Synthesis and characterization of a novel stimuli‐responsive magnetite nanohydrogel based on poly(ethylene glycol) and poly(N‐isopropylacrylamide) as drug carrier

A novel stimuli‐responsive magnetite nanohydrogel (MNHG), namely [poly(ethylene glycol)‐block‐poly(N‐isopropylacrylamide‐co‐maleic anhydride)₂]‐graft‐poly(ethylene glycol)/Fe₃O₄ [PEG‐b‐(PNIPAAm‐co‐PMA)₂]‐g‐PEG/Fe₃O₄, was successfully developed. For this purpose, NIPAAm and MA monomers were block copolymerized onto PEG‐based macroinitiator through atom transfer radical polymerization technique to produce PEG‐b‐(PNIPAAm‐co‐PMA)₂. The synthesized Y‐shaped terpolymer was crosslinked through the esterification of maleic anhydride units using PEG chains to afford a hydrogel. Afterward, magnetite nanoparticles were incorporated into the synthesized hydrogel through the physical interactions. The chemical structures of all synthesized samples were characterized using Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. Morphology, thermal stability, size, and magnetic properties of the synthesized MNHG were investigated. In addition, the doxorubicin hydrochloride loading and encapsulation efficiencies as well as stimuli‐responsive drug release ability of the synthesized MNHG were also evaluated. The drug‐loaded MNHG at physiological condition exhibited negligible drug release values. In contrast, at acidic (pH 5.3) condition and a little bit higher temperature (41 °C) the developed MNHG showed higher drug release values, which qualified it for cancer chemotherapy due to especial physiology of cancerous tissue in comparison with the surrounding normal tissue. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46657.     

Dual stimuli-responsive polymeric hollow nanocapsules as “smart” drug delivery system against cancer

ABSTRACT

Novel thermal- and pH-responsive hollow nanocapsules (HNCaps) were fabricated through the grafting of a thiol-end capped PNIPAAm-b-PAA by thiol-ene “click” reaction onto PMMA HNCaps. The lowest critical solution temperature (LCST) of the fabricated HNCaps was obtained as 38–40°C. The fabricated nanosystem was loaded with doxorubicin hydrochloride (Dox), and its drug loading and encapsulation efficiencies were obtained as 62 and 53%, respectively. The in vitro stimuli-responsive drug release behavior of the fabricated nanomedicine was investigated extensively. The anticancer activity of the drug-loaded HNCaps was evaluated using MTT assay against MCF7 cells. The results exhibited excellent potential of nanosystem as a drug delivery system (DDS) for cancer chemotherapy.     

Gum Acacia‐cl‐poly(acrylamide)@carbon nitride Nanocomposite Hydrogel for Adsorption of Ciprofloxacin and its Sustained Release in Artificial Ocular Solution

In the present work, a nanocomposite hydrogel is designed consisting of gum acacia, poly(acrylamide) and carbon nitride by facile microwave approach. This nanocomposite hydrogel is sensitive to environmental stimuli which is essential for its application in environmental remediation and as a drug delivery system. The effects of carbon nitride percentage and microwave Watt variation on swelling capacity of gum acacia‐cl‐poly(acrylamide)@carbon nitride (Ga‐cl‐PAM@C₃N₄) nanocomposite hydrogel are analyzed. The structural characterizations are considered by numerous techniques such as FTIR (Fourier transform infra‐red spectroscopy), X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, and elemental mapping. Batch experiment is performed for remediation of ciprofloxacin (CIP) drug from water. Various parameters such as effect of ciprofloxacin doses, Ga‐cl‐PAM@C₃N₄ nanocomposite hydrogel dosage, pH, time and temperature for adsorption of CIP on gum acacia‐cl‐poly(acrylamide)@carbon nitride nanocomposite hydrogel is examined. Maximum adsorption capacity of Ga‐cl‐PAM@C₃N₄ nanocomposite hydrogel observed is 169.49 mg g^?1 at pH 6.4. The drug loading and drug release capacity of Ga‐cl‐PAM@C₃N₄ nanocomposite hydrogel is investigated for ciprofloxacin. Drug release is monitored in artificial ocular solution (pH 8), saline (pH 5.5), acetate buffer (pH 2.2), and distilled water. Maximum drug release is observed in artificial ocular solution.     

