Synthesis and characterization of pH-dependent glycol chitosan and dextran sulfate nanoparticles for effective brain cancer treatment

A novel drug delivery system for the treatment of brain tumors was formulated by methotrexate (MTX)-loaded polymeric nanoparticles (NPs) based on Glycol chitosan (GCS) and Dextran sulfate (DS). The physicochemical properties of resulting particles were investigated, evidencing the contribution of these nanoparticles for brain targeting. In vitro release of MTX was also evaluated. The GCS-DS nanoparticles have been developed based on the modulation of ratio show promise as a system for controlled delivery of the drug to the brain.     

Distributed parameters deterministic model for treatment of brain tumors using Galerkin finite element method

In this paper, we present a distributed parameters deterministic model for treatment of brain tumors using Galerkin finite element method. The dynamic model comprises system of three coupled reaction-diffusion models, involving the tumor cells, the normal tissues and the drug concentration. An optimal control problem is formulated with the goal of minimizing the tumor cell density and reducing the side effects of the drug. A distributed parameters method based on the application of variational calculus is used on an integral-Hamiltonian, which is then used to obtain an optimal coupled system of forward state equations and backward co-state equations. The Galerkin finite element method is used to realistically represent the brain structure as well as to facilitate computation. Finally a three-dimensional test case is considered and partitioned into a set of spherical finite elements, using tri-linear basis functions, except for the elements affected by singularities of polar and azimuthal angles, as well as the origin.     

Experimental manipulations of afferent immune responses influence efferent immune responses to brain tumors

Tumors grow more readily in the brain than in the periphery, in part due to immune privilege. Differences in both afferent and efferent components of the immune response contribute to this lower level of responsiveness. On the afferent side, despite the lack of lymphatic vessels in the brain, antigens from brain arrive in lymph nodes and spleen by several routes, and the route taken may influence the type of response generated. Work with viruses and soluble antigens in mice has shown that the intracerebral location and the volume of the inoculation influence the strength of the cytotoxic T cell response. We examined whether these factors influence the T cell response against experimental brain tumors in mice. Placement of tumor cells in the cerebral ventricles instead of the parenchyma generated an immune response sufficient to increase survival time. A large volume of an intraparenchymal infusion of tumor cells caused spread of cells to the ventricles, and resulted in longer survival time relative to a small volume infusion. Infusion of the same dose of radiolabeled tumor cells in either a small volume or a large volume allowed tracking of potential tumor antigens to the periphery. Both modes of infusion resulted in similar levels of radioactivity in blood, spleen and kidney. Unexpectedly, cells infused intraparenchymally in a small volume, compared to a large volume, resulted in (1) more radioactivity in cervical lymph nodes (parotid and deep cervical lymph nodes), (2) a greater number of CD11b+/Gr1+ myeloid suppressor cells in the tumors, and (3) fewer CD8+ cells within the tumor mass. Consistent with these observations, providing a stronger afferent stimulus by giving a concurrent subcutaneous injection of the same tumor cells infused into the brain increased CD8+ T cell infiltration of the tumor in the brain. These results suggest that the immune response elicited by antigens that drain predominantly to the cervical lymph nodes may be less effective than responses elicited at other lymph nodes, perhaps due to immunosuppressive cells. Directing therapies to the optimal peripheral sites may improve immune responses against brain tumors.     

Design considerations for PAMAM dendrimer therapeutics

We have previously shown that methotrexate (MTX) conjugated to a cancer-specific poly amido amine (PAMAM) dendrimer has a higher therapeutic index than MTX alone. Unfortunately, these therapeutics have been difficult to advance because of the complicated syntheses and an incomplete understanding of the dendrimer properties. We wished to address these obstacles by using copper-free click chemistry to functionalize the dendrimer scaffolds and to exploring the effects of two dendrimer properties (the targeting ligand and drug linkage) on cytotoxicity. We conjugated either ester or amide-linker modified MTX to dendrimer scaffolds with or without folic acid (FA). Because of multivalency, the FA and MTX functionalized dendrimers had similar capacities to target the folate receptor on cancer cells. Additionally, we found that the ester- and amide-linker modified MTX compounds had similar cytotoxicity but the dendrimer–ester MTX conjugates were much more cytotoxic than the dendrimer–amide MTX conjugates. These results clarify the impact of these properties on therapeutic efficacy and will allow us to design more effective polymer therapeutics.     

