The effect of solvent composition on vancomycin hydrochloride and free base vancomycin release from in situ forming implants

In situ forming drug delivery systems that are formed by solvent‐induced phase inversion have attracted extensive attention in sustained delivery of peptides and proteins. Based on the findings of our previous studies, N‐methyl‐2‐pyrrolidone (NMP) and acetone are two solvents that could improve the release profile of vancomycin from in situ forming systems based on poly(D,L‐lactide‐co‐glycolic acid). In this study, the effect of different compositions of these solvents on the release profile of hydrochloride and free base forms of vancomycin was investigated. To this end, several formulations with vancomycin (either hydrochloride or free base form) and different proportions of NMP and acetone were prepared. The cumulative drug release at specified time was determined and tested against conventional kinetic models. The surface and cross‐sectional morphology of implants were investigated by SEM. The experimental results showed that as solvent composition changed, the amount of vancomycin release during the first 12 h changed, too. The use of free base vancomycin resulted in an extended vancomycin release profile with less initial burst release. The formulation containing free base vancomycin and mixed solvents of acetone and NMP in 2:1 ratio released 70% of loaded drug in 6 weeks with near zero‐order kinetic. The best kinetic model to fit the in vitro release profiles was found to be Peppas–Sahlin model. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of Sodium Alginate on the Properties of Thermosensitive Hydrogels

Sodium alginate (SA ) was combined with poly(N ‐isopropylacrylamide) (PNIPAAm ) to prepare thermosensitive hydrogels through semi‐interpenetrating polymer network (semi‐IPN ) and fully interpenetrating polymer network (full‐IPN ). The thermosensitive, swelling, mechanical, and thermal properties of pure PNIPAAm , SA /PNIPAAm semi‐IPN , and Ca‐alginate/PNIPAAm full‐IPN hydrogels were investigated. The formation of semi‐IPN and full‐IPN significantly improved the hydrogels’ swelling capability and mechanical properties without altering their thermosensitivity. 5‐Fluorouracil (5‐Fu) was selected as a model drug to study the release behaviors of the hydrogels. It was found that in vitro controlled drug release from semi‐IPN hydrogels showed an initial release burst, followed by a slower and sustained release, before reaching equilibrium. Full‐IPN hydrogels showed slow and sustained release during the whole process. Temperature and pH were found to affect the rate of drug release. Ca‐alginate/PNIPAAm full‐IPN hydrogels have potential application as drug delivery matrices in controlled drug release.     

Light and pH Dual‐Degradable Triblock Copolymer Micelles for Controlled Intracellular Drug Release

A novel amphiphilic ABA‐type triblock copolymer poly(ethylene glycol)‐b‐poly(ethanedithiol‐alt‐nitrobenzyl)‐b‐poly(ethylene glycol) (PEG‐b‐PEDNB‐b‐PEG) is successfully prepared by sequential thiol‐acrylate Michael addition polymerization in one pot. PEG‐b‐PEDNB‐b‐PEG is designed to have light‐cleavable o‐nitrobenzyl linkages and acid‐labile β‐thiopropionate linkages positioned repeatedly in the main chain of the hydrophobic block. The light and pH dual degradation of PEG‐b‐PEDNB‐b‐PEG is traced by gel permeation chromatography (GPC). Such triblock copolymer can self‐assemble into micelles, which can be used to encapsulate anticancer drug doxorubicin (DOX). Because of the different degradation chemistry of o‐nitrobenzyl linkages and β‐thiopropionate linkages, DOX can be released from the micelles by two different manners, i.e., light‐induced rapid burst release and pH‐induced slow sustained release. Confocal laser scanning microscopy (CLSM) results indicated that DOX‐loaded micelles exhibited faster drug release in A549 cells after UV irradiation. Furthermore, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) results show that the DOX‐loaded micelles under UV light degradation exhibit better anticancer activity against A549 cells than that of the nonirradiated ones.