Synthesis of hollow maghemite (-Fe2O3) particles for magnetic field and pH-responsive drug delivery and lung cancer treatment

The development of smart stimuli-responsive materials for drug delivery offers new opportunities for precise drug release and cancer chemotherapy. A combination of more than one stimuli is highly desirable to further maximize the therapy by taking the advantages of various unique merits. Herein, we employed polyethylene glycol (PEG) functionalized γ-Fe₂O₃ particles (γ-Fe₂O₃/PEG) as a novel magnetic drug carrier for doxorubicin (DOX) delivery. The results showed that the γ-Fe₂O₃/PEG exhibited excellent thermal effects under alternating magnetic field (AMF), high magneto-thermal stability, and large DOX loading capacity. Furthermore, the effects of pH and AMF on the DOX drug release were studied. It was discovered that DOX loaded γ-Fe₂O₃/PEG carriers were highly responsive to both AMF and pH, resulting in significantly improved cancer cell killing capability over a single stimulus. The magnetic and pH responsive drug delivery system provided a new opportunity to minimize the side effects and maximize the therapeutic efficiency of lung cancer treatment.     

Characterization and in vitro drug release properties of chitosan/acrylamide/gold nanocomposite prepared by gamma irradiation

A nanocomposite of (chitosan/polyacrylamide/gold) (Cs/AAm/Au) and (chitosan/polyacrylamide) (Cs/AAm) hydrogel were performed using gamma radiation and employed as a carrier for Cisplatin cancer drug. The structure and morphology were studied by FTIR and FE-SEM, respectively. XRD and TEM confirmed the formation of the nanoconposite. The average particle size ranged between 13 to 27?nm. EDX estimated that the concentration of Au⁰ nanoparticles in (Cs/AAm/Au) nanocomposite was 0.20%. Both (Cs/AAm) and (Cs/AAm/Au) have higher swelling percent and reached the swelling equilibrium within 6?h. The optimum pH of swelling was at pH 7.2. The maximum Cisplatin drug released was 33% for Cs/AAm hydrogel and 96% for Cs/AAm/Au nanocomposite at pH 7.2 through 320 and 410?min, respectively. The release mechanism was found to be followed the non-Fickian diffusion mechanism for both systems. The cytotoxicity against liver cancer (HepG2) was investigated. Cisplatin drug loaded samples (Cs/AAm) drug loaded hydrogel of concentration 100?μg/ml killed 76.4% of the cells and IC₅₀ reached 29?μg/ml whereas (Cs/AAm/Au) drug loaded nanocomposite killed 84.9 of the cells and IC₅₀ reached 22.7?μg/ml.     

pH and magnetic field responsive protein-inorganic nanohybrid conjugated with biotin: A biocompatible carrier system targeting lung cancer cells

Multi-stimuli responsive carrier systems, specifically targeting tumor cells are of high significance to improve the efficacy of cancer chemotherapy. In the present study, we have developed, characterized, and biologically evaluated magnetic casein-calcium ferrite hybrid biopolymeric carrier conjugated with biotin for targeted delivery of cinnamaldehyde to lung carcinoma. The dual stimuli-responsive carrier was successfully synthesized with small size, good stability, and high drug encapsulation efficiency. Natural drug cinnamaldehyde was encapsulated in the hybrid carrier, on which biotin was conjugated to facilitate selective cellular uptake. The prepared drug-carrier system exhibited pH-responsive drug release behavior with a higher release rate under acidic conditions, which can be effectively applied in targeted cancer chemotherapy. The superparamagnetic nature of calcium ferrite enabled magnetically-modulated drug delivery with faster drug release, reaching 85.5% within 4 h, in response to magnetic field stimulus. Kinetic modeling of drug release projected the diffusion-controlled release mechanism. Cell viability assay performed on L929 fibroblast and A549 lung cancer cells verified the biocompatibility and cytotoxicity of the developed formulation, respectively. The nanohybrid carrier significantly increased the anticancer potential of cinnamaldehyde with an 18-fold reduction in the IC₅₀ value, signifying the biotin-functionalized protein-inorganic nanohybrid as an efficient multifunctional platform for targeted drug delivery.     

