conjugated poly(DL-lactic-co-glycolic acid) (PLGA) and polyethyleneglycol (PEG). The di-block copolymer of PLGA-PEG was first synthesized and the primary amino group of doxorubicin was then conjugated to the terminal hydroxyl group of PLGA, which ...

Paclitaxel is a widely used anti-cancer agent. Conjugates of paclitaxel with poly(glutamic acid) have shown great promise in preclinical trials, and clinical trials are now underway. Preclinical data suggest that more paclitaxel is preferentially delivered to tumor sites vs. nonconjugated paclitaxel. When poly(glutamic acid) is conjugated to other families of ...

Improved specificity and binding affinity by molecularly imprinted polymers is possible by development of novel functional materials. Furthermore, increasing the cross-link density of imprinted polymers by using cross-linking functional groups was anticipated to improve polymer molecular recognition. A novel cross-linking monomer derived from an L-aspartic acid precursor was synthesized and ...

A systemic study on the synthesis, characterization, degradation, drug release, and stability of nonlinear fatty acid terminated poly(sebacic anhydride) (PSA) is reported. Ricinoleic acid was transformed into a nonlinear fatty acid by esterification with fatty acid chlorides of C8-C18 chain length in the presence of pyridine. Pure nonlinear fatty acids ...

Poly(ethylene terephthalate) (PET) yarn with grafted poly(acrylic acid) (poly(AA)) was loaded with [6R-[6alpha,7beta(Z)]]-7-[[2-amino-4-thiazolyl)(methoxy-imino)acetyl]aminol-8-oxo-3-[[(1,2,5,6-tetrahydro-2-methyl-5,6-dioxo-1,2,4-triazin-3-yl)thio]-methyl]-5-thia-1-azabicyclo[4.2.0] oct-2-ene-2-carboxylic acid (Lendacin), a cephalosporin-type antibiotic. Immobilization of Lendacin was due to ionic interactions. Drug loading was varied from 0.61 to 5.29% wt/wt. The release of Lendacin from the modified PET fibers to water was monitored for ...

A telechelic poly(epsilon-caprolactone) having a degree of polymerization (DP) around 25 and two 4-aminobenzoyl chain ends was used as a macroinitiator for the ring-opening polymerization of various alpha-amino acid N-carboxyanhydrides (NCAs). Glycine-NCA, L-alanine-NCA, L-phenylalanine-NCA, and gamma-benzyl-L-glutamate-NCA served as monomers and the NCA/macroinitiator ratio was varied between 20:1, 40:1, and 100:1. ...

AIM: In a comparative in vitro study we examined the bactericidal effect, adhesion and shrinkage of 5% potassium nitrate in Carboxy-Adhaesor, 5% potassium chloride in Carboxy-Adhaesor, Carboxy-Adhaesor, Adhaesor and Dycal. MATERIAL AND METHODS: The bactericidal effect of the investigated pulp capping materials on the isolated microorganisms Staphylococcus aureus, Staph. epidermidis, ...

OBJECTIVES: Previous work has shown that steel attachments can be bonded to etched human enamel using anaerobic adhesives, following treatment with a solution of 0.05M copper (II) sulphate. The objectives of this experiment were to determine whether simultaneous etching and activation could be performed with a combined solution of o-phosphoric ...

STATEMENT OF PROBLEM: Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations. PURPOSE: This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners. ...

Poly-gamma-L-glutamic acid was synthesized in optimized fermentor cultivation of Bacillus licheniformis. The polypeptide obtained was esterified using benzyl- and butylbromides. Benzyl esters with 30, 60 and 100% degree of esterification were prepared. Solubility of the products in dimethyl sulfoxide, chloroform, methanol and in water was significantly different from these ones ...

The ability of osteoblasts to attach and function normally on scaffolds fabricated from synthetic materials is essential for musculoskeletal tissue engineering applications. In this study, the osteoconductivity of polymer networks formed from multifunctional lactic acid oligomers was assessed. These oligomers form highly crosslinked networks via a photoinitiated polymerization, which provides ...

This is the first report on the biosynthesis of a hitherto unknown, sulfur-containing polyester and also the first report on a bacterial polymer containing sulfur in the backbone. The Gram-negative polyhydroxyalkanoate (PHA)-accumulating bacterium Ralstonia eutropha synthesized a copolymer of 3-hydroxybutyrate and 3-mercaptopropionate, poly(3HB-co-3MP), when 3-mercaptopropionic acid or 3,3'-thiodipropionic acid was ...

