Rapid microwave-assisted synthesis of gold loaded hydroxyapatite collagen nano-bio materials for drug delivery and tissue engineering application

A rapid microwave assisted facile synthetic technique was adopted to load gold nanoparticles (Au) on hydroxyapatite (HAp) surface. HAp nanoparticles were primarily synthesized by wet precipitation technique and further used for gold loading and successive collagen coating for biomedical applications. The microwave-assisted controlled synthesis technique with three heating cycles allows the very fast growing of Au seeds over HAp facets. Different sophisticated analytical techniques and spectroscopic characterization were employed to confirm the structural, chemical, and morphological features. The synthesized different concentration “Au” loaded hetero nanostructures coated with collagen (Au–HAp–Col) optimized for drug (Doxorubicin: DOX) loading and releasing purposes for biomedical applications. The maximum drug-loading efficiency of ~58.22% and a pH responsive releasing of ~53% (at pH 4.5) was obtained for 0.1?wt% Au–HAp–Col nanoparticles. To study the cytotoxic effects from the hetero nanostructures, MG-63 osteoblast-like cells were exposed to different concentration ranges on Au–HAp, Au–HAp–Col, and DOX loaded Au–HAp–Col nanoparticles. The non-toxic and bioactive properties of the synthesized nanoparticle-fabricated scaffold promotes cellular attachment, growth, and proliferation. These results indicated that optimized Au–HAp–Col nanoparticles may be promising drug delivery and scaffold materials for multifunctional biomedical applications.     

Dually Responsive Nanoparticles for Drug Delivery Based on Quaternized Chitosan

In this work, we report the fabrication and functional demonstration of a kind of dually responsive nanoparticles (NPs) as a potential drug delivery vector. The pH value, corresponding to the acidic microenvironment at the tumor site, and mannitol, to the extracellular trigger agent, were employed as the dually responsive factors. The function of dual responses was achieved by breaking the dynamic covalent bonds between phenylboronic acid (PBA) groups and diols at low pH value (pH 5.0) and/or under the administration of mannitol, which triggered the decomposition of the complex NPs and the concomitant release of anticancer drug of doxorubicin (DOX) loaded inside the NPs. The NPs were composed of modified chitosan (PQCS) with quaternary ammonium and PBA groups on the side chains, heparin (Hep), and poly(vinyl alcohol) (PVA), in which quaternary ammonium groups offer the positive charge for the cell-internalization of NPs, PBA groups serve for the formation of dynamic bonds in responding to pH change and mannitol addition, PVA furnishes the NPs with diol groups for the interaction with PBA groups and the formation of dynamic NPS, and Hep plays the roles of reducing the cytotoxicity of highly positively-charged chitosan and forming of complex NPs for DOX up-loading. A three-step fabrication process of drug-loaded NPs was described, and the characterization results were comprehensively demonstrated. The sustained drug release from the drug-loaded NPs displayed obvious pH and mannitol dependence. More specifically, the cumulative DOX release was increased more than 1.5-fold at pH 5.0 with 20 mg mL⁻¹ mannitol. Furthermore, the nanoparticles were manifested with effective antitumor efficient and apparently enhanced cytotoxicity in response to the acidic pH value and/or mannitol.     

pH‐sensitive Podophyllotoxin carrier for cancer cells specific delivery

A pH‐sensitive drug targeting system for solid tumors was established based on N‐isopropylacrylamide (NIPAAm) and chitosan conjugates. The mass ratio of NIPAAm and chitosan was adjusted to obtain super pH‐sensitive characteristic and the structure was studied by using Fourier transform infrared spectroscope to confirm the successful synthesis of the nanoparticles. The pH‐sensitive and drug release characteristics in vitro were studied as well. Human lung cancer cells A‐549 and human fibroblast were used to test the biocompatibility of blank and Podophyllotoxin (POD) loaded nanoparticles further to certificate the reliability of targeting acidic tumor extracellular pH. Results revealed that when charge ratio between NIPAAm and CS achieve 4:1(w/w), the drug‐loaded nanoparticles, which diameters ranged from 50 to 150 nm, exhibited super pH‐sensitive responses to tumor pH. Encapsulation and loading efficiencies were 63.7% and 2.4%, respectively. The cumulative release rate of POD, which significantly enhanced at pH 6.8 while decreased rapidly either below pH 6.5 or above pH 6.9 at 37°C. At pH 6.8, POD‐loaded nanoparticles showed cytotoxicity in MTT test and fluorescence microscopic study, comparable to that of free POD at the same POD concentrations, whereas at pH 7.4 there was little cytotoxicity at the tested concentration range. Thereby, the atoxic PNIPAAm‐g‐chitosan nanoparticle has the potentiality as a novel anticancer drugs carrier. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Synthesis and physicochemical characterization of amphiphilic block copolymers bearing acid-sensitive orthoester linkage as the drug carrier