Magnetite/poly(D,L-lactide-co-glycolide) and hydroxyapatite/poly(D,L-lactide-co-glycolide) prepared by W/O/W emulsion technique for drug carrier: Evaluation of in vitro release of dexamethasone from composite nanoparticles

Biocompatible polymeric carriers containing inorganic materials for delivering therapeutic agents to a targeted site are promising candidate for drug delivery. Two nanocomposite nanoparticles, magnetite/poly(D,L-lactide-co-glycolide) and hydroxyapatite/poly(D,L-lactide-co-glycolide) (Fe₃O₄/PLGA and HAp/PLGA, respectively), with different weight ratios of inorganics to polymer and different polymer molecular weights were prepared by water-in-oil-in-water (W/O/W) emulsion technique to determine incorporation and in vitro release profile of the small molecule drugs water-insoluble dexamethasone acetate (DEX-Ac) and water-soluble dexamethasone phosphate (DEX-P). The in vitro release for DEX-Ac nanoparticles showed an initial burst release followed by a continuous slower release, whereas DEX-P nanoparticles showed only rapid initial release behavior.     

PEGylated polylysine derived copolymers with reduction‐responsive side chains for anticancer drug delivery

Reduction‐responsive drug delivery systems have recently gained intense attention in intracellular delivery of anticancer drugs. In this study, we developed a PEGylated polypeptide, poly(ethylene glycol)‐block‐poly(?‐propargyloxycarbonyl‐l ‐lysine) (PEG₁₁₃‐b‐PPAL), as a novel clickable substrate for conjugation of reduction‐responsive side chains for antineoplastic drug delivery. PEG₁₁₃‐b‐PPAL was synthesized through ring‐opening polymerization of alkyne‐containing N‐carboxyanhydride monomers. A designed disulfide‐containing side chain was introduced onto the PEGylated polypeptide by click reaction. The obtained copolymer PEG₁₁₃‐b‐P(Lys‐DSA) formed micelles by self‐assembly, which exhibited reduction‐responsive behavior under the stimulus of 10 mmol L^–1 glutathione (GSH) in water. A small molecule intermediate, compound 2 , was used as a model to investigate the thiol reduction mechanism of PEG₁₁₃‐b‐P(Lys‐DSA) copolymers. The anticancer drug doxorubicin (DOX) was then loaded into the micelles with a drug loading content of 6.73 wt% and a loading efficiency of 40.3%. Both the blank and the drug‐loaded micelles (DOX‐loaded polylysine derived polymeric micelles (LMs/DOX)) adopted a spherical morphology, with average diameters of 48.0 ± 13.1 and 63.8 ± 20.0 nm, respectively. The in vitro drug release results indicated that DOX could be released faster from the micelles by the trigger of GSH in phosphate buffered saline. Confocal laser scanning microscopy and flow cytometer analysis further proved the intracellular delivery of DOX by LMs/DOX and their GSH‐sensitive release behavior. A 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide assay showed that the polymers exhibited negligible cytotoxicity towards normal L929 cells or cancer MCF‐7 cells with a treated concentration up to 1.0 mg mL^–1. In conclusion, our synthesized biocompatible and biodegradable PEGylated polypeptides hold great promise for intracellular antineoplastic drug delivery. © 2019 Society of Chemical Industry     

Ultrasonochemical‐assisted fabrication and evaporation‐ induced self‐assembly (EISA) of POSS‐SiO2@Ag core/ABA triblock copolymer nanocomposite film