Engineered magnetic core shell nanoprobes:Synthesis and applications to cancer imaging and therapeutics

Magnetic core shell nanoparticles are composed of a highly magnetic core material surrounded by a thin shell of desired drug, polymer or metal oxide. These magnetic core shell nanoparticles have a wide range of applications in biomedical research, more specifically in tissue imaging, drug delivery and therapeutics. The present review discusses the up-to-date knowledge on the various procedures for synthesis of magnetic core shell nanoparticles along with their applications in cancer imaging, drug delivery and hyperthermia or cancer therapeutics. Literature in this area shows that magnetic core shell nanoparticle-based imaging, drug targeting and therapy through hyperthermia can potentially be a powerful tool for the advanced diagnosis and treatment of various cancers.     

巨噬细胞装载纳米颗粒用于药物递送

目的:活细胞药物递送系统具有主动靶向至肿瘤部位,防止被免疫系统清除等诸多优势。本文提供了一种巨噬细胞负载纳米颗粒的递送方法,并探讨不同载药量对巨噬细胞的活性以及运动性的影响。方法:通过超声乳化法制备包载阿霉素的DOX@PLGA纳米颗粒。纳米粒度分析仪测量粒径和表面电位,透射电镜观察纳米颗粒形态。将DOX@PLGA纳米颗粒与巨噬细胞共同孵育,即得到负载DOX@PLGA纳米颗粒的巨噬细胞用以药物递送。然后通过CCK-8法、LDH法以及细胞迁移实验检测不同载药量情况下细胞活力水平、细胞损伤程度以及细胞运动性。结果:制备的DOX@PLGA纳米颗粒呈圆形或椭圆形,粒径为109.2±2.3 nm;表面电位为-45.0±2.0 m V;载药量为4.61%。当单个巨噬细胞负载0.15 pg DOX时细胞存活率为:71.5±4.4(%);细胞损伤率为:26.3±1.8(%);迁移率为:61.6±5.7(%)。结论:成功制备巨噬细胞负载DOX@PLGA纳米颗粒的递药系统,载药量适当的情况下载体细胞依然具有良好的活性和运动性。     

The blood-brain barrier in brain homeostasis and neurological diseases

Brain endothelial cells are unique among endothelial cells in that they express apical junctional complexes, including tight junctions, which quite resemble epithelial tight junctions both structurally and functionally. They form the blood-brain-barrier (BBB) which strictly controls the exchanges between the blood and the brain compartments by limiting passive diffusion of blood-borne solutes while actively transporting nutrients to the brain. Accumulating experimental and clinical evidence indicate that BBB dysfunctions are associated with a number of serious CNS diseases with important social impacts, such as multiple sclerosis, stroke, brain tumors, epilepsy or Alzheimer's disease. This review will focus on the implication of brain endothelial tight junctions in BBB architecture and physiology, will discuss the consequences of BBB dysfunction in these CNS diseases and will present some therapeutic strategies for drug delivery to the brain across the BBB.     

载药纳米粒作为脑靶向给药系统的研究

血脑屏障使大部分的活性药物很难由血液进入脑内发挥作用。载药纳米粒具有脑靶向性,可显著提高药物在脑内浓度,成为药物突破血脑屏障的有效途径。本文综述了近年来载药纳米粒透过血脑屏障的研究进展,并对纳米粒载中药入脑提出展望。     

载药纳米粒作为脑靶向给药系统的研究

血脑屏障使大部分的活性药物很难由血液进入脑内发挥作用。载药纳米粒具有脑靶向性,可显著提高药物在脑内浓度,成为药物突破血脑屏障的有效途径。本文综述了近年来载药纳米粒透过血脑屏障的研究进展,并对纳米粒载中药入脑提出展望。     

Rigid nanoparticle-based delivery of anti-cancer siRNA: Challenges and opportunities

Gene therapy is a promising strategy to treat various genetic and acquired diseases. Small interfering RNA (siRNA) is a revolutionary tool for gene therapy and the analysis of gene function. However, the development of a safe, efficient, and targetable non-viral siRNA delivery system remains a major challenge in gene therapy. An ideal delivery system should be able to encapsulate and protect the siRNA cargo from serum proteins, exhibit target tissue and cell specificity, penetrate the cell membrane, and release its cargo in the desired intracellular compartment. Nanomedicine has the potential to deal with these challenges faced by siRNA delivery. The unique characteristics of rigid nanoparticles mostly inorganic nanoparticles and allotropes of carbon nanomaterials, including high surface area, facile surface modification, controllable size, and excellent magnetic/optical/electrical properties, make them promising candidates for targeted siRNA delivery. In this review, recent progresses on rigid nanoparticle-based siRNA delivery systems will be summarized.     

Cancer Detection and Treatment: The Role of Nanomedicines

Nanotechnology is a field which has been at the forefront of research over the past two decades. The full potential of nanotechnology has yet to be fully realized. One subset of nanotechnology that has emerged is nanomedicine, which has been able to exploit the unique properties of nano-sized particles for therapeutics. Nanomedicine has the potential to increase the specific treatment of cancer cells while leaving healthy cells intact through the use of novel nanoparticles to seek and treat cancer in the human body. However, there are undoubtedly toxicities, which have not yet been fully elucidated. Various nano-carriers such as nanoshells, nanocrystals, nanopolymers, quantum dots, and dendrimers, and their role in early cancer detection and treatment have been discussed in this article.     

Improved anti-tumoral capacity of mixed and pure anti-oestrogens in breast cancer cell xenografts after their administration by entrapment in colloidal nanosystems

Anti-oestrogens (AEs) are currently used for treating hormone-dependent breast cancers. They specifically bind to oestrogen receptors (ERs) and inhibit their transactivation capacity. However, ERs are present in various other tissues in which AEs may have either a beneficial or detrimental action. AE administration via systems targeting breast tumours may be an important therapeutic improvement. Thus, several biodegradable drug delivery systems containing either “mixed” (4-hydroxytamoxifen - 4-HT) or “pure” (RU 58668 - RU) AEs were prepared. Liposomes and nanospheres (NS, composed of non-toxic and biodegradable lipids and poly(d,l-lactic acid) incorporated up to 1 and 0.5 mM AE, respectively. Nanocapsules (NCs) in which an oily core solubilises the AE incorporated no more than 0.02 mM of the drug. PEG-functionalised nanoparticles survived longer in plasma and had better controlled release of the drug. The small size of the vectors (100–250 nm) was compatible with their extravasation through the discontinuous endothelium of tumour vasculature, allowing their accumulation in MCF-7 cell xenografts and leading to a prolonged exposure of the tumour to AEs. In these tumours and in MCF-7/ras xenografts, RU-NS and RU-NC (6.5 mg/kg/week and 0.27 mg/kg/week, respectively, doses at which free RU had a very weak effect), both inhibited tumour growth. Entrapped RU significantly induced involution of tumours and strongly induced apoptosis in tumour cells, concomitantly with inhibiting tumour angiogenesis. 4-HT-nanoparticles also arrest oestradiol-induced tumour growth, inducing apoptosis and inhibiting angiogenesis. However, unlike RU-nanoparticles, they did not promote ER subtype loss in tumour cells. Subcutaneous administration of both RU- and 4-HT-NS in MCF-7 xenografts strongly arrested tumour growth for prolonged periods and RUNS decreased the number of tumour epithelial cells. Analysis of the proteins involved in cell cycle proliferation and apoptosis confirmed that RU-nanoparticles were more efficient than 4-HT-nanoparticles. Their lack of toxicity and high anti-tumour potency that affects only tumour cells in the xenograft models mean these AE-loaded colloidal systems are a breakthrough in hormone-dependent breast cancer treatment.     

Functionalized carbon nanotubes as emerging nanovectors for the delivery of therapeutics

Functionalized carbon nanotubes (f-CNT) are emerging as a new family of nanovectors for the delivery of different types of therapeutic molecules. The application of CNT in the field of carrier-mediated delivery has become possible after the recent discovery of their capacity to penetrate into the cells. CNT can be loaded with active molecules by forming stable covalent bonds or supramolecular assemblies based on noncovalent interactions. Once the cargos are carried into various cells, tissues and organs they are able to express their biological function. In this review, we will describe the potential of f-CNT to deliver different types of therapeutic molecules.     