Amphiphilic block copolymers bearing an acid-sensitive orthoester linkage, composed of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(γ-benzyl L-glutamate) (PBLG), were prepared as the carrier capable of selectively releasing the hydrophobic drug at the mildly acidic condition. Diblock copolymers with various lengths of PBLG were synthesized via ring opening polymerization of benzyl glutamate NCA in the presence of the acid-labile PEG as a macroinitiator. Owing to their amphiphilicities, the copolymers formed spherical micelles in aqueous conditions, and their particle sizes (22-106 nm in diameter) were dependent on the block length of PBLG. These nanoparticles were stable in the physiological buffer (pH 7.4), whereas they were readily decomposed under the acidic condition. In particular, the block copolymer with a smaller hydrophobic portion was rapidly disassembled under the acidic condition. Doxorubicin (DOX), chosen as the model anti-cancer drug, was effectively encapsulated into the hydrophobic core of the micelles using the solvent casting method. The loading efficiency depended on the hydrophobic block length of the copolymer; i.e., the longer hydrophobic block allowed for loading of larger amounts of the drug. In vitro release studies demonstrated that DOX was slowly released from the pH-sensitive micelles in the physiological buffer (pH 7.4), whereas the release rate of DOX significantly increased under the acidic condition (pH 5.0). From the in vitro cytotoxicity test, it was found that DOX-loaded pH-sensitive micelles showed higher toxicity to SCC7 cancer cells than DOX-loaded micelles without the orthoester linker. These results suggest that the amphiphilic block copolymer bearing the orthoester linkage is useful for pH-triggered delivery of the hydrophobic drug.     

Hollow Mesoporous Silica@Metal–Organic Framework and Applications for pH‐Responsive Drug Delivery

Metal?‐organic frameworks (MOFs), a new type of porous crystalline material, hold great potential in biomedical applications, such as drug delivery. However, the efficacy of drug delivery is limited by low drug loading. In this work, we synthesized hollow mesoporous silica (HMS)@MOF capsules that can be used as a pH‐responsive drug delivery system for the anticancer drug doxorubicin (DOX). DOX is loaded into the inner cavity of HMS. Zeolitic imidazolate framework‐8 (ZIF‐8) nanoparticles are then coated on the outer surface of the DOX‐loaded HMS. The obtained material is a capsule (denoted as DOX/HMS@ZIF), in which DOX is encapsulated. The DOX/HMS@ZIF can be used as an efficient pH‐responsive drug delivery system. DOX is not released under physiological conditions (pH 7.4), but is released at low pH (4–6) from DOX/HMS@ZIF. The DOX/HMS@ZIF capsule shows much higher cytotoxicity than free DOX and alters the delivery pathway for DOX in cancer cells, while the drug‐free HMS@ZIF shows excellent biocompatibility. This opens new opportunities to construct a safe and efficient delivery system for targeted molecules using pH‐responsive release for a wide range of applications.     

Formation of Multicolor Nanogels Based on Cationic Polyfluorenes and Poly(methyl vinyl ether-alt-maleic monoethyl ester): Potential Use as pH-Responsive Fluorescent Drug Carriers

