A novel platform for enhanced biosensing based on the synergy effects of electrospun polymer nanofibers and graphene oxides.

A novel biosensing platform was developed by combining the advantages of electrospun poly(vinyl alcohol) (PVA)/chitosan nanofibers and graphene oxides (GO). Glucose oxidase (GOD) was employed as a model enzyme. By co-electrospinning the solution of PVA, chitosan, GOD and GO, the PVA/chitosan/GOD/GO nanofibers were directly modified on the platinum (Pt) electrode. The UV-vis spectra and the FTIR spectra were used to characterize the GO nanosheets. The morphologies of fabricated electrospun nanofibers were characterized by high resolution scanning electron microscopy. After a thin layer of nafion was modified on the surface of matrix, the as-prepared electrode was used to detect glucose. The electrode exhibited great advantages in high sensitivity, low detection limit and wide linear range. In the meantime, the electrode showed good stability, acceptable reproducibility, and excellent anti-interference capability for ascorbic acid, uric acid, lactose and sucrose. Moreover, the novel biosensor was successfully applied for the glucose determination in human serum samples. The mechanism of efficient biosensing of the nafion/PVA/chitosan/GOD/GO/Pt electrode was analyzed in detail and the results show that it can be due to the synergy effects of electrospun nanofibers and GO nanosheets.

A study of the electron transfer and photothermal effect of gold nanorods on a glucose biosensor.

A new glucose biosensor based on the electron transfer and photothermal effect of gold nanorods (GNRs) is reported here. The biosensor was prepared by immobilizing glucose oxidase (GOx) on a platinum (Pt) electrode by a composite film consisting of GNRs, polyvinyl butyral (PVB) and glutaraldehyde. GNRs were synthesized by a gold seed-mediated cetyltrimethylammonium bromide (CTAB) surfactant-assisted approach. The fabrication, characterization and analytical performance of the glucose biosensor based on GNRs are described in this paper. Moreover, the modulation of the biosensor by the photothermal effect based on the unique surface plasma resonance (SPR) property of GNRs was investigated for the first time. The results show that the current response of a glucose biosensor can significantly increase, induced by the electrical conductivity and photothermal effect of GNRs.

Controlled drug delivery system based on magnetic hollow spheres/polyelectrolyte multilayer core-shell structure.

A novel controlled drug delivery system was fabricated by coating chitosan/PAA multilayer onto magnetic hollow spheres via a "Layer-by-Layer" (LBL) assembly approach. Cefradine was used as a model drug to evaluate the drug release characteristics of this core-shell hollow structure and the results show that it exhibits a sustained release of the drug and the release rate can be regulated by the pH environment of release medium. It is believed that this core-shell hollow structure, which combines the advantage of controlled delivery as well as magnetic targeting, has commendable potential in drug delivery therapeutics.

Shape matters when engineering mesoporous silica-based nanomedicines.

Mesoporous silica nanomaterials have been successfully employed in the development of novel carriers for drug delivery. Numerous studies have been reported on engineering mesoporous silica-based carriers for drug loading, release, cellular uptake, and biocompatibility. A number of design parameters that govern the in vitro and in vivo performance of the carriers, including particle diameter, surface chemistry, and pore size, have been tuned to optimize nanomedicine efficacy. However, particle shape, which may generate a high impact on nanomedicine performance, has still not been thoroughly investigated. This is probably due to the limited availability of strategies and techniques to produce non-spherical mesoporous silica nanomaterials. Recent breakthroughs in controlling the particle shape of mesoporous silica nanomaterials have confirmed the important roles of shape on nanomedicine development. This review article introduces various fabrication methods for non-spherical mesoporous silica nanomaterials, including rod, ellipsoid, film, platelet/sheet, and cube, and the roles of particle shape in nanomedicine applications.

Using silver nanoparticle to enhance current response of biosensor.