     

Relationship among drug delivery behavior,degradation behavior and morphology of copolylactones derived from glycolide,l‐lactide and ε‐caprolactone

A series of copolylactones was synthesized by ring‐opening copolymerization of glycolide, L ‐lactide and ?‐caprolactone, using stannous octoate as catalyst. The in vitro degradation behaviors of them were studied and data demonstrated different degradation rates which mainly depended on the compositions. Investigation of the 5‐fluorouracil (5‐Fu) release from these copolylactones revealed that the composition, degradation rate and the morphology of the polymeric matrix played an important role on the drug release kinetics. A sustained 5‐Fu release without initial time lag was obtained from random poly(lactide‐co‐glycolide‐co‐caprolactone) (r‐PGLC) drug carrier, and it differed from the cases of polylactide (PLA) or random poly(lactide‐co‐glycolide) (PLGA), which usually showed an initial time lag or biphasic drug release behavior. It was due to the low glass transition temperature (T _g) of the r‐PGLC and the drug would diffuse faster in rubbery state under the experimental temperature. Furthermore, a significant change in the drug release behavior of r‐PGLC was observed when the temperatures were changed around the T _g of the drug carrier, which implied that the drug release behavior could be regulated by adjusting the morphology of the drug carrier. Copyright © 2002 John Wiley & Sons, Ltd.     

Achieving High Drug Loading and Sustained Release of Hydrophobic Drugs in Hydrogels through In Situ Crystallization

Inadequate drug loading of hydrophobic drugs is a classic problem when hydrogels are utilized as sustained‐release carriers of drugs. Herein, a strategy to load plenty of hydrophobic drugs is presented. The antitumor drug 10‐hydroxycamptothecin in the thermogel of poly(d ,l ‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly(d ,l ‐lactic acid‐co‐glycolic acid) is employed. The drug is soluble in an alkaline medium, yet insoluble in a neutral/acidic medium. The crystallization is triggered after adding an alkaline drug solution into an acidic copolymer solution. The concentrated copolymer aqueous solution undergoes a sol–gel transition upon heating, faster than the crystallization. As a result, plenty of evenly dispersed drug microcrystals are formed. The in vitro and in vivo experiments indicate both high drug loading and sustained release with enhanced antitumor efficacy and reduced adverse effects. The system resolves the challenge in formulation of hydrophobic drugs in hydrogels, and is stimulating for encapsulating drugs with a soluble‐insoluble transition into a material environment.

     

pH and reduction dual‐stimuli‐responsive PEGDA/PAMAM injectable network hydrogels via aza‐michael addition for anticancer drug delivery

A pH and reduction dual‐stimuli‐responsive PEGDA/PAMAM injectable network hydrogel containing “acetals” as pH‐sensitive groups and “disulfides” as reducible linkages was designed and synthesized via aza‐Michael addition reaction between PAMAM and PEGDA diacrylates. The pore size and swelling ratio of hydrogels was varied from 14 ± 3 to 19 ± 4 μm and 214 ± 13 to 300 ± 19 μm, respectively, with varying ethylene glycol repeating units in diacrylates. The swelling ratio of PEGDA/PAMAM network hydrogel increased with increase in the molecular weight of PEG and with decrease in pH. The presence of different cationizable amino‐functionalities in PEGDA/PAMAM network hydrogel helped to enhance the swelling ability of hydrogel under the acidic conditions. The continuous increase in metabolically active live HeLa cells with time in MTT assay implied biocompatibility/noncytotoxicity of the synthesized PEGDA/PAMAM injectable network hydrogel. Furthermore, the prepared PEGDA/PAMAM hydrogel showed higher degradation at lower pH and at higher concentration of DTT. The burst release of doxorubicin from PEGDA/PAMAM hydrogel under the environment of the lower pH and in presence of DTT compared to the release at normal physiological pH and in absence of DTT suggested the potential ability of this model hydrogel system for targeted and selective anticancer drug release at tumor tissues. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2080–2095     

Hydrogen‐Bonded Films for Zero‐Order Release of Leuprolide

Leuprolide has been widely used in androgen deprivation therapy for the treatment of advanced prostate cancer, but its use is still limited due to its short half‐life. Herein, hydrogen‐bonded layer‐by‐layer films are fabricated from PEGylated leuprolide (PEG‐LEU) and tannic acid (TA). Because of its dynamic nature, the film disintegrates gradually in water and releases PEG‐LEU and TA. The in vitro release profile indicated perfect zero‐order kinetics, which is explained by the unique release mechanism. When implanted subcutaneously in male rats, the films maintain a constant serum drug level. For a 60‐bilayer film, the serum drug level is maintained constant for ≈24 days. No initial burst release is observed, suggesting that the in vivo release also follows zero‐order kinetics. Initially, an increase in the level of serum testosterone is induced by the released drug, followed by testosterone suppression to a constant level below the castrate level, which could be maintained as long as a constant serum drug level is maintained. Since the new drug carriers avoid an initial burst release of the drug and maintain a constant serum drug level and hence a constant serum testosterone level below the castrate level, these carriers are highly promising for androgen deprivation therapy.     