In this study, we employed the copolymer poly(methyl vinyl ether-alt-maleic monoethyl ester) (PMVEMA-Es) and three fluorene-based cationic conjugated polyelectrolytes to develop fluorescent nanoparticles with emission in the blue, green and red spectral regions. The size, Zeta Potential, polydispersity, morphology, time-stability and fluorescent properties of these nanoparticles were characterized, as well as the nature of the interaction between both PMVEMA-Es and fluorescent polyelectrolytes. Because PMVEMA-Es contains a carboxylic acid group in its structure, the effects of pH and ionic strength on the nanoparticles were also evaluated, finding that the size is responsive to pH and ionic strength, largely swelling at physiological pH and returning to their initial size at acidic pHs. Thus, the developed fluorescent nanoparticles can be categorized as pH-sensitive fluorescent nanogels, since they possess the properties of both pH-responsive hydrogels and nanoparticulate systems. Doxorubicin (DOX) was used as a model drug to show the capacity of the blue-emitting nanogels to hold drugs in acidic media and release them at physiological pH, from changes in the fluorescence properties of both nanoparticles and DOX. In addition, preliminary studies by super-resolution confocal microscopy were performed, regarding their potential use as image probes.     

Effect of degree of substitution and molecular weight of carboxymethyl chitosan nanoparticles on doxorubicin delivery

The aim of this study was to evaluate the potential of carboxymethyl chitosan (CM‐chitosan) nanoparticles as carriers for the anticancer drug, doxorubicin (DOX). Different kinds of CM‐chitosan with various molecular weight (MW) and degree of substitution (DS) were employed to prepare nanoparticles through ionical gelification with calcium ions. Factors affecting nanoparticles formation in relation to MW and DS of CM‐chitosan were discussed. By the way of dynamic light scattering (DLS), TEM, and atomic force microscopy (AFM), nanoparticles were shown to be around 200–300 nm and in a narrow distribution. FTIR revealed strong electrostatic interactions between carboxyl groups of CM‐chitosan and calcium ions. DOX delivery was affected by the molecular structure of CM‐chitosan. Increasing MWs of CM‐chitosan from 4.50 to 38.9 kDa, DOX entrapment efficiency was enhanced from 10 to 40% and higher DS slightly improved the load of DOX. In vitro release studies showed an initial burst followed by an extended slow release. The DOX release rate was hindered by CM‐chitosan with high MW and DS. These preliminary studies showed the feasibility of CM‐chitosan nanoparticles to entrap DOX and the potential to deliver it as controlled release nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4689–4696, 2006     

构建pH响应性中空介孔硅纳米复合材料用于肿瘤联合治疗

以正硅酸四乙酯为原料,合成直径约为100 nm的中空介孔二氧化硅纳米颗粒(HMSN)作为药物载体,采用物理包埋法和原位还原KMnO4生成二氧化锰的方法实现对化疗药物阿霉素(DOX)和MnO2的有效负载.此外,利用肿瘤靶向性功能肽(PEG-R7-RGDS)末端的氨基与醛基修饰的HMSN(HMSN-CHO)形成席夫碱,合成pH响应性纳米载药系统(DOX/MnO2@HMSN-imide-PEG-R7-RGDS).通过TEM、激光粒度仪、FTIR和XRD对合成材料形貌、粒径、结构和组成等进行表征.结果表明,合成的HMSN呈球形中空结构.DOX/MnO2@HMSN-imide-PEG-R7-RGDS在模拟的肿瘤酸性环境(pH 5.0)中具有明显快于在模拟生理环境(pH 7.4)下的药物释放行为.此外,体外细胞实验结果表明,DOX/MnO2@HMSN-imide-PEG-R7-RGDS可以靶向进入宫颈癌细胞(HeLa)并快速释放DOX.与此同时,纳米载药颗粒中的MnO2和肿瘤细胞中高浓度谷胱甘肽(GSH)反应产生具有类芬顿反应效果的Mn2+.Mn2+与肿瘤细胞内过表达的H2O2反应生成?OH,发挥增强的化学动力学治疗.细胞毒性实验证明,化学动力学治疗与化疗相结合能对HeLa细胞产生很高的细胞毒性.     

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.     