刺激响应型DNA水凝胶的性质及其应用 *

DNA水凝胶作为一种生物合成分子,既具有DNA分子的特异性,生物可降解性和分子识别等特性,又具有水凝胶的高亲水性等特征.刺激响应型DNA水凝胶主要是在环境因素的刺激下,利用常规DNA序列经Watson-Crick碱基互补配对形成的DNA分支结构或多种功能核酸的特殊DNA序列形成的i-motif结构;T-A·T三螺旋结构,C-G·C ⁺三螺旋结构及G-四链体结构等对环境的响应行为使水凝胶形成及应用.近年来,刺激响应型DNA水凝胶因其在温度,pH,光,金属离子,生物分子等单刺激因素,以及光热,金属离子,有机物,温度与pH等多刺激因素下的独特应答性质,在生物传感,生物成像,药物递送,生物材料等方面得到了广泛的应用.综述了刺激响应型DNA水凝胶的形成方法,分类及其核酸来源,形成后的表征手段以及在环境刺激下的响应行为与应用,概括了目前刺激响应型DNA水凝胶的研究热点,并就其未来发展趋势做出了预测.     

Preparation and properties of a pH/temperature-responsive carboxymethyl chitosan/poly(N-isopropylacrylamide)semi-IPN hydrogel for oral delivery of drugs

Thermo- and pH-responsive semi-IPN polyampholyte hydrogels were prepared by using carboxymethylchitosan and poly(N-isopropylacrylamide) with N,N'-methylenebisacrylamide (BIS) as the crosslinking agent. The swelling characteristics of these hydrogels at distinct compositions as a function of pH and temperature were investigated. It was found that the semi-IPN hydrogels demonstrated the pH- and temperature-responsive nature of the materials, and it also showed good reversibility. The study on the release of coenzyme A (CoA) showed that within 24h the cumulative release ratio of CoA was 22.6% in pH 2.1 solution and 89.1% in pH 7.4 solution at 37 degrees C, respectively. The release rate of CoA was higher at 37 degrees C than 25 degrees C in a pH 7.4 buffer solution. An increased release rate of CoA was observed with the content of carboxymethylchitosan increasing in the hydrogel at 25 degrees C in pH 7.4 solution. These results show that semi-IPN hydrogel seems to be of great promise in pH-temperature oral drug delivery systems.     

Preparation and characterization of magnetic gold nanoparticles to be used as doxorubicin nanocarriers

Magnetic targeted drug delivery (MTD), using magnetic gold nanoparticles (Fe₃O₄@Au NPs) conjugated with an anti-cancer drug is a promise modality for cancer treatment. In this study, Fe₃O₄@Au NPs were prepared and functionalized with thiol-terminated polyethylene glycol (PEG), then loaded with anti-cancer drug doxorubicin (DOX). The physical properties of the prepared NPs were characterized using different techniques. Transmission electron microscopy (TEM) revealed the mono dispersed nature of Fe₃O₄@Au NPs with an average size of 20 nm which was confirmed using Dynamic light scattering (DLS) measurements. Zeta potential measurements along with UV–VIS spectroscopy demonstrated surface DOX loading on Fe₃O₄@Au NPs. Energy Dispersive X-ray Spectroscopy (EDX) assured the existence of both iron and gold elements in the prepared NPs. The paramagnetic properties of the prepared NPs were assessed by vibrating sample magnetometer (VSM). The maximum DOX-loading capacity was 100 μg DOX/mg of Fe₃O₄@Au NPs. It was found that DOX released more readily at acidic pH. In vitro studies on MCF-7 cell line elucidated that DOX loaded Fe₃O₄@Au NPs (Fe₃O₄@Au-PEG-DOX) have more potent therapeutic effect than free DOX. Knowledge gained in this study may open the door to pursue Fe₃O₄@Au NPs as a viable nanocarriers for different molecules delivery in many diagnostic and therapeutic applications.     