In this paper, we present a simple procedure to increase the sensitivity of a glucose biosensor. The feasibility of an amperometric glucose biosensor based on immobilization of glucose oxidase (GOx) in silver (Ag) sol was investigated for the first time. GOx was simply mixed with Ag nanoparticles and cross-linked with a polyvinyl butyral (PVB) medium by glutaraldehyde. Then a platinum electrode was coated with the mixed solution. The effects of the amount of the Ag particles used, with respect to the current response for enzyme electrodes, were studied. A set of experimental results indicate that the current response for the enzyme electrode containing hydrophobic Ag sol increased from 0.531 to 31.17 microA in the solution of 10 mmol/L beta-D glucose. The time reaching the steady-state current response reduced from 60 to 20s, three times less than those without Ag particles involved.

One-pot synthesis of active copper-containing carbon dots with laccase-like activities.

Herein, an effective strategy for designing a new type of nanozyme, blue fluorescent laccase mimics, is reported. Active copper-containing carbon dots (Cu-CDs) were synthesized through a simple, nontoxic and one-pot hydrothermal method, which showed favorable photoluminescence properties and good photostability under high-salt conditions or in a broad pH range (3.0-13.5). The Cu-CDs possessed intrinsic laccase-like activities and could catalyze the oxidation of the laccase substrate p-phenylenediamine (PPD) to produce a typical color change from colorless to brown. Poly(methacrylic acid sodium salt) (PMAA) not only was used as the carbon source and reducing agent, but also provided carboxyl groups to assist flocculation between Cu-CDs and polyacrylamide, which facilitated the removal of PPD. Importantly, the intrinsic fluorescence of the as-prepared Cu-CDs could indicate the presence of hydroquinone, one of the substrates of laccases, based on laccase mimics and fluorescence quenching.

Gelatin microcapsules for enhanced microwave tumor hyperthermia.

Local and rapid heating by microwave (MW) irradiation is important in the clinical treatment of tumors using hyperthermia. We report here a new thermo-seed technique for the highly efficient MW irradiation ablation of tumors in vivo based on gelatin microcapsules. We achieved 100% tumor elimination in a mouse model at an ultralow power of 1.8 W without any side-effects. The results of MTT assays, a hemolysis test and the histological staining of organs indicated that the gelatin microcapsules showed excellent compatibility with the physiological environment. A possible mechanism is proposed for MW hyperthermia using gelatin microcapsules. We also used gelatin microcapsules capped with CdTe quantum dots for in vivo optical imaging. Our study suggests that these microcapsules may have potential applications in imaging-guided cancer treatment.

Shape-mediated biological effects of mesoporous silica nanoparticles.

For biomedical applications, mesoporous silica nanoparticles (MSNs)-based theranostic agents have shown to be a promising alternative. Rational design of particulate systems should consider, beside the physicochemical properties of particle size and surface chemistry, shape features as aspect ratio (AR) and morphology. Recent advances of fabrication technologies for manufacturing different shaped MSNs and evaluation means of its in vitro and in vivo biological performance provide new aspects and wisdom in nanomedicine development. In this review, we discussed the recent progress in the preparation of different shaped MSNs and the evaluation of shape-mediated biological effects. Firstly, we provide an overview of preparation strategies for fabricating MSNs with different aspect ratios and different morphologies, including hollow/rattle MSNs, multishell MSNs, and mesoporous silica nanocomposites. We then highlight the aspect ratio- and morphology-mediated biological effects of MSNs respectively. For AR-mediated biological effects of MSNs, we put our focus in the particle ARs effect on cellular uptake, biocompatibility, and drug delivery. For morphology-mediated biological effects of MSNs, we emphasize on how particle shapes could affect tumor therapy. Finally, for application considerations, we conclude with our personal perspectives on the directions in which future studies in this field might be placed.

A new amperometric glucose biosensor based on one-step electrospun poly(vinyl alcohol)/chitosan nanofibers.