Polyurethane/doxorubicin nanoparticles based on electrostatic interactions as pH‐sensitive drug delivery carriers

In order to obtain a pH‐sensitive delivery carrier for doxorubicin (DOX), DOX‐loaded polyurethane (PU·DOX) nanoparticles were readily prepared in water by electrostatic interactions between amphiphilic polyurethane with carboxyl pendent groups (PU‐COOH) and doxorubicin hydrochloride (DOX·HCl). The structures of the products obtained were characterized by Fourier transform infrared spectroscopy, ¹H NMR spectroscopy, gel permeation chromatography, UV–visible spectroscopy, dynamic light scattering and transmission electron microscopy. The average hydrodynamic size of the PU·DOX nanoparticles was around 182 nm with negative surface charge (?1.1 mV) and a spherical or rodlike shape. PU·DOX nanoparticles had a higher drug‐loading content of 14.1 wt%. The in vitro drug release properties of PU·DOX nanoparticles were investigated at pH 4.0, 5.0 and 7.4, respectively. PU·DOX nanoparticles exhibited a good pH‐sensitive drug release property, but there was almost no release of DOX from PU·DOX nanoparticles at pH 7.4. The in vitro cellular uptake assay and the Cell Counting Kit‐8 assay demonstrated that PU·DOX nanoparticles had a higher level of cellular internalization and higher inhibitory effects on the proliferation of human breast cancer (MCF‐7) cells than pure DOX. The enhancement of the inhibition effects resulted from increasing apoptosis‐inducing effects on MCF‐7 cells, which was related to the enhancement of Bax expression and the reduction of Bcl‐2 expression confirmed by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay, real‐time polymerase chain reaction (PCR) assay and western blot assay. © 2018 Society of Chemical Industry     

Enhanced loading of doxorubicin into polymeric micelles by a combination of ionic bonding and hydrophobic effect,and the pH-sensitive and ligand-mediated delivery of loaded drug

Folate-conjugated micelles were fabricated from amphiphilic diblock copolymers with poly(ethylene glycol) as the hydrophilic block and a random copolymer of n-butyl methacrylate and methacrylic acid as the hydrophobic block. Doxorubicin (DOX), a model drug that contains an amine group and hydrophobic moiety, was loaded with a high loading capacity into micelles by a combination of ionic bonding and hydrophobic effect. The combined interactions imparted a pH-sensitive delivery property to the system. The release rate of loaded DOX was slow at pH 7.4 (i.e., mimicking the plasma environment) but increased significantly at acidic pH (i.e., mimicking endosome/lysosome conditions). Acid-triggered drug release resulted from the carboxylate protonation of poly(methacrylic acid), which dissociated the ionic bonding between the micelles and DOX. Cellular uptake by folate receptor-overexpressing HeLa cells of the DOX-loaded folate-conjugated micelles was higher than that of micelles without folate conjugation. Thus, the DOX-loaded folate-conjugated micelles displayed higher cytotoxicity to HeLa cells.     

Intracellular pH‐sensitive dextran‐based micelles as efficient drug delivery platforms

As drug delivery systems, stimuli‐responsive polymer micelles hold great potential in cancer chemotherapeutics to improve therapeutic efficiency and eliminate organism adverse effects. Here, pH‐sensitive polymeric micelles based on dextran‐g‐benzimidazole were designed and used for intracellular anticancer drug delivery. The anticancer drug doxorubicin (DOX) was effectively loaded into the micelles via hydrophobic interactions. In vitro release studies demonstrated that the release of loaded DOX was greater and faster under acid conditions such as in carcinomatous areas (pH < 6.8) than in physiological conditions (pH 7.4). MTT assays and flow cytometric analyses showed that DOX‐loaded micelles had higher cellular proliferation inhibition towards HeLa and HepG2 cells than pH‐insensitive controls. These pH‐sensitive micelles with significant efficiency for intracellular drug release will be beneficial to the future of in vivo biomedical applications. © 2014 Society of Chemical Industry     

Acid and light dual- stimuli-cleavable polymeric micelles

In this study, acid and light dual- stimuli-responsive amphiphilic AB-type methoxy poly(ethylene glycol)-acetal-ONB-poly(4-substituted-ε-caprolactone) (MPEG-a-ONB-PXCL) diblock copolymers were synthesized using ring-opening polymerization and nucleophilic substitution reactions. The prepared copolymer features an acid-cleavable acetal group and photocleavable o-nitrobenzyl linkage between the hydrophilic MPEG and hydrophobic PXCL blocks. The design enables the diblock copolymers to respond to both acid and ultraviolet (UV) light while ensuring the minimum number of stimuli-reactive moieties in the copolymer structure. The disruption of the copolymeric micelles in aqueous solution was examined under the action of pH or UV light alone or under the combined stimulation pH and UV light. Under the combined stimulation of UV irradiation and pH, the micellar nanoparticles could dissociate; therefore, the loaded molecules could be released from the assemblies more efficiently than under either stimulus alone. The nanoparticles exhibited nonsignificant toxicity against human cervical cancer (HeLa) cells at concentrations ≤300 μg mL^?1. Doxorubicin (DOX)-loaded micelles facilitated the uptake of DOX by the HeLa cells at the initial stage. The dual stimuli-cleavable polymeric micelles show promising potential as new nanocarrier for precisely controlled release of encapsulated drug.     

PEGylated hollow pH‐responsive polymeric nanocapsules for controlled drug delivery

Novel pH‐responsive PEGylated hollow nanocapsules (HNCaps) were fabricated through a combination of distillation–precipitation copolymerization and surface thiol–ene ‘click’ grafting reaction. For this purpose, SiO₂ nanoparticles were synthesized using the Stöber approach, and then modified using 3‐(trimethoxysilyl)propyl methacrylate (MPS). Afterward, a mixture of triethyleneglycol dimethacrylate (as crosslinker), acrylic acid (AA; as pH‐responsive monomer) and MPS‐modified SiO₂ nanoparticles (as sacrificial template) was copolymerized using the distillation–precipitation approach to afford SiO₂@PAA core–shell nanoparticles. The SiO₂ core was etched from SiO₂@PAA using HF solution, and the obtained PAA HNCaps were grafted with a thiol‐end‐capped poly(ethylene glycol) (PEG) through a thiol–ene ‘click’ reaction to produce PAA‐g‐PEG HNCaps. The fabricated HNCaps were loaded with doxorubicin hydrochloride (DOX) as a model anticancer drug, and their drug loading and encapsulation efficiencies as well as pH‐dependent drug release behavior were investigated. The anticancer activity of the drug‐loaded HNCaps was extensively evaluated using MTT assay against human breast cancer cells (MCF7). The cytotoxicity assay results as well as superior physicochemical and biological features of the fabricated HNCaps mean that the developed DOX‐loaded HNCaps have excellent potential for cancer chemotherapy. © 2020 Society of Chemical Industry     

Hollow superparamagnetic iron oxide nanoshells as a hydrophobic anticancer drug carrier: intracelluar pH-dependent drug release and enhanced cytotoxicity

With curcumin and doxorubicin (DOX) base as model drugs, intracellular delivery of hydrophobic anticancer drugs by hollow structured superparamagnetic iron oxide (SPIO) nanoshells (hydrodynamic diameter: 191.9 ± 2.6 nm) was studied in glioblastoma U-87 MG cells. SPIO nanoshell-based encapsulation provided a stable aqueous dispersion of the curcumin. After the SPIO nanoshells were internalized by U-87 MG cells, they localized at the acidic compartments of endosomes and lysosomes. In endosome/lysosome-mimicking buffers with a pH of 4.5-5.5, pH-dependent drug release was observed from curcumin or DOX loaded SPIO nanoshells (curcumin/SPIO or DOX/SPIO). Compared with the free drug, the intracellular curcumin content delivered via curcumin/SPIO was 30 fold higher. Increased intracellular drug content for DOX base delivered via DOX/SPIO was also confirmed, along with a fast intracellular DOX release that was attributed to its protonation in the acidic environment. DOX/SPIO enhanced caspase-3 activity by twofold compared with free DOX base. The concentration that induced 50% cytotoxic effect (CC(50)) was 0.05 ± 0.03 μg ml(-1) for DOX/SPIO, while it was 0.13 ± 0.02 μg ml(-1) for free DOX base. These results suggested SPIO nanoshells might be a promising intracellular carrier for hydrophobic anticancer drugs.     

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.     

