Surface modification of monodisperse magnetite nanoparticles for improved intracellular uptake to breast cancer cells

Nanoparticles have been widely used for a variety of biomedical applications and there is a growing need for highly specific and efficient uptake of the nanoparticles into target cells. Poly(ethylene glycol) (PEG), folic acid (FA), and their conjugate PEG-FA were attached to magnetite nanoparticles to compare their effects on the improvement of intracellular uptake of the nanoparticles to human breast cancer cells, BT-20. AFM and TEM results indicated that the nanoparticles after surface modification were monodisperse, with coatings on individual nanoparticles. The cell culture experiments showed that the PEG-FA coated nanoparticles were internalized into BT-20 cancer cells and exhibited higher efficiency of intracellular uptake than only PEG- or FA-coated nanoparticles. The surface modification protocols can also be used to modify the surfaces of other nanoparticles for targeting intracellular delivery.     

A chemical approach for cell-specific targeting of nanomaterials: small-molecule-initiated misfolding of nanoparticle corona proteins

A major challenge in nanomaterial science is to develop approaches that ensure that when administered in vivo, nanoparticles can be targeted to their requisite site of action. Herein we report the first approach that allows for cell-specific uptake of nanomaterials by a process involving reprogramming of the behavior of the ubiquitous protein corona of nanomaterials. Specifically, judicious surface modification of quantum dots with a small molecule that induces a protein-misfolding event in a component of the nanoparticle-associated protein corona renders the associated nanomaterials susceptible to cell-specific, receptor-mediated endocytosis. We see this chemical approach as a new and general method for exploiting the inescapable protein corona to target nanomaterials to specific cells.     

载药荧光纳米粒子的制备及在乳腺癌MCF-7细胞系的应用及效果评价

利用两亲性聚乙二醇-聚乳酸共聚物（PEG-PDLLA）包覆荧光染料（DPBA）和紫杉醇（PTX）,通过自组装方法制得载药荧光纳米粒子DPBA/PTX@PEG-PDLLA.纳米粒子尺寸均一,具有良好的生物相容性.对纳米粒子的发光性质、载药量和体外药物释放等进行了表征,并考察了纳米粒子对乳腺癌细胞MCF-7的抑制效果,观察了MCF-7细胞对纳米粒子的摄取情况.结果表明,DPBA/PTX@PEG-PDLLA纳米粒子具有较强的红光发射,不仅可以用于MCF-7肿瘤细胞质荧光成像,而且对肿瘤细胞的增殖具有一定的抑制能力.     

Effect of microemulsion variables on copper oxide nanoparticle uptake by AOT microemulsions

Ultradispersed metal oxide nanoparticles have applications as heterogeneous catalysts for organic reactions. Their catalytic activity depends primarily on their surface area, which in turn, is dictated by their size, colloidal concentration and stability. This work presents a microemulsion approach for in situ preparation of ultradispersed copper oxide nanoparticles and discusses the effect of different microemulsion variables on their stability and highest possible time-invariant colloidal concentration (nanoparticle uptake). In addition, a model which describes the effect of the relevant variables on the nanoparticle uptake is evaluated. The preparation technique involved solubilizing CuCl(2) in single microemulsions followed by direct addition of NaOH. Upon addition of NaOH, copper hydroxide nanoparticles stabilized in the water pools formed in addition to a bulk copper hydroxide precipitate at the bottom. The copper hydroxide nanoparticles transformed with time into copper oxide. After reaching a time-independent concentration, mixing had limited effect on the nanoparticle uptake and particle size. Particle size increased with increasing the surfactant concentration, concentration of the precursor salt, and water to surfactant mol ratio; while the nanoparticle uptake increased linearly with the surfactant concentration, displayed an optimum with R and a power function with the concentration of the precursor salt. Surface areas per gram of nanoparticles were much higher than literature values. Even though lower area per gram of nanoparticles was obtained at higher uptake, higher surface area per unit volume of the reverse micellar system was attained. A model based on water uptake by Wisor type II microemulsions, and previously used to describe iron oxide nanoparticle uptake by the same microemulsions, agreed well with the experimental results.     

Target-specific cellular uptake of PLGA nanoparticles coated with poly(L-lysine)-poly(ethylene glycol)-folate conjugate

Poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles with anionic surface charge were surface coated with cationic di-block copolymer, poly(L-lysine)-poly(ethylene glycol)-folate (PLL-PEG-FOL) conjugate, for enhancing their site-specific intracellular delivery against folate receptor overexpressing cancer cells. The PLGA nanoparticles coated with the conjugate were characterized in terms of size, surface charge, and change in surface composition by XPS. By employing the flow cytometry method and confocal image analysis, the extent of cellular uptake was comparatively evaluated under various conditions. PLL-PEG-FOL coated PLGA nanoparticles demonstrated far greater extent of cellular uptake to KB cells, suggesting that they were mainly taken up by folate receptor-mediated endocytosis. The enhanced cellular uptake was also observed even in the presence of serum proteins, possibly due to the densely seeded PEG chains. The PLL-PEG-FOL coated PLGA nanoparticles could be potentially applied for cancer cell targeted delivery of various therapeutic agents.     

Stable aqueous ZnO@polymer core-shell nanoparticles with tunable photoluminescence and their application in cell imaging

Stable aqueous solutions of ZnO@polymer core-shell nanoparticles with tunable photoluminescence are prepared through a simple sol-gel route. The copolymer shell has many hydrophilic external groups and a hydrophobic internal layer which connects ZnO cores through covalent bonds. The optimal samples show quantum yield above 50% and stable emission for months. These samples with their concentrations of below 0.2 mg/mL are nontoxic to human cells. After uptake of these ZnO@polymer nanoparticles, the luminescent cells have enough life under UV light for microscopic imaging.     

Self‐Assembled Fluorescent Organic Nanoparticles for Live‐Cell Imaging

Fluorescent, cell‐permeable, organic nanoparticles based on self‐assembled π‐conjugated oligomers with high absorption cross‐sections and high quantum yields have been developed. The nanoparticles are generated with a tuneable density of amino groups for charge‐mediated cellular uptake by a straightforward self‐assembly protocol, which allows for control over size and toxicity. The results show that a single amino group per ten oligomers is sufficient to achieve cellular uptake. The non‐toxic nanoparticles are suitable for both one‐ and two‐photon cellular imaging and flow cytometry, and undergo very efficient cellular uptake.     

Synthesis of surface-modified quantum dots

The review discusses the main methods used to obtain surface-modified quantum dots, specifically silicon, heavy metal chalcogenide and pnictide semiconductor nanoparticles. Examples of transformation processes of the grafted layer are considered. The importance of surface modification of A^IIB^VI- and A^IIIB^V-type semiconductor nanoparticles for the practical application of quantum dots is shown. It was determined that the most promising areas of their practical application are biology, medicine, and pharmacology. Special attention is paid to the hydrophilization of quantum dots, because only these materials can be used in biomedical applications. Modification of the quantum dot surface with amino acids is considered.

     

聚合物纳米粒子的结构和性能对胞吞和细胞功能的影响

随着纳米医学的发展,越来越多的聚合物纳米粒子被用作荧光探针和药物或基因的载体,在生物分析、检测以及药物传输和基因治疗等领域得到应用。细胞的胞吞是细胞将细胞外基质、病毒、微组织或纳米粒子运送到细胞内部的一个重要生理过程。研究细胞对纳米粒子的胞吞,有助于从细胞层次上理解生命现象,掌握细胞内治疗的机理。本文综述了近几年来细胞和聚合物纳米粒子之间相互作用的最新研究结果。首先介绍了用于胞吞研究的常用聚合物纳米粒子体系及其功能化方法,尤其是荧光探针的复合与表面修饰。进而介绍了细胞和聚合物纳米粒子之间相互作用的基本过程,包括聚合物纳米粒子在细胞转运过程中的驱动力、细胞内转运过程、在细胞中的分布及其细胞毒性。对影响聚合物纳米微粒胞吞的因素如纳米粒子浓度、共培养时间、纳米粒子性能（形状、粒径、电荷和PEG修饰）、细胞类型和培养条件等进行了总结。最后重点介绍了用于受体介导细胞胞吞的聚合物纳米粒子体系,指出了目前研究工作中的不足及未来发展方向。     

Optical properties of Ag/CdTe nanocomposite self-organized by electrostatic interaction

Ag/CdTe nanocomposite was prepared via self-organization process by electrostatic interaction between positively charged CdTe quantum dots and negatively charged Ag nanoparticles and examined with respect to their optical properties. The positively charged CdTe quantum dots and negatively charged Ag nanoparticles were synthesized separately by modifying nanoparticles surface with cationic and anionic thiol compounds, respectively. The result showed that the mixing ratio of Ag nanoparticles to CdTe quantum dots is an important parameter for controlling resulting composites. The resulting solution is optically transparent if one component is in excess. Photoluminescence of CdTe quantum dots undergoes considerably quenching if CdTe nanocrystals are in excess and SERS spectra of BVPP absorbed on Ag colloid became stronger if Ag nanoparticles are in excess. Nevertheless, while the ratio is approximately 1, micrometer-sized solid composite is obtained with the elapse of 1h after mixing. SERS spectra for solid composite only exhibit the signals of the CdS nanocrystal which reflected that prolonged refluxing during the synthesis leads to a partial hydrolysis of the thiols and to the incorporation of the sulfur from the thiol molecules into the the growing nanoparticles to form mixed CdTe(S) nanocrystal, similar to CdTe/CdS core/shell structure. From the results, we conclude that optical properties of Ag/CdTe are dependent on the mixing ratio of both nanoparticles.     

A biophysical perspective of understanding nanoparticles at large

In this article we present a biophysical perspective that describes the fate of nanoparticles in both the aqueous phase and in living systems. Specifically, we show the correlations between the physicochemistry of fullerenes and their uptake, translocation, transformation, transport, and biodistribution in mammalian and plant systems, at the molecular, cellular, and whole organism level. In addition to fullerenes and their structural derivatives, we describe the biological and environmental implications and applications of the condensed matter of carbon nanotubes and quantum dots, and the soft condensed matter of plastic and dendrimers. The main purpose of this article is to demonstrate the vast opportunities and unique advantages of applying experimental and simulation biophysics to the nascent research field of understanding nanoparticles at large.     

Synthesis and characterization of multifunctional Fe3O4/poly(fluorescein O-methacrylate) core/shell nanoparticles

Multifunctional fluorescent and superparamagnetic Fe(3)O(4)/poly(fluorescein O-methacrylate) [Fe(3)O(4)/poly(FMA)] nanoparticles with core/shell structure were synthesized via surface-initiated polymerization. First, polymerizable double bonds were introduced onto the surface of Fe(3)O(4) nanoparticles via ligand exchange and a condensation reaction. A fluorescent monomer, FMA, was then polymerized to the double bonds at the surface via free-radical polymerization, leading to form a fluorescent polymer shell around the superparamagnetic Fe(3)O(4) core. The resultant Fe(3)O(4)/poly(FMA) nanoparticles were characterized by Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy to confirm the reactions. Transmission electron microscopy images showed that the Fe(3)O(4)/poly(FMA) nanoparticles have a spherical and monodisperse core/shell morphology. Photoluminescence spectroscopy and superconducting quantum interference device magnetometer analyses confirmed that the Fe(3)O(4)/poly(FMA) nanoparticles exhibited fluorescent and superparamagnetic properties, respectively. In addition, we demonstrated the potential bioimaging application of the Fe(3)O(4)/poly(FMA) nanoparticles by visualizing the cellular uptake of the nanoparticles into A549 lung cancer cells.     

Photochemically and electrochemically triggered Au nanoparticles "sponges"

Stimuli-triggered wettability of surfaces and controlled uptake and release of substrates by "smart" materials are essential for drug delivery and microfluidic control. A composite "sponge" consisting of bis-aniline-bridged Au nanoparticles (NPs), functionalized with photoisomerizable nitrospiropyran/nitromerocyanine that includes selective imprinted molecular recognition sites for N,N'-bis(3-sulfonatopropyl)-4,4'-bipyridinium (PVS) was electropolymerized on a Au electrode. The system is triggered by photonic and/or electrical signals to yield four different states exhibiting variable binding/release capacities for PVS and controlled wettability of the surface. The electrical/optical uptake and release of PVS to and from the Au NPs "sponge", respectively, is followed by CdSe/ZnS quantum dots, acting as an auxiliary photonic label.     

Electrochemical detection of quantum dots by stabilization of electrogenerated copper species

The determination of quantum dots is of particular interest as they are frequently used as labels in electrochemical biosensors. In this paper, we describe a method for the detection of very low concentrations of quantum dots using the voltammetric response of copper in ammonia solution. Copper species electrogenerated on the electrode surface are stabilized by the nanoparticles, preventing their oxidation by dissolved oxygen, and a relationship between the concentration of the nanoparticles and the copper voltammetric response can thus be obtained. The reported method shows a linear range between 0.05 and 2 nM of quantum dots, with a limit of detection in the order of 9 × 10⁷ nanoparticles. This method could be employed to improve the detection limit of electrochemical biosensors using quantum dots as labels.     

Multiplexed screening of cellular uptake of gold nanoparticles using laser desorption/ionization mass spectrometry

Gold nanoparticles (AuNPs) are highly promising candidates as drug delivery agents into cells of interest. We describe for the first time the multiplexed analysis of nanoparticle uptake by cells using mass spectrometry. We demonstrate that the cellular uptake of functionalized gold nanoparticles with cationic or neutral surface ligands can be readily determined using laser desorption/ionization mass spectrometry of cell lysates. The surface ligands have "mass barcodes" that allow different nanoparticles to be simultaneously identified and quantified at levels as low as 30 pmol. Using this method, we find that subtle changes to AuNP surface functionalities can lead to measurable changes in cellular uptake propensities.     

Nanocarriers for cytoplasmic delivery: cellular uptake and intracellular fate of chitosan and hyaluronic acid-coated chitosan nanoparticles in a phagocytic cell model

The cellular uptake of hyaluronic-acid-coated, negatively charged chitosan/triphosphate nanoparticles and that of uncoated, positively charged ones is investigated by studying cellular localization, uptake kinetics and mechanism of internalization in J774.2 macrophages, using non-phagocytic L929 fibroblasts as a control for uncoated nanoparticles. Both kinds of nanoparticles undergo endosomal escape and adopt a similar clathrin-based endocytic mechanism. The surface decoration with HA profoundly influences the kinetics of cellular uptake, with an at least two orders of magnitude slower kinetics, but also the nature of the binding on the cellular surface.     

Host-guest sensing by calixarenes on the surfaces

The present critical review reports on recent developments of optical nanoparticles based on the association of gold, silver, silica and quantum dots and calixarenes. These hybrid organic-inorganic compounds characterized by a thick organic layer self-assembled on the surface of a core of mineral surface atoms take advantage of the supramolecular recognition of luminescent calixarenes to fabricate nanodevices of nanoparticle size, capable of detecting metal cations, polyaromatic hydrocarbons and pesticides. Also presented is an explanation of the involvement of such nanoparticles in biochemical systems. This critical review provides an overview of their preparation, the manner in which they are characterized, and their use (108 references).     

Experimental study and modelling of effective parameters on removal of Cd(II) from water by halloysite/graphene quantum dots magnetic nanocomposite as an adsorbent using response surface methodology

Graphene quantum dots (GQDs) were covalently immobilized onto the NiFe₂O₄-halloysite nanotubes (NiFe₂O₄-HNTs) surface to fabricate a nanocomposite material utilized as an active adsorbent to eliminate Cd(II) ions from water. NiFe₂O₄ nanoparticles were synthesized and simultaneously deposited on HNTs. Then, the material surface was coated by APTES (aminopropyltriethoxysilane) to cause GQDs be connected to the external layer via an amide bond. The prepared nanomaterial structure was identified by TEM, XRD, FT-IR, BET isotherm, EDS analysis and VSM (vibrating sample magnetometry). Box–Behnken design incorporated with response surface method (RSM) was utilized to find out the impact of pH, time, initial concentration of Cd(II) and adsorbent dose on cadmium removal. Study discovered that adsorption operation is the quasi-second-order kinetic model and adapted more precisely with Langmuir adsorption model. The Langmuir highest uptake capacity of 34.72 mg/g at 298 K was acquired. The Elovich model recommended that the process is a kind of chemisorption. The calculated thermodynamic variables verified that the uptake process is endothermic and spontaneous. Additionally, the adsorbent can be simply separated with the aid of a magnet. In this study, we have suggested a practical method for the synthesis of the NiFe₂O₄/halloysite nanotubes/graphene quantum dots magnetic nanoparticles for cadmium removal from water.     

Aqueous ferrofluid of magnetite nanoparticles: Fluorescence labeling and magnetophoretic control

A method is presented for the preparation of a biocompatible ferrofluid containing dye-functionalized magnetite nanoparticles that can serve as fluorescent markers. This method entails the surface functionalization of magnetite nanoparticles using citric acid to produce a stable aqueous dispersion and the subsequent binding of fluorescent dyes to the surface of the particles. Several ferrofluid samples were prepared and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis, transmission electron microscopy (TEM), and SQUID magnetometry. In addition, confocal fluorescence microscopy was used to study the response of the fluorescent nanoparticles to an applied magnetic field and their uptake by cells in vitro. Results are presented on the distribution of particle sizes, the fluorescent and magnetic properties of the nanoparticles, and the nature of their surface bonds. Biocompatible ferrofluids with fluorescent nanoparticles enable optical tracking of basic processes at the cellular level combined with magnetophoretic manipulation and should be of substantial value to researchers engaged in both fundamental and applied biomedical research.     

ZnO纳米粒子结构对光电量子限域特性的影响

Zn O作为一种宽禁带 (3 .3 6e V)高激子结合能 (60 me V)的半导体材料已引起人们的关注 .Zn O纳米粒子的比表面积较大 ,表面活性较高 ,对周围环境敏感 ,使其成为传感器制作中最有前途的材料[1] ,还在太阳能转换[2 ] 、发光材料[3] 、半导体表面修饰与敏化[4 ] 、纳米电子学以及分子电子学器件[5] 等领域显示出广阔的应用前景 .制约这些应用的关键是 Zn O纳米粒子表面和界面的电子结构和电荷转移行为 ,但有关此方面的报道较少 .本文用溶胶 -凝胶法制备了不同粒径的 Zn O纳米粒子 ,应用表面光电压谱 (SPS)和场诱导表面光电压谱 (FISPS…