Search

Purpose: The objective of this study is to investigate cellular uptake of prodrug-loaded nanoparticle (NP). Another objective is to study bioconversion of stereoisomeric dipeptide prodrugs of ganciclovir (GCV) including L-Val-L-Val-GCV (LLGCV), L-Val-D-Val-GCV (LDGCV) andd-Val-l-Val-GCV (DLGCV) in human corneal epithelial cell (HCEC) model. Methods: Poly(D,L-lactic-co-glycolic acid) (PLGA) NP encapsulating prodrugs of GCV were formulated under a double emulsion method. Fluorescein isothiocyanate isomer–PLGA conjugates were synthesized to fabricate biocompatible fluorescent PLGA NP. Intracellular uptake of FITC-labeled NP was visualized by a fluorescent microscope in HCEC cells. Results: Fluorescent PLGA NP and non-fluorescent NP display similar hydrodynamic diameter in the range of 115–145 nm with a narrow particle size distribution and zeta potentials around −13 mV. Both NP types showed identical intracellular accumulation in HCEC cells. Maximum uptake (around 60%) was noted at 3 h for NP. Cellular uptake and intracellular accumulation of prodrugs are significantly different among three stereoisomeric dipeptide prodrugs. The microscopic images show that NPs are avidly internalized by HCEC cells and distributed throughout the cytoplasm instead of being localized on the cell surface. Following cellular uptake, prodrugs released from NP gradually bioreversed into parent drug GCV. LLGCV showed the highest degradation rate, followed by LDGCV and DLGCV. Conclusion: LLGCV, LDGCV and DLGCV released from NP exhibited superior uptake and bioreversion in corneal cells. [ABSTRACT FROM AUTHOR]

Poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles (NP) of Val-Val dipeptide monoester prodrugs of ganciclovir (GCV) including L-Val-L-Val-GCV (LLGCV), L-Val-D-Val-GCV (LDGCV) and D-Val-L-Val-GCV (DLGCV) were formulated and dispersed in thermosensitive PLGA-PEG-PLGA polymer gel for the treatment of herpes simplex virus type 1 (HSV-1)-induced viral corneal keratitis. Nanoparticles containing prodrugs of GCV were prepared by a double-emulsion solvent evaporation technique using various PLGA polymers with different drug/polymer ratios. Nanoparticles were characterized with respect to particle size, entrapment efficiency, polydispersity, drug loading, surface morphology, zeta potential and crystallinity. Prodrugs-loaded NP were incorporated intoin situgelling system. These formulations were examined forin vitrorelease and cytotoxicity. The results of optimized entrapment efficiencies of LLGCV-, LDGCV- and DLGCV-loaded NP are of 38.7 ± 2.0%, 41.8 ± 1.9%, and 45.3 ± 2.2%; drug loadings 3.87 ± 0.20%, 2.79 ± 0.13% and 3.02 ± 0.15%; yield 85.2 ± 3.0%, 86.9 ± 4.6% and 76.9 ± 2.1%; particle sizes 116.6 ± 4.5, 143.0 ± 3.8 and 134.1 ± 5.2 nm; and zeta potential −15.0 ± 4.96, −13.8 ± 5.26 and −13.9 ± 5.14 mV, respectively. Cytotoxicity studies suggested that all the formulations are non-toxic.In vitrorelease of prodrugs from NP showed a biphasic release pattern with an initial burst phase followed by a sustained phase. Such burst effect was completely eliminated when NP were suspended in thermosensitive gels with near zero-order release kinetics. Prodrugs-loaded PLGA NP dispersed in thermosensitive gels can thus serve as a promising drug delivery system for the treatment of anterior eye diseases. [ABSTRACT FROM AUTHOR]

Excessive price and scarcity of Pt species make it very necessary to enhance the atom utilization and catalytic efficiency of Pt catalysts for implementing their industrial practicality. Here, natural cotton is adopted as the precursor to in-situ support well-dispersed and uniform-sized Ni nanoparticles, which then work as nanoislands to effectively deposit single-atom Pt via the galvanic replacement reaction. On the resulting fibrous carbon matrix, the monocrystalline Ni particles are verified to tightly anchor isolated Pt atoms to form the alloyed PtNi nanoparticles. In the 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP), the catalytic activity of the bimetallic PtNi/C catalyst with the low Pt loading (0.81%) maximally reaches 25 times as high as the primary Ni/C product. Simulated calculations demonstrate that the single-atom Pt centers on PtNi nanoparticles rapidly capture and split H 2 molecules, while Ni atoms strongly adsorb 4-NP molecule to activate the -NO 2 group. Therefore, the trapped H atom could easily attack the -NO 2 and reduce 4-NP. Cotton is utilized to in-situ prepare well-dispersed and uniform-sized PtNi/C bimetallic catalysts with the superior activity in the 4-nitrophenol reduction. [Display omitted] • Natural cotton has been utilized for fabricating the Ni/C catalyst. • Ni nanoparticles work as nanoislands to deposit single-Atom Pt, forming PtNi nanoparticles. • The PtNi/C catalyst exhibits a great catalytic performance for reduction of 4-NP. • Catalytic mechanism of the PtNi/C bimetallic catalyst has been explored. [ABSTRACT FROM AUTHOR]

Protein-based nanoparticles hold great promises in both preclinical and clinical practices, such as oncology diagnosis and treatment, because of their high biocompatibility and biodegradability. However, the complicated preparation and lack of targeting specific cells or tissues may limit their further uses. To overcome these limitations, we developed a novel replacing method for preparing dual-functional protein nanocarrier, such that one function is capable of encapsulating small molecule into protein, whereas the other function is cable of recognizing CD163 receptor [hemoglobin (Hb) scavenger receptor]. In this study, Hb was chosen as the targeting drug carrier. First, the heme group in the Hb was removed and replaced by paclitaxel (PTX) to form nanoparticles (Gb-NPs-PTX). The resulted Gb-NPs-PTX showed spherical shape and their diameter could be controlled in the range of 120-160 nm by altering the ratio of PTX to Hb. The binding activity of Gb-NPs-PTX to CD163 was confirmed by cell uptake in CD163+ Chinese hamster ovary cells. Results in vivo also showed a CD163-dependent tissue accumulation of Gb-NPs-PTX in mice. In summary, by using the novel replacing method, PTX could be easily encapsulated into Hb nanoparticles and the targeting effects of Hb could also be kept. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:1045-1055, 2015 [ABSTRACT FROM AUTHOR]

Because of abundant oxygen-based groups, natural cotton is adopted as the precursor to in situ fabricate a three-dimensional (3D) Bi 2 O 3 -supported carbon fiber aerogel (Bi 2 O 3 /CF). The calcination temperature plays an important role in the crystal composition of Bi species and the specific surface area of the aerogel. When the calcination temperature is 800 °C, the Bi 2 O 3 /CF product exhibits the highest tetracycline (TC) removal efficiency, including large adsorbability and superior photocatalytic activity. Furthermore, its 3D porous network architecture provides a multidimensional open framework for the free mobility of solution and rapid diffusion of reactants and products. In the flowing system, the 3D Bi 2 O 3 /CF aerogel can implement the continuous and stable elimination of pollutants for a long time, and it does not require any separation operation. Consequently, the 3D Bi 2 O 3 /CF aerogel is expected as a promising functional material to massively remove organic pollutants from industrial wastewater. Cotton is utilized to in-situ synthesize the 3D Bi 2 O 3 -supported carbon fiber aerogel to continuously remove tetracycline in a flowing system. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A facile strategy by loading luminol and secondary antibody on gold nanoparticles (Au NPs) was described in the present work. The as-prepared luminol/antibody labeled Au NPs conjugates (LAAu NPs) were used as the chemiluminescent probe for the detection of carcinoembryonic antigen (CEA) in serum. The LAAu NPs were characterized by transmission electron microscopy (TEM), UV–vis spectrophotometry (UV–vis), and chemiluminescent method. Stable and efficient chemiluminescence (CL) was obtained when luminol molecules and secondary antibodies were coimmobilized on the Au NPs by using hydrogen peroxide (H2O2) as an oxidant, horseradish peroxidase (HRP) as a catalyst, and 4-(4′-iodo)phenylphenol (IPP) as an enhancer. The LAAu NPs were further evaluated via a sandwich-type CL immunoassay of CEA in serum. In this protocol, the CEA analyte was captured by the primary antibody immobilized on the surface of magnetic beads, and then was sandwiched by the secondary antibody loaded on luminol-labeled Au NPs. The chemiluminescent intensity was proportional to the concentration of CEA over the range of 5.0×10−10 to 5.0×10−8 gmL−1 and 5.0×10−9 to 2.0×10−8 gmL−1 by using HRP and Co2+ as catalysts, respectively. The present chemiluminescent immunoassay based on the luminol/antibody labeled Au NPs conjugates has offered great promise for simple, highly biocompatible, and cost-effective analysis of biological samples. [Copyright &y& Elsevier]

• In-situ growth of superlattice structure Cu 2 S nanoparticles on MoS 2 nanosheets has been achieved. • l -cysteineconjugated with sulfur defects on exfoliated MoS 2 nanosheets was exhaustively studied. • The intense interfacial effects are formed between Cu 2 S and MoS 2 for 2-Cu 2 S-MoS 2 sample. • 2-Cu 2 S-MoS 2 shows enhanced photoreduction efficiency of Cr(VI) and superior stability. • The strategy is extended to successfully construct CdS-MoS 2 and ZnS-MoS 2 heterojunctions. For obtaining ultra-fine Cu 2 S nanoparticles with reduced recombination of their photogenerated electron/hole pairs, in-situ growth of Cu 2 S nanoparticles on exfoliated MoS 2 nanosheets was achieved in this study. We have exhaustively studied l -cysteine in-situ conjugation with sulfur defects on the surface of MoS 2 nanosheets, which makes particle-level superlattice structured Cu 2 S nanoparticles (average 6.2 nm) well disperse on MoS 2 nanosheets. Further, XPS and Raman analysis confirm that the intense interfacial effects are formed between Cu 2 S and MoS 2 for the 2-Cu 2 S-MoS 2 composite, which significantly promote separation of photogenerated electron-hole pairs and prolong their lifetime, as shown by PL and TRPL. As a result, 2-Cu 2 S-MoS 2 exhibits the fastest photoreduction rate of Cr(VI) (0.0058 min−1) under visible light irradiations, which are almost 8.3 times and 2.9 times higher than that of MoS 2 nanosheets (0.0007 min−1) and pure Cu 2 S (0.002 min−1), respectively. Meanwhile, 2-Cu 2 S-MoS 2 also possesses an optimal composite proportion between Cu 2 S and MoS 2 , which presents outstanding photocatalytic activity among series of x-Cu 2 S-MoS 2 composites. The photoreduction mechanism of Cr(VI) is investigated in detail. As a matter of fact, l -cysteinecoupled with sulfur defects on MoS 2 nanosheets could produce the coordination inner heterojunction interface of 2-Cu 2 S-MoS 2 samples, which greatly improves migration efficiency of photoinduced carriers and ultimately endows it outstanding photoreduction activities. Furthermore, the strategy was extended to fabricate CdS-MoS 2 and ZnS-MoS 2 heterojunctions, implying that this strategy is of promising potentials for designing more active metal sulfides heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon nanotubes (N-CNTs)/gold composites were synthesized through a simple self-assembly method. The morphology, composition, and optical properties of the resulted composites were investigated by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectra, ultraviolet-visible absorption spectrum, and X-ray photoelectron spectroscopic. This nanocomposite combines the advantages of N-CNTs and gold nanoparticales showing many excellent properties such as good dispersibility in water and satisfactory biocompatibility. Cyclic voltammogram experiment shows that N-CNTs/gold composite has high conductivity. Based on these aspects, N-CNTs/gold-modified electrode was applied to the voltammetric determination of thioridazine hydrochloride (TH) successfully. The linear calibration range for the TH sensor was 12 ~ 850 μM with a detection limit of 1.3 μM at a signal-to-noise ratio of 3, long-term stability, and good reproducibility. [ABSTRACT FROM AUTHOR]

A nanoparticle magnetic resonance imaging (MRI) contrast agent targeted to liver was developed by conjugation of gadolinium (Gd) chelate groups onto the biocompatible poly( l-lactide)-block-poly (ethylene glycol) (PLA-PEG) nanoparticles. PLA-PEG conjugated with diethylenetriaminopentaacetic acid (DTPA) was used to formulate PLA-PEG-DTPA nanoparticles by solvent diffusion method, and then Gd was loaded onto the nanoparticles by chelated with the unfolding DTPA on the surface of the PLA-PEG-DTPA nanoparticles. The mean size of the nanoparticles was 265.9 ±± 6.7 nm. The relaxivity of the Gd-labeled nanoparticles was measured, and the distribution in vivo was evaluated in rats. Compared with conventional contrast agent (Magnevist), the Gd-labeled PLA-PEG nanoparticles showed significant enhancement both on liver targeting ability and imaging signal intensity. The T1 and T2 relaxivities per [Gd] of the Gd-labeled nanoparticles was 18.865 mM−−1 s−−1 and 24.863 mM−−1 s−−1 at 3 T, respectively. In addition, the signal intensity in vivo was stronger comparing with the Gd-DTPA and the T1 weight time was lasting for 4.5 h. The liver targeting efficiency of the Gd-labeled PLA-PEG nanoparticles in rats was 14.57 comparing with Magnevist injection. Therefore, the Gd-labeled nanoparticles showed the potential as targeting molecular MRI contrast agent for further clinical utilization. [ABSTRACT FROM AUTHOR]