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Abstract: In this paper, a simple approach was presented to prepare functional inorganic/organic composite microspheres in which the inorganic nanoparticles were encapsulated into the polyelectrolyte complexes between chitosan (CS) and poly(aspartic acid) sodium salt (PAsp). The magnetic microspheres were prepared via electrostatic interaction between the citrate groups stabilizing Fe3O4 nanoparticles and the amino groups of CS. Being taken as a kind of special polyelectrolyte with high molecular weight, the inorganic nanoparticles presented strong interaction with polyelectrolyte. By tuning the unit molar ratio of the opposite charged polyelectrolytes and the amount of Fe3O4 nanoparticles, the structure of the composite microspheres could be controlled and the dimension of microspheres ranged from 110 nm to 320 nm. Then the approach was extended to prepare luminescent-magnetic CS–PAsp microspheres by encapsulated Fe3O4 nanoparticles and CdTe quantum dots synchronously, which exhibited superior pH stability and remained strong photoluminescence properties after crosslinking. The CdTe–Fe3O4/CS–PAsp composite microspheres are potentially useful for further application in biolabeling and imaging. [Copyright &y& Elsevier]

Graphical abstract Biodegradable phosphorylcholine-based zwitterionic polymer nanogels with charge-conversion ability at tumor extracellular pH were fabricated by one-step reflux precipitation polymerization, leading to the enhanced tumor cellular uptake and controlled drug release. Abstract Zwitterionic polymer nanocarriers have attracted much attention in recent years due to their desirable biocompatibility and anti-fouling properties. However, the super-hydrophilic and neutral charge of zwitterionic polymer results in weak interactions with negatively charged cell membranes, which leads to suboptimal uptake by tumor cells. Herein, a series of biodegradable poly(2-methacryloyloxyethyl phosphorylcholine- s-s -vinylimidazole) (PMV) nanogels with uniform spherical shape was fabricated by one-step reflux precipitation polymerization, which was clean and efficient. The PMV nanogels remained in zwitterionic state at physiological pH (pH 7.4) and were converted rapidly to positive charged state at tumor extracellular pH (pH 6.5). Proton nuclear magnetic resonance spectra and acid-base titration experiment proved that the charge-conversion ability of PMV nanogels was attributed to protonation of the imidazole ring in an acidic environment. Protein stability experiment showed that PMV nanogels exhibited a protein-adsorption resistance at pH 7.4 for as long as 7 days while adsorbed protein rapidly at pH 6.5. Moreover, PMV nanogels showed a reducing-labile property, which was able to degrade into short linear polymer chains in the presence of reduction agents. Therefore, the doxorubicin (DOX) release profile was controlled finely with a low DOX leakage under physiological conditions (7.8% in 48 h) and a rapid DOX release in 10 mM glutathione at pH 7.4 (78.9% in 48 h). Confocal laser scanning microscope and flow cytometry showed that the PMV nanogels exhibit an enhanced cellular uptake by tumor cells at pH 6.5 compared with pH 7.4, which allows for a severe cytotoxic effect of DOX-loaded PMV nanogels against tumor cells. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monodisperse core–shell nanocomposites with fluorescent solid SiO2 core mesoporous silica shell. [•] DOX release study for F-nSiO2/mSiO2 with different shell thickness as carrier. [•] Smaller nanoparticles will be uptaken by HeLa cells easier. [ABSTRACT FROM AUTHOR]

Abstract: A general and facile strategy was developed to coat hydrophilic inorganic nanoparticles directly with mesoporous silica nanoparticles (MSNs). The cationic surfactant of cetyltrimethylammonium bromide (CTAB) was adsorbed to various negatively charged CdTe quantum dots, Fe3O4 nanocrystals or Au nanoparticles, introducing the bilayer of CTAB overcoating with positive charge. The subsequent sol–gel reaction of TEOS with the basic catalyst resulted in uniform nanocomposites. The concentration of CTAB and NH4OH in the recipe strongly influenced the number of inorganic nanoparticles in the nanocomposites and the homogeneity of MSNs shell. One dimensional Au nanorods and larger size of solid SiO2 nanoparticles were also able to coat with MSNs using a similar synthetic procedure. The proposed method was greatly simplified without the help of any mediators or silane coupling agents and excellent mesostructural performance was readily achieved. Compared to the methods known from the literatures for the coating of hydrophobic nanoparticles, this efficient way is especially useful for trapping different hydrophilic nanoparticles with arbitrary sizes and shapes into MSNs. These highly versatile multifunctional nanocomposites, together with the pH-responsible drug release behaviors, non-toxicity to normal cells and ease of uptake into cancer cells, are expected to be utilized as drug delivery system for simultaneous imaging and therapeutic applications. [Copyright &y& Elsevier]

Abstract: Submicron-size Fe3O4@silica core/shell microspheres were prepared by sol–gel method. Through coating inert silica shell and adjusting the thickness, the dispersibility of magnetic microspheres in water was greatly improved. The resultant Fe3O4@silica microspheres with controllable saturation magnetization between 34.3emu/g and 47.3emu/g were superparamagnetic. All as-prepared magnetic composite microspheres possessed fleetly magnetic responsivity. The PAA-modified Fe3O4@silica microspheres were used for selective adsorption and separation of lysozyme, and the experimental results showed that the maximum binding capacity is about 127mg/g. After surface modification of Fe3O4@silica with polyacrylic acid (PAA) flexible chains, the binding capacity of Fe3O4@silica-g-PAA microspheres for lysozyme were 22 times as much as that of pure Fe3O4@silica microspheres at the same pH condition. [Copyright &y& Elsevier]

Abstract: A novel luminescent nanocomposite assembly was prepared in aqueous solutions, via the electrostatic interaction between poly(ethylene glycol)-b-poly(-dimethylaminoethyl methacrylate) (PEG-b-PDMAEMA) double hydrophilic block copolymer (DHBC) and thioglycolic acid (TGA)-stabilized CdTe quantum dots (QDs). By tuning the molar ratios of QDs to DHBC, the nanocomposite assemblies could be well controlled and the dimension of these regular spherical QDs/PEG-b-PDMAEMA assemblies ranged from 40 to 75 nm in aqueous media. As the periphery of QDs/PEG-b-PDMAEMA nanocomposite assembly was composed of PEG segments when the PDMAEMA blocks and QDs were immobilized inside the assembly, the cytotoxicity of the assembly was significantly reduced, compared with that of pure PEG-b-PDMAEMA and QDs. The nanocomposite assembly also exhibited superior stability in salt solutions and remained strongly photoluminescent even when free radicals existed. Thus, the QDs/PEG-b-PDMAEMA nanocomposite assembly is potentially useful for a number of applications in biolabeling and imaging. [Copyright &y& Elsevier]