In this work, a new glucose amperometric biosensor was developed by directly electrospinning poly(vinyl alcohol)/chitostan nanofibers on the surface of the platinum electrode, in which glucose oxidase (GOD) was effectively immobilized in nanofibers by encapsulation. After been cross-linked in glutaraldehyde vapor and modified with a thin nafion film, the nanofibers (PVA/chitosan/GOD)/nafion electrode was used for glucose amperometric measurements. The electrospun nanofibrous enzyme membrane served as a better sensing element than the casing one due to the unique properties of nanofibers such as the special three-dimensional network structure, large pores, high porosity, and large surface to volume ratios. The as-prepared biosensor showed a wide linear calibration range, low detection limit, and low apparent Michaelis-Menten constant in the glucose determination. The stability, reproducibility and anti-interference capability of biosensor were also presented. Furthermore, the new biosensor was successfully applied to detect glucose in human serum samples.

Impact of PEGylation on the biological effects and light heat conversion efficiency of gold nanoshells on silica nanorattles.

As an excellent photothermal agent candidate, gold nanoshells have attracted a great deal of attention, but the influences of PEGylation on their biological effects and light heat conversion efficiency remain unclear. Here we investigate the influences of PEGylation density on the gold nanoshells on silica nanorattles (GSNPs) to their biological effects, including their cellular uptake, "corona" of biological macromolecules they are covered with, in vivo biodistribution and toxicities, and their in vitro and in vivo light heat conversion efficiency. The results suggest PEGylation obviously impacts the uptake patterns of GSNPs. Less-density PEGylated GSNPs show enhanced cellular uptake caused by the high dose exposure on cell surface due to their rapid aggregation. High-density PEGylated GSNPs show advantages in less toxicity for suppression of aggregation of GSNPs, avoidance of RES, good enhanced permeability and retention (EPR) effect of cancerous tumors, especially the enhanced light heat conversion efficiency in vivo. Less or insufficient PEGylation may induce in vivo toxicity. This study highlights the need to study the effect of PEGylation for near infrared (NIR) light absorbing nanoparticles to predict the effects and safety of nanotherapeutics.

Multifunctional Fe3O4@P(St/MAA)@chitosan@Au core/shell nanoparticles for dual imaging and photothermal therapy.

Merging different components into a single nanoparticle can exhibit profound impact on various biomedical applications including diagnostics, imaging, and therapy. However, retaining the unique properties of each component after integration has proven to be a significant challenge. Our previous research demonstrated that gold nanoshells on polystyrene spheres have potential in photohermal therapy. Here, we report a facile and green strategy to synthesize a multifunctional nanocomposite with Fe3O4 core coated gold nanoshells as dual imaging probes and photothermal agents. The as-prepared nanoparticles exhibit well-defined structure and excellent physical properties such as magnetic and plasmonic activities. Therefore, they were applied as contrast agents in magnetic resonance imaging (MRI) and dark field imaging (DFI). Besides, we demonstrated their potential application in photothermal therapy. Moreover, the obtained multifunctional nanoparticles have shown excellent biocompatibility for their low cytotoxicity and hemolyticity.

Highly H2O2-sensitive electrospun quantum dots nanocomposite films for fluorescent biosensor.

Bright CdSe quantum dots (QDs)/polycaprolactone (PCL) nanocomposite fluorescent films were fabricated by electronspinning. By using chloroform and N,N-dimethylformamide as electronspinning solvent, the oil-soluble CdSe QDs were uniformly distributed in PCL fibers, and were directly employed as optical probe without any modification processing. The fluorescences of CdSe QDs/PCL nanocomposite films were quickly quenched when the films were contacted with H2O2, solution. In the presence of glucose oxidase (GOD), the fluorescence intensities of these fluorescent films exhibit a liner change with the concentrations of glucose. The H2O2-sensitive electrospun QDs nanocomposite films are highly uniform and repeatable, demonstrating the potential to fabricate stable, sensitive and recyclable fluorescent biosensor for the detection different H2O2-generating oxidases and their substrates.

Mesoporous silica nanoparticles: synthesis, biocompatibility and drug delivery.

In the past decade, mesoporous silica nanoparticles (MSNs) have attracted more and more attention for their potential biomedical applications. With their tailored mesoporous structure and high surface area, MSNs as drug delivery systems (DDSs) show significant advantages over traditional drug nanocarriers. In this review, we overview the recent progress in the synthesis of MSNs for drug delivery applications. First, we provide an overview of synthesis strategies for fabricating ordered MSNs and hollow/rattle-type MSNs. Then, the in vitro and in vivo biocompatibility and biotranslocation of MSNs are discussed in relation to their chemophysical properties including particle size, surface properties, shape, and structure. The review also highlights the significant achievements in drug delivery using mesoporous silica nanoparticles and their multifunctional counterparts as drug carriers. In particular, the biological barriers for nano-based targeted cancer therapy and MSN-based targeting strategies are discussed. We conclude with our personal perspectives on the directions in which future work in this field might be focused.

Synthesis of fluorescent Ag nanoclusters and their application in α-L-fucosidase detection.

Highly fluorescent Ag nanoclusters (NCs) were successfully prepared by a simple and nontoxic approach, and the as-prepared Ag NCs could be utilized for the AFu detection with a lower detection limit of 0.001 U L(-1).

Size dependent cellular uptake, in vivo fate and light-heat conversion efficiency of gold nanoshells on silica nanorattles.

Despite advances in photothermal therapy of gold nanoshells, reliable evaluations of their size dependence on the relative biological effects are needed. We report the size effects of PEGylated gold nanoshells on silica nanorattles (pGSNs) on their cellular uptake, in vivo fate and light-heat conversion efficiency in this study. The results indicate that smaller pGSNs have enhanced cellular uptake by the MCF-7 cells. For in vivo biodistribution study, pGSNs of different particle sizes (84-315 nm) distribute mainly in the liver and spleen in MCF-7 tumor-bearing BALB/c nude mice. Smaller pGSNs have a longer blood-circulation lifetime and higher light-heat conversion efficiency both in vitro and in vivo compared with larger ones. All three sizes of pGSNs can be excreted from the mice body at a slow rate and do not cause tissue toxicity after intravenous injection at a dosage of 20 mg kg(-1) for three times. The data support the feasibility of optimizing the therapeutic process for photothermal cell killing by plasmonic gold nanoshells.

Doxorubicin loaded silica nanorattles actively seek tumors with improved anti-tumor effects.

Silica nanorattles (SNs) have proven to be promising vehicles for drug delivery. In order to further enhance efficacy and minimize adverse effects, active targeted delivery to tumors is necessary. In this work, SNs modified with a tumor specific targeting ligand, folic acid (FA), was used as carrier of doxorubicin (DOX) (DOX-FA-SNs). Drug loading, cytotoxicity and cellular uptake of DOX-FA-SNs in vitro in human cervical carcinoma cells (HeLa cells) were evaluated. DOX-FA-SNs showed a higher cytotoxicity in human cervical carcinoma cells (HeLa cells) than DOX loaded carboxyl (-COOH) and poly(ethylene glycol) (PEG) modified SNs (DOX-COOH-SNs and DOX-PEG-SNs, respectively). However, DOX-FA-SNs showed lower cytotoxicity in folate receptor negative normal mouse fibroblast cells (L929 cells) compared with free DOX. In vivo tumor-targeted fluorescence imaging indicated specific tumor targeting and uptake of FA-SNs in nude mice bearing subcutaneous HeLa cell-derived xenograft tumors. In vivo anti-tumor experiments demonstrated that DOX-FA-SNs (10 mg kg(-1) of DOX) significantly regressed the tumor growth and reduced toxicity compared with free DOX. These results have great significance in developing and optimizing SNs as effective intracellular delivery and specific tumor targeting vehicles.

Co-encapsulation of magnetic Fe3O4 nanoparticles and doxorubicin into biodegradable PLGA nanocarriers for intratumoral drug delivery.

In this study, the authors constructed a novel PLGA [poly(D,L-lactic-co-glycolic acid)]-based polymeric nanocarrier co-encapsulated with doxorubicin (DOX) and magnetic Fe(3)O(4) nanoparticles (MNPs) using a single emulsion evaporation method. The DOX-MNPs showed high entrapment efficiency, and they supported a sustained and steady release of DOX. Moreover, the drug release was pH sensitive, with a faster release rate in an acidic environment than in a neutral environment. In vitro, the DOX-MNPs were easily internalized into murine Lewis lung carcinoma cells and they induced apoptosis. In vivo, the DOX-MNPs showed higher antitumor activity than free DOX solution. Furthermore, the antitumor activity of the DOX-MNPs was higher with than without an external magnetic field; they were also associated with smaller tumor volume and a lower metastases incidence rate. This work may provide a new modality for developing an effective drug delivery system.

The shape effect of mesoporous silica nanoparticles on biodistribution, clearance, and biocompatibility in vivo.

In our previous study we reported that the interaction of nanoparticles with cells can be influenced by particle shape, but until now the effect of particle shape on in vivo behavior remained poorly understood. In the present study, we control the fabrication of fluorescent mesoporous silica nanoparticles (MSNs) by varying the concentration of reaction reagents especially to design a series of shapes. Two different shaped fluorescent MSNs (aspect ratios, 1.5, 5) were specially designed, and the effects of particle shape on biodistribution, clearance and biocompatibility in vivo were investigated. Organ distributions show that intravenously administrated MSNs are mainly present in the liver, spleen and lung (>80%) and there is obvious particle shape effects on in vivo behaviors. Short-rod MSNs are easily trapped in the liver, while long-rod MSNs distribute in the spleen. MSNs with both aspect ratios have a higher content in the lung after PEG modification. We also found MSNs are mainly excreted by urine and feces, and the clearance rate of MSNs is primarily dependent on the particle shape, where short-rod MSNs have a more rapid clearance rate than long-rod MSNs in both excretion routes. Hematology, serum biochemistry, and histopathology results indicate that MSNs would not cause significant toxicity in vivo, but there is potential induction of biliary excretion and glomerular filtration dysfunction. These findings may provide useful information for the design of nanoscale delivery systems and the environmental fate of nanoparticles.

The effect of the shape of mesoporous silica nanoparticles on cellular uptake and cell function.

The interaction between nanoparticles (NPs) and cells has been studied extensively, but the effect of particle shape on cell behavior has received little attention. Herein three different shaped monodisperse mesoporous silica nanoparticles (MSNs) of similar particle diameter, chemical composition and surface charge but with different aspect ratios (ARs, 1, 2, 4) were specially designed. Then the effects of particle shape of these three different shaped particles on cellular uptake and behavior were studied. The results indicated that these different shaped particles were readily internalized in A375 human melanoma (A375) cells by nonspecific cellular uptake. Particles with larger ARs were taken up in larger amounts and had faster internalization rates. Likewise, it was also found that particles with larger ARs had a greater impact on different aspects of cellular function including cell proliferation, apoptosis, cytoskeleton formation, adhesion and migration. These results show that nanoparticles should no longer be viewed as simple carriers for biomedical applications, but can also play an active role in mediating biological effects. Therefore, our findings may provide useful information for the development of new strategies for the design of efficient drug delivery nanocarriers and therapeutic systems and provide insights into nanotoxicity.

A practical glucose biosensor based on Fe(3)O(4) nanoparticles and chitosan/nafion composite film.

A practical glucose biosensor was developed by combining the intrinsic peroxidase-like activity of Fe(3)O(4) nanoparticles (Fe(3)O(4) NPs) and the anti-interference ability of the nafion film. Glucose oxidase (GOD) was simply mixed with Fe(3)O(4) NPs and cross-linked on the Pt electrode with chitosan (Cs) medium by glutaraldehyde, and then covered with a thin nafion film. The biosensor showed high sensitivity (11.54 microAcm(-2)mM(-1)), low detection limit (6 x10(-6)M), and good storage stability. A linear calibration plot was obtained in the wide concentration range from 6 x10(-6) to 2.2 x10(-3)M. The modified electrode could virtually eliminate the interference during the detection of glucose. Furthermore, the biosensor was successfully applied to detect glucose in human serum sample. This fabrication of glucose biosensor was of considerable interest due to its promise for simple procedure and optimizing conditions in practical application.