Poly(ethylene glycol)‐octafunctionalized polyhedral oligomeric silsesquioxane (POSS) (M_n = 5576.6 g/mol) alloying agent stabilized amphiphilic silica@silver metalloid nanocomposite blended with a triblock copolymer poly(p‐dioxanone‐co‐caprolactone)‐block‐poly(ethylene oxide)‐block‐poly(p‐dioxanone‐co‐caprolactone) (POSS‐SiO₂@Ag/PPDO‐co‐PCL‐b‐PEG‐b‐PPDO‐co‐PCL) has been synthesized in both water and in organic medium utilizing ultrasonochemical reaction. The POSS stabilized pre‐made metalloid was successfully dispersed in amphiphilic PPDO‐co‐PCL‐b‐PEG‐b‐PPDO‐co‐PCL (ABA) triblock copolymer matrix of molecular weight 45.9 × 10⁴ g/mol. The mechanism of synthesis of high concentration of SiO₂@Ag nanocomposite from TEOS/AgNO₃ (in the presence of NH₄OH as catalyst/NaBH₄ as reductant) nonmetal/metal precursors and the successful EISA of POSS‐SiO₂@Ag/ABA nanocomposite into films has been discussed. The successful synthesis of metalloid nanocomposite was morphologically accessed by field emission‐scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Surface plasmon resonance was ensured from UV–visible spectral analysis. Identity and the crystallinity of as prepared nanocomposite were studied by X‐ray diffractometer. Structural and luminescence properties of the nanocomposite were examined by Fourier transform infrared spectroscopy and photoluminescence. Thermogravimetric analysis was carried out to study the thermal stability of the resulting hybrid nanocomposite. The resultant inorganic–organic nanocomposite can be easily suspended in water and would be useful in variety of applications. POLYM. COMPOS., 31:1620–1627, 2010. © 2009 Society of Plastics Engineers     

Liver‐targeting doxorubicin‐conjugated polymeric prodrug with pH‐triggered drug release profile

The aim of the research presented was to develop a potential liver‐targeting prolonged‐circulation polymeric prodrug of doxorubicin (Dox) with a pH‐triggered drug release profile. In particular, linear dendritic block copolymers composed of polyamidoamine dendrimer (PAMAM) and poly(ethylene glycol) (PEG; number‐average molecular weight of 2000 g mol^?1) with or without galactose (Gal) were synthesized. Dox was coupled to the copolymers via an acid‐labile hydrazone linker. These prodrugs, designated Gal‐PEG‐b‐PAMAM‐Dox_n and mPEG‐b‐PAMAM‐Dox_m, showed accelerated Dox release as the pH decreased from 8.0 to 5.6. Cytotoxicity of the prodrugs was lower than that of free Dox due to the gradual drug release nature. Compared to mPEG‐b‐PAMAM‐Dox_m, Gal‐PEG‐b‐PAMAM‐Dox_n showed rather high cytotoxicity against Bel‐7402, suggestive of its galactose receptor‐mediated enhanced tumor uptake. This galactose receptor‐mediated liver‐targeted profile was further confirmed by the prolonged retention time in hepatoma tissue monitored using magnetic resonance imaging. Gal‐PEG‐b‐PAMAM‐Dox_n showed better in vivo antitumor efficacy than free Dox, suggesting its great potential as a polymeric antitumor prodrug. Copyright © 2010 Society of Chemical Industry     

A magnetic polypeptide nanocomposite with pH and near-infrared dual responsiveness for cancer therapy

A magnetic polypeptide nanocomposite with pH and near-infrared (NIR) dual responsiveness was developed as a drug carrier for cancer therapy, which was prepared through the self-assembly of Fe₃O₄ superparamagnetic nanoparticles, poly(aspartic acid) derivative (mPEG-g-PDAEAIM) and doxorubicin (DOX) in water. Fe₃O₄ nanoparticles were prepared to provide the superparamagnetic core of nanocomposites for tumor targeting via chemical co-precipitation. The protonable imidazole groups of mPEG-g-PDAEAIM with a pKa of ~7 were accountable for the pH-responsiveness of nanocomposites. The photothermal effect of nanocomposites under the irradiation of NIR laser was induced via the interactions between dopamine groups of mPEG-g-PDAEAIM and Fe₃O₄ superparamagnetic nanoparticles to trigger the drug release. NMR, FT-IR, TEM, hysteresis loop analysis and MRI were utilized to characterize the materials. The DOX loaded nanocomposites exhibited pH-responsive and NIR dependent on/off switchable release profiles. The nanocomposites without drug loading (Fe₃O₄@mPEG-g-PDAEAIM) showed excellent biocompatibility while DOX loaded nanocomposites caused MCF-7 cells’ apoptosis due to the photothermal/chemotherapy combination effects. Overall, the pH and near-infrared dual responsive magnetic nanocomposite had a great potential for cancer therapy.     