Photoacoustic Imaging Quantifies Drug Release from Nanocarriers via Redox Chemistry of Dye‐Labeled Cargo

We report a new approach to monitor drug release from nanocarriers via a paclitaxel–methylene blue conjugate (PTX‐MB) with redox activity. This construct is in a photoacoustically silent reduced state inside poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles (PTX‐MB@PLGA NPs). During release, PTX‐MB is spontaneously oxidized to produce a concentration‐dependent photoacoustic signal. An in vitro drug‐release study showed an initial burst release (25 %) between 0–24 h and a sustained release between 24–120 h with a cumulative release of 40.6 % and a 670‐fold increase in photoacoustic signal. An in vivo murine drug release showed a photoacoustic signal enhancement of up to 649 % after 10 hours. PTX‐MB@PLGA NPs showed an IC₅₀ of 78 μg mL^?1 and 44.7±4.8 % decrease of tumor burden in an orthotopic model of colon cancer via luciferase‐positive CT26 cells.     

Enhanced gentamicin loading and release of PLGA and PLHMGA microspheres by varying the formulation parameters

The purpose of this study was to develop a suitable formulation for gentamicin sulfate (GS) that gives a sustained release of the drug. Therefore this drug was loaded into poly(D,L-lactide-co-glycolide) (PLGA) and poly(lactic-co-hydroxymethyl glycolic acid) (PLHMGA) microspheres. The effects of various formulation parameters (ethanol, surfactant, osmotic value of the external phase, polymer type and concentration) on particle characteristics (size, loading and release) were investigated. The GS loaded microspheres were prepared using a double emulsion evaporation technique. The results demonstrate that neither ethanol nor surfactants had beneficial effects on the drug loading efficiency (around 4-10%). However, an increase in buffer concentration (and thus osmotic pressure) of the external phase resulted in a substantial increase of GS-loading (from 10 to 28%). Further, an increase of concentration of PLGA in DCM from 10% to 15/20% caused a 4-time increase of the drug loading. The best formulation identified in this study had a loading efficiency of around 70% resulting in PLGA microspheres with a 6% (w/w) loading. The particles showed a burst release of the drug depending on their porosity, followed by a phase of 35 days where hardly any release occurred. The drug was then slowly released for around 25 days likely due to degradation of the microspheres. The drug loading efficiency of GS in PLHMGA was not significantly different from PLGA microspheres (64%). The release of GS from PLHMGA microspheres was faster than that of PLGA because the degradation rate of PLHMGA is more rapid than PLGA. This study shows that prolonged release of gentamicin can be obtained by loading this drug into microspheres made of biodegradable aliphatic polyesters.     

The effect of additives on naltrexone hydrochloride release and solvent removal rate from an injectable in situ forming PLGA implant

Biodegradable in situ forming drug delivery systems for naltrexone release are promising for post‐treatment of drug addicts. The effect of two different additives, glycerol and ethyl heptanoate, on the naltrexone hydrochloride release and solvent removal from a poly(DL ‐lactide‐co‐glycolide) (PLGA) injectable implant is presented in this article. The experimental results showed that the in vitro initial release of the drug was decreased in the presence of these additives. Ethyl heptanoate was, however, more effective than glycerol and increasing the amount of additives in PLGA solution up to 5% (w/w) resulted in a decrease of initial naltrexone release rate up to 50%. The morphological evaluation of implants using scanning electron microscopy indicated that the additives generated a less porous structure together with a finger‐like to sponge‐like transition. The solvent removal profiles of injectable implants, which can be well described by thermogravimetric and morphological analysis, were in good agreement with drug release profiles. Copyright © 2006 John Wiley & Sons, Ltd.     

Complex micelles formed from two diblock copolymers for applications in controlled drug release

Double‐responsive core‐shell‐corona complex micelles for applications in drug release were formed from self‐assembly of two diblock copolymers PtBA‐b‐ PNIPAM and PtBA‐b‐P4VP. The two diblock copolymers coaggregated into core‐shell complex micelles in acidic water with the hydrophobic PtBA blocks as the common core and soluble PNIPAM/P4VP blocks as the mixed shell. Increasing temperature or pH value, the micelles converted into core‐shell‐corona micelles because of the collapse of PNIPAM or P4VP blocks as the inner shell and soluble P4VP or PNIPAM chains stretching outside as the outer corona. The anti‐inflammation drug naproxen (NAP) was loaded as the model drug in micelles in acidic water and released because of the ionization of NAP in alkaline solutions. Compared with pure core‐shell micelles, release of NAP from core‐shell‐corona complex micelles avoided the burst diffusion and the release rate is more easily controlled by tuning the composition of the mixtures or by adjusting the pH of the medium. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1804–1810, 2009     

Phospholipid coated poly(lactic acid) microspheres for the delivery of LHRH analogues

The aim of this work was to develop alternative peptide‐loaded microspheres using liposphere formulation—a lipid based microdispersion system. This formulation represents a new type of lipid or polymer‐based encapsulation system developed for parenteral and topical drug delivery of bioactive compounds. Our strategy was to utilize the liposphere formulation to improve the entrapment efficiency and release profile of triptorelin and leuprolide [luteinizing hormone–releasing hormone (LHRH) analogues] in vitro. Peptides (2% w/w) were loaded into lipospheres contained of polylactic acid (PLA) or poly(lactic‐co‐glycolic acid) (PLGA) with several types of phospholipids. The effects of polymer and phospholipid type and concentration, method of preparation and solvents on the liposphere characteristics, particle size, surface and bulk structure, drug diffusion rate, and erosion rate of the polymeric matrix were studied. The use of L ‐PLA (M_w = 2000) and hydrogenated soybean phosphatidylcholine (HSPC) with phospholipid–polymer ratio of 1 : 6 w/w, was the most efficient composition that formed lipospheres of particle size in the range of 10 µm with most of the phospholipid embedded on the particles surface. In a typical procedure, peptides were dissolved in N‐methyl‐2‐pyrrolidone (NMP), and dispersed in a solution of polymer and phospholipids in a mixture of NMP and chloroform with the use of 0.1% poly(vinyl alcohol) (PVA) as the emulsified aqueous medium. Uniform microspheres were prepared after solution was mixed at 2000 rpm at room temperature for 30 min. Using this formulation, the entrapment efficiency of LHRH analogues in lipospheres was up to 80%, and the peptides were released for more than 30 days. Copyright © 2002 John Wiley & Sons, Ltd.     

In situ gel forming graft copolymers of a polyaspartamide and polylactic acid: Preparation and characterization

In situ gel forming systems have been prepared by linking polylactic acid (PLA) to a water soluble and polyfunctional polymer, such as α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA). Three graft copolymers PHEA-PLA with a different derivatization degree in PLA, have been synthesized and characterized. PHEA-PLA graft copolymer with the highest amount in PLA has been used to prepare solutions in organic solvents able to give rise to gel-like matrices when injected into phosphate buffered saline solution. The chemical degradation of these gels has been evaluated and in vitro tests have been performed to evaluate the cell compatibility of the hydrolysis products. The possibility to use these gels for drug release has been investigated by incorporating leuprolide as a peptide model drug and by evaluating its in vitro release. To improve the drug release profile, PHEA-PLA graft copolymer has been derivatized with pendant carboxylic groups that are able to form an ion pair with the leuprolide thus reducing the burst effect and prolonging its release.     

Development and validation of HPLC method for simultaneous estimation of piperine and guggulsterones in compound Unani formulation (tablets) and a nanoreservoir system

An attempt has been made to develop and validate a simultaneous HPLC method for novel approach of drug release via oil‐in‐water (o/w) nanoemulsion formulation and Habb‐e‐Khardal Unani tablet containing piperine and guggul sterones E and Z as main ingredients. Nanoemulsion was prepared by titration method using sefsol‐218 as an oily phase, cremophor‐EL as a surfactant, transcutol as a co‐surfactant and distilled water as an aqueous phase. The formulation was optimized on the basis of thermodynamic stability and dispersibilty test. The nanoformulation was evaluated for particle size, surface morphology, electrical conductivity and viscosity determination. The in vitro dissolution was carried out by dialysis bag method. Drugs were quantified using an HPLC method developed in‐house with a C₁₈ column as stationary phase and acetonitrile and water as mobile phase at λ_max of 240 nm. The optimized formulation showed higher drug release, lower droplet size and less viscosity as compared with the conventional Habb‐e‐Khardal Unani tablet. The present study illustrated the potential of nanoemulsion dosage form in improving biopharmaceutic performance of piperine and guggul sterone. The HPLC method was also found to be quite sufficient for the routine quality control of formulations containing piperine and guggul sterone E and Z as ingredients and also for in vitro drug release studies. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of molecular weight and degree of deacetylation on controlled release of isoniazid from chitosan microspheres