The effect of terminal sterilization by gamma-irradiation on several ricinoleic acid based polyanhydrides was investigated. The following polymers were used: poly(ricinoleic acid maleate) [P(RAM)], poly(ricinoleic acid succinate) [P(RAS)], poly(hydroxy stearic acid succinate) [P(HSAS)], poly(hydroxy stearic acid maleate) [P(HSAM)], and their copolymers with sebacic acid. The polymers were irradiated with an ...

A general method for the synthesis of (14)C-acrylic acid is described in detail. The material is used for the synthesis of a range of radiolabeled poly(acrylic acid)s in which the (14)C-label forms an integral part of the polymer backbone. The chemical structure of the synthesized polymers is examined in the ...

Epidemiological studies have shown that the prevalence of dental erosion in children varies widely between 2 and 57%. Changes seen in dental erosion range from removal of surface characteristics to extensive loss of tooth tissue with pulp exposure and abscess formation. Symptoms of dental erosion range from sensitivity to severe ...

Hydrophobically modified polyelectrolytes (HMP) are polymers with a high content of ionizable groups bonded to hydrophobic groups. Copolymers of poly(acrylic acid) and Pluronic surfactants constitute a special class of HMP whereby poly(propylene oxide) segments act as hydrophobes. The poly(propylene oxide) segments possess temperature-dependent aqueous solubility and the solutions of the ...

A series of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)s [P(3HB-co-4HB)s] with different 4HB content, biosynthesized by Ralstonia eutropha H16 with mixed carbon sources of 4-hydroxybutyric acid (4HBA) and butyric acid, were fractionated by solvent/nonsolvent fractionation into copolyester fractions with different 4HB content and narrower compositional distribution. The fractions obtained were classified into two groups, 3HB- ...

New poly(beta-hydroxyalkanoates) having aromatics groups (so-called PHPhAs) from a microbial origin have been characterized. These polymers were produced and accumulated as reserve materials when a beta-oxidation mutant of Pseudomonas putida U, disrupted in the gene that encodes the 3-ketoacyl-CoA thiolase (fadA), was cultured in a chemically defined medium containing different ...

Stearic acid esters of poly(ethylene oxide)-block-poly(hydroxyethyl L-aspartamide) and poly(ethylene oxide)-block-poly(hydroxyhexyl L-aspartamide) have been synthesized from poly(ethylene oxide)-block-poly(beta-benzyl L-aspartate) by polymer-analogous reactions and self-assembled into a micelle. Transmission electron microscopy and fluorescent probe studies reveal that the micelle mimics structural features of serum lipoproteins: it is nanoscopic, spherical, and has a ...

An amphiphilic coating is configured as a substantive film that has a tendency for an in-plane two-dimensional polymerization. This coating is hypothesized to protect enamel from in vitro acid decalcification, assessed through the following artificial caries model. Three regions on labial enamel of eight bovine incisors were treated with an ...

Ultrathin sectioning and cryofracture of fibrous kerite, sampled from 1.8-1.75 billion year old Volyn sediments (Ukraine), revealed in bacteria-like bodies the presence of structures similar to sheath, cell wall, periplasm, cytoplasm, septum, membranes, intramembrane particles, poly-beta-hydroxybutyrate inclusions. On the strength of these data and also the fatty acid profiles of ...

Lipase catalysis in nonaqueous media is recognized as a powerful tool in organic and more recently polymer synthesis. Even though none of the currently known polyhydroxyalkanoate (PHA) depolymerases have lipase activity, they do have a catalytic center that resembles that of lipases. Motivated by the above, the potential of using ...

The main purpose of this work is to formulate benzathine penicillin G nanoemulsion and nanocapsules, to evaluate their physicochemical and stabilising characteristics, and to determine their antimicrobial activity and penicillin in vitro release kinetics. Nanoemulsions were produced by the spontaneous emulsification approach and nanocapsules of poly (D,L-lactic acid-co-glycolic acid) polymer ...

The construction of a l-lysine biosensor on a Si-gold strip electrode (SGSE) is described in this study. The construction comprises (a) the formation of poly(o-phenylenediamine, o-PD) membrane on the electrode surface via electropolymerization and (b) the immobilization of lysine oxidase on the gold/poly(o-PD) electrode with glutaraldehyde. The behavior of the ...