Gold deposition on Fe3O4/(co)Poly(N‐octadecyl methacrylate) hybrid particles to obtain nanocomposites With ternary intrinsic features

Here, nanocomposite particles with three domains including magnetite nanoparticles, poly(N‐octadecyl methacrylate) (PODMA) or poly(N‐octadecyl methacrylate‐co‐1‐vinylimidazole) (P(ODMA‐co‐VIMZ)), and gold nanoparticles were prepared. Fe₃O₄ nanoparticles with narrow particle size distribution were prepared through a synthetic route in an organic phase in order to achieve good control of the size and size distribution and prevent their aggregation during their preparation. These magnetite nanoparticles, ～ 5 nm in size, were then encapsulated and well‐dispersed in PODMA and P(ODMA‐co‐VIMZ) matrices via a miniemulsion polymerization process to obtain the corresponding nanocomposite particles. The results revealed that Fe₃O₄ nanoparticles were encapsulated and did not migrate towards the monomer/water interface during polymerization. The resulting latex was used as a precursor for the adsorption of Au³⁺ ions on the surface of the polymeric particles and subsequent reduction to produce Fe₃O₄/P(ODMA‐co‐VIMZ)/Au nanocomposite particles. The morphology of the particles from each step was fully characterized by TEM and AFM, and the results of DLS analysis showed their size and size distribution. Measurement of magnetic properties illustrated the superparamagnetic characteristic of the products and it was observed that the encapsulation process and deposition of gold had no effect on the magnetic properties of the resulting particles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of Graphene Oxide/Iron Oxide/Au Nanocomposite for Quercetin Delivery

This study focused on developing a superparamagnetic graphene oxide-based nanocomposite consisting of iron oxide (IO) and gold nanoparticles for quercetin delivery. For this purpose, the structure and morphology of the designed nanocomposite (GO/IO/Au) were investigated by several characterization methods such as fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, vibrating-sample magnetometer (VSM) analysis, field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). Then, the biocompatibility of the synthesized nanocomposite was studied by Brine shrimp Artemia lethality assay, red blood cell hemolysis assay, and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Moreover, the GO/IO/Au nanocomposite efficiency as an anticancer drug delivery system was evaluated in vitro conditions. The results showed that the designed nanocomposite is highly biocompatible and possesses a favorable magnetization (M_s?=?29.2 emu.g^?1) making it a good candidate for biomedical applications. Also, it was confirmed that GO/IO/Au nanocomposite is a potent drug carrier that can effectively deliver quercetin to cancer cells.

     

Hexamethylene diamine/carboxymethyl cellulose grafted on magnetic nanoparticles for controlled drug delivery

In this study, chemically modified iron oxide nanoparticles with super paramagnetic behavior and biodegradable properties were prepared through the reaction of a polymeric layer with surface hydroxyl functional groups of magnetic nanoparticles (MNP). For this purpose firstly, MNP was grafted with hexamethylene diisocyanate. Then, carboxymethyl cellulose which was modified with the hexamethylenediamine (mCMC) as a shell was coated and reacted simultaneously on MNP-grafted hexamethylene diisocyanate to form a polymeric core–shell (MNP/mCMC). The structural, morphological, thermal, and magnetic properties of the synthesized magnetite nanocomposite were confirmed by Fourier transform infrared spectrophotometer, thermal gravimetric analysis, X-ray diffraction, vibrating sample magnetometer, and scanning electron microscopy. The size of the resulting MNP/mCMC was approximately between 70 and 120 nm. Doxorubicin (DOX) as a model anticancer drug was used. The in vitro release of DOX from the MNP/mCMC was investigated and indicated that the release speed of the DOX could be well controlled. Release profiles of the DOX and its loading capacity were determined by ultraviolet–visible spectroscopy absorption measurement at λ _max 483 nm. The obtained results suggest that the prepared magnetite nanocomposite would be beneficial as a targeted anti-tumor drug carrier for pharmaceutical applications.     