以壳聚糖为基质的智能电荷翻转体系用于紫杉醇的高效输送

通过在羧甲基壳聚糖纳米球(CNP)表面修饰三(2-氨基乙基)胺(TAEA)及2,3-二甲基马来酸酐(DMMA),得到针对肿瘤微酸环境响应的智能电荷翻转体系(CNP:TAEA:DMMA-纳米球),并用于难溶性抗肿瘤药物紫杉醇(PTX)的高效输送. 结果表明,所制纳米球在正常体液(pH 7.4)条件下能保留其负电性(-11 mV),从而减少被巨噬细胞J774A.1摄取;而在肿瘤部位的微酸环境(pH 6.8)下,其表面负电性(-34.8 mV)可迅速转化为正电性(+5 mV),促进被肿瘤细胞LLC摄取,提高肿瘤细胞内的药物浓度. 与市售注射剂相比,纳米球展现出良好的生物相容性,对肿瘤细胞杀伤效果也明显提高,其半抑制浓度从11.3降低至4.09 mg/mL,实现了PTX的高效输送.     

Biological Synthesis of Bioactive Gold Nanoparticles from Inonotus obliquus for Dual Chemo-Photothermal Effects against Human Brain Cancer Cells

The possibility for an ecologically friendly and simple production of gold nanoparticles (AuNPs) with Chaga mushroom (Inonotus obliquus) (Ch-AuNPs) is presented in this study. Chaga extract’s reducing potential was evaluated at varied concentrations and temperatures. The nanoparticles synthesized were all under 20 nm in size, as measured by TEM, which is a commendable result for a spontaneous synthesis method utilizing a biological source. The Ch-AuNPs showed anti-cancer chemotherapeutic effects on human brain cancer cells which is attributed to the biofunctionalization of the AuNPs with Chaga bioactive components during the synthesis process. Further, the photothermal ablation capability of the as-prepared gold nanoparticles on human brain cancer cells was investigated. It was found that the NIR-laser induced thermal ablation of cancer cells was effective in eliminating over 80% of the cells. This research projects the Ch-AuNPs as promising, dual modal (chemo-photothermal) therapeutic candidates for anti-cancer applications.     

Electrochemical copper (II) sensor based on chitosan covered gold nanoparticles

This study outlines a new sensing platform based on glassy carbon electrodes modified by gold nanoparticles (AuNPs) for the determination of heavy metal. A glassy carbon electrode was modified by chitosan stabilized AuNPs. AuNPs were prepared by reducing gold salt with a polysaccharide chitosan. Here, chitosan acted as a reducing/stabilizing agent. The AuNPs were characterized with UV–Visible absorption spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. Chitosan covered AuNPs were immobilized on the glassy carbon electrode for the determination of Cu (II) in aqueous solutions. The electrochemical determination of Cu (II) ions was performed using the differential pulse voltammetry technique. Some parameters for Cu (II) determination, such as pH, preconcentration time and electrolysis potential of Cu (II), were optimized. The detection limit was calculated as 5 × 10^?9 mol L^?1 by means of the 3:1 current-to-noise ratio. The interference of Cr(III), Fe(II), Ni(II), Pb(II), Mg(II), Zn(II), Ba(II) ions was investigated and showed a negligible effect on the electrode response. Recovery studies were carried out using tap water.     

Synthesis and characterization of PEG–PCL–PEG triblock copolymers as carriers of doxorubicin for the treatment of breast cancer

Triblock copolymers of monomethoxy poly(ethylene glycol) (mPEG) and ε‐caprolactone (CL) were prepared with varying lengths of poly(ε‐caprolactone) (PCL) compositions and a fixed length of mPEG segment. The molecular characteristics of triblock copolymers were characterized by ¹H NMR, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), and differential scanning calorimetry (DSC). These amphiphilic linear copolymers based on PCL hydrophobic chain and hydrophilic mPEG ending, which can self‐assemble into nanoscopic micelles with their hydrophobic cores, encapsulated doxorubicin (DOX) in an aqueous solution. The particle size of prepared micelles was around 40–92 nm. The DOX loading content and DOX loading efficiency were from 3.7–7.4% to 26–49%, respectively. DOX‐released profile was pH‐dependent and faster at pH 5.4 than pH 7.4. Additionally, the cytotoxicity of DOX‐loaded micelles was found to be similar with free DOX in drug‐resistant cells (MCF‐7/adr). The great amounts of DOX and fast uptake accumulated into the MCF‐7/adr cells from DOX‐loaded micelles suggest a potential application in cancer chemotherapy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010