An investigation on the short-term biodegradability of chitosan with various molecular weights and degrees of deacetylation

Research efforts have been devoted to demonstrating that the pH-sensitive characteristics of poly NIPAAm/chitosan nanoparticles can be applied to targeting tumors. A copolymer of (NIPAAm) and chitosan (4:1, m/m) was synthesized, and its drug release characteristics investigated. The results revealed that drug-loaded nanoparticles which encapsulation and loading efficiencies were 85.7% and 9.6%, respectively, exhibited pH-sensitive responses to tumor pH. The cumulative release rate was significantly enhanced below pH 6.8 and decreased rapidly above pH 6.9 at 36.5 ± 0.5 °C. MTT assay and fluorescence microscopic study showed that drug release was drastically promoted in tumor surroundings while exerting less effect in normal conditions. For mice treated with nanoparticles, the decrease in body weight was limited, and significant tumor regression was observed with complete regression in more than 50% of the mice. The life span of tumor-bearing mice was significantly increased when they were treated with nanoparticles. Thereby, the super pH-sensitive poly NIPAAm/chitosan nanoparticles may provide outstanding advantages for anti-cancer drug delivery.     

In vivo delivery of small interfering RNA targeting brain capillary endothelial cells

Brain capillary endothelial cells (BCECs) play an important role in blood-brain barrier (BBB) functions and pathophysiologic mechanisms in brain ischemia and inflammation. We try to suppress gene expression in BCECs by intravenous application of small interfering RNA (siRNA). After injection of large dose siRNA with hydrodynamic technique to mouse, suppression of endogenous protein and the BBB function of BCECs was investigated. The brain-to-blood transport function of organic anion transporter 3 (OAT3) that expressed in BCECs was evaluated by Brain Efflux Index method in mouse. The siRNA could be delivered to BCECs and efficiently inhibited endogenously expressed protein of BCECs. The suppression effect of siRNA to OAT3 is enough to reduce the brain-to-blood transport of OAT3 substrate, benzylpenicillin at BBB. The in vivo siRNA-silencing method with hydrodynamic technique may be useful for the study of BBB function and gene therapy targeting BCECs.     

巨噬细胞膜伪装纳米颗粒的制备和功能表征

摘要 目的：巨噬细胞具有炎症趋化能力,近年来巨噬细胞膜伪装的纳米递送载体引起研究者的广泛关注。本文提供了一种巨噬细胞膜伪装纳米颗粒的方法,即摄取-挤出法,并对该法制得的纳米颗粒进行表征,考察纳米颗粒在不同细胞中的摄取。方法：利用溶胶-凝胶法制备装载阿霉素的介孔硅（DMSN）纳米颗粒,再利用RAW 264.7巨噬细胞吞噬DMSN,最后将巨噬细胞连续挤出制得巨噬细胞膜伪装的载有阿霉素的介孔硅（DMSN@CM）纳米颗粒。动态光散射激光粒度仪（DLS）测定DMSN@CM颗粒的粒径和表面电位,透射电子显微镜（TEM）观察纳米颗粒形态,聚丙烯酰胺凝胶电泳（SDS-PAGE）验证细胞膜的成功伪装。然后通过激光共聚焦显微镜与流式细胞术共同考察了DMSN@CM在不同细胞中的摄取情况。结果：成功制备了DMSN和DMSN@CM纳米颗粒。DMSN粒径为116.7±3.2 nm,zeta表面电势为 -29.5± 1.3 mV;MSN@CM粒径为128.0±9.3 nm,zeta表面电势为 -26.7 ±1.2 mV。TEM与SDS-PAGE共同验证了DMSN@CM表面细胞膜的成功包覆。细胞摄取试验表明巨噬细胞膜的伪装可以抑制RAW 264.7细胞对DMSN@CM的摄取;促进MDA-MB-231细胞对DMSN@CM的摄取。结论：利用摄取-挤出法成功构建了DMSN@CM纳米颗粒,该法简便高效,为纳米颗粒的细胞膜伪装提供了一种新的手段。     

Luminescent nanodiamonds for biomedical applications

In recent years, nanodiamonds have emerged from primarily an industrial and mechanical applications base, to potentially underpinning sophisticated new technologies in biomedical and quantum science. Nanodiamonds are relatively inexpensive, biocompatible, easy to surface functionalise and optically stable. This combination of physical properties are ideally suited to biological applications, including intracellular labelling and tracking, extracellular drug delivery and adsorptive detection of bioactive molecules. Here we describe some of the methods and challenges for processing nanodiamond materials, detection schemes and some of the leading applications currently under investigation.