Magnetic nanoparticles embedded in pectin‐based hydrogel for the sustained release of diclofenac sodium

A supermagnetic polysaccharide‐based nanocomposite gel has been developed as a potential drug delivery system. The gel was made via graft copolymerization of 2‐acrylamido‐2‐methylpropanesulfonic acid on pectin using ammonium peroxodisulfate as an initiator and N,N‐methylenebisacrylamide as a crosslinker under microwave irradiation. The magnetic nanoparticles (MNPs) were incorporated within the gel network via an in situ method of diffusion of Fe²⁺/Fe³⁺ followed by reduction with ammonia solution. The graft copolymer gel and its nanocomposite were characterized using attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and transmission electron microscopy. The magnetic properties of the nanocomposite were measured using a vibrating sample magnetometer and mechanical properties using a tensile compressive tester. The gel was evaluated for adsorption and release of the drug diclofenac sodium. The presence of MNPs is observed to enhance significantly the mechanical properties, swelling capacity, drug loading and release ability of the graft polymer gel. The increased porosity of the gel network and higher surface area of MNPs allowed for 20% higher adsorption of diclofenac sodium molecules compared to the parent nonmagnetic gel. About 95% of the loaded drug was released from the MNP‐containing gel. The drug release pattern followed first‐order kinetic model and the Higuchi square root model, indicating swelling‐controlled diffusion to be the mode of drug release. © 2018 Society of Chemical Industry     

Dual stimuli-responsive poly(succinyloxyethylmethacrylate-b-N-isopropylacrylamide) block copolymers as nanocarriers and respective application in doxorubicin delivery

Stimuli-responsive nanostructures were developed as anticancer drug delivery carriers. To this end, poly(2-hydroxyethylmethacrylate)-b-(N-isopropylacrylamide) (poly(HEMA-b-NIPAAm)) diblock copolymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization with two ratios remarked with (1) and (2). Based on gel permeation chromatography, the molecular weights of synthesized diblock copolymers were 17802 (1) and 13090 (2) g?mol^?1. The pH- and thermoresponsive poly(succinyloxyethylmethacrylate-b-N-isopropylacrylamide) (poly)SEMA-b-NIPAAm)) diblock copolymers were obtained by reacting poly(HEMA-b-NIPAAm) with excess succinic anhydride in pyridine under mild conditions. Developed micelles with poly(SEMA-b-NIPAAm) (1) and poly(SEMA-b-NIPAAm) (2) diblock copolymers around pH of 3–4 at 25°C demonstrated the critical micelles concentrations (CMCs) of 0.026 and 0.019?g?L^?1, respectively. The average sizes of poly)SEMA-b-NIPAAm) micelles using dynamic light scattering (DLS) measurements at pH 3.0, 6.0, and 9.0 were 240, 190, and 150?nm, respectively. The core-shell poly(SEMA-b-NIPAAm) micelles at pH 3 and 9 were 100–200?nm. The lower critical solution temperature (LCST) of poly)SEMA-b-NIPAAm) sample was determined to be 40°C by ultraviolet-visible (UV-vis) spectroscopy. The micelles of diblock copolymers were formed to enhance the drug solubility in aqueous solutions. Doxorubicin hydrochloride (DOX)-loading capacity was 99.1%. The release of DOX acted better at 42°C compared to 40°C. The results confirmed that pH- and temperature-dependent release of this drug carrier was particularly useful and important for the anticancer drug delivery at the tumor-like environment. Therefore, the biocompatibility of diblock copolymer was confirmed by assessing survival rate of breast cancer cell line (MCF7) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The synthesized nanoparticles would have an excellent potential as anticancer drug delivery.     

Redox and pH dual-responsive biodegradable mesoporous silica nanoparticle as a potential drug carrier for synergistic cancer therapy

Multifunctional mesoporous silica-based nanocarriers able to efficiently encapsulate drugs for stimuli-responsive release and display rapid biodegradation are highly desirable. In this work, we dope disulfide bonds and calcium into silica framework by one step method to obtain a redox and pH dual-responsive biodegradable mesoporous silica nanoparticle (BT-Ca-MSN) as a potential drug carrier for synergistic cancer therapy. TEM and ICP-OES are used to assess the biodegradation behavior of BT-Ca-MSN. The results show that BT-Ca-MSN can significantly biodegrade in a concurrent reductive and acidic environment due to the simultaneous disulfide bonds cleavage and Ca²⁺ release. In addition, BT-Ca-MSN shows efficient drug loading capacity and significant biodegradation-mediated drug release. Moreover, the in-vitro cytotoxicity indicates that BT-Ca-MSN can not only exhibit significant cancer cell killing effect without obvious toxicity on healthy cells via the way of released Ca²⁺-mediated apoptosis, but also can combine with its loaded doxorubicin hydrochloride for synergistic cancer therapy. This work demonstrates that BT-Ca-MSN is a promising platform as drug carrier, providing a paradigm to rationally design biodegradable silica-based carriers for highly efficient cancer therapy.     