Glutaraldehyde cross‐linked chitosan microspheres for controlled release of isoniazid were prepared using chitosan of different molecular weights (MWs) and degrees of deacetylation (DDAs). Chitosan microspheres were characterized for their size, hydrophobocity, degree of swelling and loading of isoniazid. Hydrophobicity of chitosan microspheres increased on increasing the degree of cross‐linking and MW of chitosan. Chitosan microspheres with high degree of deacetylation (DDA) (75 wt%), high MW chitosan (2227 kg mol^?1), and with 12 wt% concentration of glutaraldehyde showed optimum loading and release of isoniazid. The isoniazid from chitosan microspheres was released in two steps, i.e. burst (%R_B) and controlled (%R_C) steps. The microspheres with low MW chitosan (260 kg mol^?1) and low DDA (48 wt%) showed prominent burst release of isoniazid, but microspheres with high MW chitosan (2227 kg mol^?1) and high DDA (75 wt%) have released more isoniazid in a controlled manner (60 wt%) at 37°C in a solution of pH 5.0 ± 0.1. The burst step of drug release (%R_B) has followed first order kinetics, whereas controlled step of drug release (%R_C) followed zero order kinetics. The burst step of drug release was Fickian and controlled step was non‐Fickian in nature. The diffusion constant (D) for isoniazid release was influenced by the properties of chitosan and degree of cross‐linking. Copyright © 2007 John Wiley & Sons, Ltd.     

Investigation of drug release and 1H‐NMR analysis of the in situ forming systems based on poly(lactide‐co‐glycolide)

In situ forming biodegradable polymeric systems loaded with betamethasone (BTM) and betamethasone acetate (BTMA) were prepared using poly(DL ‐lactide‐co‐glycolide) (PLGA), ethyl heptanoate (EH), and N‐methyl‐2‐pyrrolidone (NMP) as the biodegradable polymer, additive, and solvent, respectively. The drug release studies were carried out in buffer (pH = 7.4, 37°C) using high performance liquid chromatography (HPLC). ¹H‐NMR was used to determine the polymer degradation behavior, release mechanism, and interactions between the polymer and drug. The ¹H‐NMR spectra showed that all interactions between the polymer and drug were hydrogen bonding. Hydroxyl groups and fluorine in drugs were involved in hydrogen bonding with PLGA polymer. In ¹H‐NMR studies, we found that the degradation rate in the systems loaded with BTMA was higher than the systems loaded with BTM because BTMA is only slightly soluble and accelerates the hydrolysis of PLGA chains. The formulations loaded with BTM had obviously lower burst release compared with BTMA loaded samples. With respect to ¹H‐NMR spectra, the mechanism of BTM release is controlled by two effective factors: solvent removal and polymer degradation. Copyright © 2008 John Wiley & Sons, Ltd.     

Comparative isoconversional thermal analysis of Artemisia vulgaris hydrogel and its acetates; a potential matrix for sustained drug delivery

Abstract

Artemisia vulgaris hydrogel (AVH) was acetylated (AAVH) and characterized by FTIR, CP/MAS ¹³C-NMR spectroscopic techniques and thermogravimetric analysis. Flynn–Waal–Ozawa model was used to investigate thermal degradation kinetics. Energy of activation (Ea) values of first and major thermal degradation steps were found to be 128.14 and 116.85 kJmol^?1 for AVH and AAVH, respectively. Thermodynamic triplet, order of degradation reaction, integral procedural decomposition temperature (IPDT) and comprehensive index of intrinsic thermal stability (ITS) were also taken into account. In vitro caffeine release from AVH-based matrix tablets indicates potential of AVH for the development of oral delivery systems for sustained drug release.     

Dual crosslinked pH‐ and temperature‐sensitive hydrogel beads for intestine‐targeted controlled release

Novel drug‐loaded hydrogel beads for intestine‐targeted controlled release were developed by using pH‐ and temperature‐sensitive carboxymethyl chitosan‐graft‐poly(N,N‐diethylacrylamide) (CMCTS‐g‐PDEA) hydrogel as carriers and vitamin B₂ (VB₂) as a model drug. The hydrogel beads were prepared based on Ca²⁺ ionic crosslinking in acidic solution and formed dual crosslinked network structure. The structure of hydrogel and morphology of drug‐loaded beads were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The study about swelling characteristics of hydrogel beads indicated that the beads had obvious pH‐ and temperature‐sensitivity. In vitro release studies of drug‐loaded beads were carried out in pH 1.2 HCl buffer solution and pH 7.4 phosphate buffer solution at 37°C, respectively. The results indicated that the dual crosslinked method could effectively control the drug release rate under gastrointestinal tract (GIT) conditions, which was superior to traditional single crosslinked beads. In addition, the effects of grafting percentage, pH value, and temperature on the release behavior of the VB₂ were investigated. The drug release mechanism of CMCTS‐g‐PDEA drug‐loaded beads was analyzed by Peppa's potential equation. According to this study, the dual crosslinked hydrogel beads based on CMCTS‐g‐PDEA could serve as suitable candidate for drug site‐specific carrier in intestine. Copyright © 2009 John Wiley & Sons, Ltd.     

In vitro evaluation of sustained release of risperidone‐loaded microspheres fabricated from different viscosity of PLGA polymers

The aim of this study was to fabricate different risperidone (RIS)–loaded poly(lactic‐co‐glycolic acid) microspheres (PLGA MS) with various viscosity of PLGA polymers and investigate the RIS release profiles. Risperidone‐loaded PLGA MS were fabricated via an oil/water–type emulsion solvent evaporation method, using ethyl acetate and benzil alcohol as the dispersed solvents. The PLGA (75:25) with the viscosity of 0.82, 0.93, and 1.10 dL/g was used in the fabrication. The morphology and the degradation of the RIS‐PLGA MS were investigated with a scanning electron microscope. The distribution states of RIS in the PLGA MS were studied with differential scanning calorimetry. The residual of ethyl acetate and benzil alcohol in the resulting MS was monitored with gas chromatography. The in vitro release profiles of RIS from PLGA MS were also studied. Scanning electron microscope photographs illustrated that the obtained PLGA MS were monodisperse spheres with an average diameter of 100 μm. Gas chromatography results suggested that no residual ethyl acetate was left in the final RIS‐PLGA MS, and the residue amount of benzil alcohol was about 1%. In vitro drug release profiles from the microsphere showed a substantially sigmoidal pattern of negligible initial burst up to 24 hours and minimal release (time lag) for 14 days. After the lag phase, slow release took a place up to 30 days, and then rapid release occurred sharply for about 2 weeks. The RIS release reached equilibrium around day 50. All release profiles showed the similar trend, and no significant difference was observed among these release profiles (P > .05). This phenomenon indicated that RIS‐loaded PLGA MS with the viscosity of 0.82 to 0.93 dL/g showed the optimal release behavior. However, no obvious differences were found among the MS obtained from the viscosity of 0.82 to 1.10 dL/g. These studies provided basis for the quality control in the industrial production of PLGA MS.     

Inclusion of sulfamethoxazole in a novel CuFe2O4 nanoparticles/mesoporous silica‐based nanocomposite: Release kinetics and antibacterial activity

In this work, we aimed to improve the antibacterial activity of sulfamethoxazole (SMX) via its inclusion in a newly synthesized nanocomposite composed of CuFe₂O₄ nanoparticles and poly(vinyl alcohol)/silica‐based mesoporous materials. Characterization of this formulation using different techniques confirmed the correct synthesis and showed that this mesoporous nanocomposite had an amorphous structure with relatively high surface area of 1,620.7 m² g^?1 and mean pore diameter of 1.6576 nm. Zeta potential of the formulation was obtained to be zero which led to its higher bioavailability in comparison to pure SMX with negative zeta potential. Antibacterial property of the prepared formulation against Staphylococcus aureus and Escherichia coli was evaluated. Minimum inhibitory concentration of the SMX‐loaded mesoporous nanocomposite was considerably lower than those of pure SMX, indicating the efficient function of the mesoporous material as a delivery system. Kinetics of SMX release was also studied using zero‐order, first‐order, Higuchi, and Korsmeyer–Peppas kinetics models. According to the obtained results, the release kinetics was found to obey zero‐order model. So the possibility of sustained release of SMX from the synthesized carrier may be suggested.