Rifampicin polylactic acid microspheres for lung targeting were prepared by a modified emulsion-solvent diffusion method. The microspheres were free flowing, spherical with regular surface. Drug content, particle size distribution and in vitro release properties of the prepared microspheres were evaluated. In vivo experiments on rabbits showed remarkable accumulation of microspheres ...

A biodegradable poly(anhydride-ester) was synthesized by melt condensation polymerization of the acetylated monomer to yield a novel polymeric prodrug. The polymer we have synthesized is composed of alkyl chains linked by ester bonds to aromatic moieties, specifically salicylic acid--the active component of aspirin. With the medicinal properties attributed to salicylic ...

Sales of soft drinks has been increasing by 56% over the last 10 years and are estimated to keep rising at about 2-3% a year. Further, the reported incidence of tooth erosion has been increasingly documented. Whilst these factors could well be linked, many individuals with erosive diets are not ...

The isolation of a ribonuclease designated lactoribonuclease, with a molecular weight and an N-terminal amino acid sequence identical to those of bovine pancreatic ribonuclease, was first reported from bovine milk. After removal of globulin from acid whey by precipitation with 1.8 M (NH4)2SO4, (NH4)2SO4 was added to attain a concentration ...

A natural polysaccharide, chitosan (poly-N-acetyl glucosaminoglycan), which is a nontoxic and bioabsorbable polymer, has been shown to have hemostatic and antibacterial effects. An amino acid, taurine, is considered to be beneficial for regulating the inflammation process. The purpose of this study was to investigate the synergistic effects of taurine and ...

The purpose of this study was to determine the effects of changing the type of enamel conditioner on the shear bond strength of a resin-reinforced glass ionomer within half an hour after bonding the bracket to the tooth. Freshly extracted human molars were collected and stored in a solution of ...

The surface of ultrahigh molecular weight polyethylene (UHMWPE) was modified by radiation-grafting methylmethacrylate (MMA) in the presence of sulfuric acid and metallic salt to increase bonding strength with polymethylmethacrylate. The effect of the addition of metallic salts and sulfuric acid on the radiation grafting reaction was investigated when MMA was ...

Periodontal wafers intended to treat the underlying infections in patients with periodontitis have been developed. The wafers consist of poly(lactic-co-glycolic acid) as a primary bioerodible polymeric component, poly(ethylene glycol) as a plasticizer and encapsulation aid, and silver nitrate as the antimicrobial agent. The wafers are capable of sustained in vitro ...

The polyaniline (PANI) dispersions have been prepared in acidic aqueous media by oxidative dispersion polymerization in the presence of a polymeric stabilizer. The polymeric stabilizer used in this study is the poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) which contains acid groups (-COOH). The PANI-PMVEMA particles have a uniform size and a ...

Methacrylic acid (MAA) and 2-(trifluoromethyl)acrylic acid (TFMAA) were used to prepare molecularly imprinted polymers exhibiting diastereoselectivity for cinchona alkaloids. Fluorescent spectra of the cinchona alkaloid exhibit a characteristic shift through binding to these polymer particles, originating most likely from the highly acidic residues in the imprinted polymers acting as a ...

An efficient method for the preparation of optically active alkyl (R)-(-)-3-hydroxybutyrates by chemical depolymerization of biopolymer, poly-(R)-(-)-(3-hydroxybutyrate), was established. This method consists of simple recovery of poly-(R)-(-)-(3-hydroxybutyrate) from bacterial cells followed by acidic alcoholysis. When poly-(R)-(-)-(3-hydroxybutyrate) was purified by a simple digestion method that used 0.2 N sodium hydroxide, alkyl ...

To improve the properties of a reversible synthetic extracellular matrix based on a thermally reversible polymer, copolymers of N-isopropylacrylamide and acrylic acid were prepared in benzene with varying contents of acrylic acid (0 to 3%) and the thermal properties were evaluated. The poly(N-isopropylacrylamide) and copolymers made with acrylic acid had ...

Poly(N-acryl amino acids) bearing side groups with a lipophilic character or having charged functional groups (i.e. -NH(2), -COOH, -SH, -OH, and phenols) were synthesized from the radical polymerization of N-acryl amino acid monomers. Monomers were prepared from the reaction of acryloyl chloride and amino acid esters in dry solvents. Polymers ...

The purpose of this study was to design poly(lactide-co-glycolide) (PLGA) microspheres for the continuous delivery of the somatostatin analogue, vapreotide, over 2-4 weeks. The microspheres were produced by spray-drying and the desired characteristics, i.e. high encapsulation efficiency and controlled release over 2-4 weeks, achieved through optimizing the type of polymer, ...

Based on the H2O-P2O5-CaO phase diagram, we hypothesize that a phosphoric acid concentration around 27 wt% leaches most calcium from dentin. We also hypothesize that bond strength is affected by resin infiltration, and that resin infiltration becomes incomplete when calcium leakage exceeds a certain value. Dentin disks were cut from ...

STATEMENT OF PROBLEM: Fracture of porcelain is a relatively common clinical misfortune. Recent research has indicated that strong bonds can be formed between composite and dental porcelain. Porcelain surfaces are etched with hydrofluoric acid and treated with silane coupling agents before composite application. The question is how exposed dentin may ...

A new biodegradable delivery system based on poly(lactic acid) has been formulated, with potential applications in sustained antibiotic release against bone infection. The in vitro release of a new quinolone (pefloxacin) from low molecular weight poly(D,L-lactic acid) Mw = 2 x 10(3) lasted for 56 d whereas the in vivo ...

The design and development of novel pH-sensitive liposomes were investigated to improve the release of liposome-encapsulated chemicals. Stable liposomes comprising of L-alpha-dipalmitoylphosphatidylcholine (DPPC) and poly(carboxylic acid) were prepared and characterized. Poly(malic acid) (PMLA) was chosen as a fusogen, because of its excellent biodegradability in physiological regions. Octyl groups introduced in ...

Based on the relationship between in vivo disposition of macromolecules and their physicochemical and biological characteristics obtained through clearance concept-based pharmacokinetic analysis, polymeric prodrugs of prostaglandin E1 (PGE1) were designed stepwise and evaluated on their targeting and therapeutic efficiencies. Although galactosylated poly-L-glutamic acid with a ethylene diamine (ED) spacer (Gal-ED-PLGA) ...

The application of the hydrophilic methacrylate primer to acid-etched dentin increases the bond strength of the resin to the acid-etched dentin. However, the mechanism for the bonding of the resin to dentinal collagen through the primer remains to be determined. Before a more effective adhesive primer can be developed, we ...

Glycolic acid is used in many cosmetic products as exfoliant and moisturizer. Unfortunately, the greater glycolic acid cosmetic benefits the greater is the potential for skin irritation as far as burning. The aim of this work was to investigate the feasibility of topical controlled delivery systems loading glycolic acid in ...

A new pathway to synthesize poly(hydroxyalkanoic acids) (PHA) was constructed by simultaneously expressing butyrate kinase (Buk) and phosphotransbutyrylase (Ptb) genes of Clostridium acetobutylicum and the two PHA synthase genes (phaE and phaC) of Thiocapsa pfennigii in Escherichia coli. The four genes were cloned into the BamHI and EcoRI sites of ...

The purpose of this study was to evaluate the effects of 2 new acid-etching solutions, nonrinse conditioner (NRC) and 17% ethylenediaminetetraacetic acid (EDTA), on enamel surface morphology, and to compare the new solutions with traditional 37% phosphoric acid. The effect of prolonged etching time was also investigated. The buccal surfaces ...

The purpose of this paper was to study the effect of the isopropyl myristic acid ester (IPM) on the physicochemical characteristics of etoposide-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres-specifically, the effects on the size and drug loading of the microspheres, the polymer matrix and surface morphology, and the release of etoposide from ...

PURPOSE: The purpose of this study was to determine the relative contributions of the mineral and organic phases of dentin to its total buffering capacity and to compare the buffering abilities of normal and caries-affected dentin for acids used in adhesive dentistry. MATERIALS AND METHODS: Disks of normal and caries-affected ...

The purpose of this study was to compare the conventional acid-etch technique with an air abrasion surface preparation technique. Eighty freshly extracted noncarious human premolar teeth were randomly divided into the following 4 groups: (1) acid etched with 37% phosphoric acid for 15 seconds (Express Dental Products, Toronto, Canada), (2) ...