Magnetically Controlled Carbonate Nanocomposite with Ciprofloxacin for Biofilm Eradication

Biofilms are the reason for a vast majority of chronic inflammation cases and most acute inflammation. The treatment of biofilms still is a complicated task due to the low efficiency of drug delivery and high resistivity of the involved bacteria to harmful factors. Here we describe a magnetically controlled nanocomposite with a stimuli-responsive release profile based on calcium carbonate and magnetite with an encapsulated antibiotic (ciprofloxacin) that can be used to solve this problem. The material magnetic properties allowed targeted delivery, accumulation, and penetration of the composite in the biofilm, as well as the rapid triggered release of the entrapped antibiotic. Under the influence of an RF magnetic field with a frequency of 210 kHz, the composite underwent a phase transition from vaterite into calcite and promoted the release of ciprofloxacin. The effectiveness of the composite was tested against formed biofilms of E. coli and S. aureus and showed a 71% reduction in E. coli biofilm biomass and an 85% reduction in S. aureus biofilms. The efficiency of the composite with entrapped ciprofloxacin was higher than for the free antibiotic in the same concentration, up to 72%. The developed composite is a promising material for the treatment of biofilm-associated inflammations.     

Encapsulation of curcumin by methoxy poly(ethylene glycol‐b‐aromatic anhydride) micelles

Suitable carrier systems for sustained release of curcumin were studied by using the self‐assembled polymeric micelles. Poly(ethylene glycol) methyl ether and poly(aromatic anhydride) were used as the hydrophilic and hydrophobic blocks, respectively, in forming amphiphilic diblock copolymers. Four different types of polymers methoxy poly(ethylene glycol‐ b‐1,3‐bis(p‐carboxyphenoxy)propane) (mPEG₅₀₀₀CPP, mPEG₂₀₀₀CPP), methoxy poly(ethylene glycol‐b‐1,6‐bis(p‐carboxyphenoxy)hexane) (mPEG₅₀₀₀CPH, mPEG₂₀₀₀CPH) were synthesized via melt condensation approach. Micelles were formed at very low polymer concentration with stable hydrophobic cores. The particle sizes of micelles remained stable during degradation period. All four different polymeric micelles showed low cytotoxicity toward human fibroblasts cells and can kill cancer cells in very low concentrations. High loading efficiency and drug content were observed in curcumin‐loaded micelles. Curcumin showed mild initial burst (30% of drug loading in the first 24 h) when released from the micelles and its release was sustained for at least 18 days. These micelles, especially those of mPEG₅₀₀₀CPP, show potential to serve as the delivery vehicles for sustained release of curcumin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Synthesis and characterization of magnetite (Fe3O4)—Polyvinyl alcohol‐based nanocomposites and study of superparamagnetism

The aim of this investigation was to design iron oxide containing nanocomposites which could display superparamagnetic behavior and thus find application in biomedical and allied fields. To achieve the proposed objectives methyl methacrylate was polymerized by a redox system comprising of metabisulphite and persulphate in the immediate presence of a crosslinker, N,N′‐methylene bis acrylamide and a preformed polymer, i.e., polyvinyl alcohol. Into the prepared polymer matrix nanosized magnetite (Fe₃O₄) particles were evenly dispersed by in situ precipitation of Fe²⁺/Fe³⁺ ions. The nanocomposite materials were characterized by techniques like FTIR, SEM, TEM, XRD, and DSC. The magnetic behavior of nanocomposites and bulk magnetite particles was studied under varying applied magnetic fields and their superparamagnetic property was examined. The iron‐oxide polymer nanocomposites were also studied for microhardness. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers