RSC Advances

Chen, Yiping; Xie, Mengxia

doi: 10.1039/c5ra19126bpmid: N/A

We developed a magnetic relaxation switching immunosensor for the detection of salbutamol using a gold nanoparticles–streptavidin conjugate and magnetic nanoparticles. This immunosensor enables faster detection with enhanced sensitivity compared with enzyme-linked immunosorbent assay, providing a promising platform for rapid sensing of small molecules.

Xie, Wanfeng; Song, Hui; Fan, Jihui; Jiang, Feng; Yuan, Huimin; Zhang, Shiyu; Wei, Zhixian; Pang, Zhiyong; Han, Shenghao

doi: 10.1039/c5ra22241apmid: N/A

Ultra-long crystalline Alq3 1 dimensional (1D) materials were prepared by using an extremely facile solution approach without any surfactant, SDS, anti-solvent, or other reagents. The Alq3 1D materials have smooth surfaces and pentagonal or hexagonal cross-sections. The length of the microrods have α-phase crystalline structures. The prepared Alq3 samples exhibit excellent green-light photoluminescence (PL) performance. The growth mechanism of the Alq3 1D structures were discussed. The limitation conditions of the Alq3 microrods were also studied. In addition, the influence of the volume of CHCl3 on the microrods was discussed. This controllable growth method can potentially be extended to other functional organic nanomaterials.

Alexandru, Maria-Gabriela; Visinescu, Diana; Marino, Nadia; de Munno, Giovanni; Lloret, Francesc; Julve, Miguel

doi: 10.1039/c5ra16307bpmid: N/A

The use of the cyanide-bearing complexes PPh4[CoIII(4,4′-dmbipy)(CN)4] and PPh4[CoII(dmphen)(CN)3] as metalloligands towards [Mn(salen)(H2O)]ClO4 affords one-dimensional coordination polymers with the formulas {[MnIII(salen)(μ-NC)2CoIII(4,4-dmbipy)(CN)2]·H2O}n (1) and {[MnIII(salen)(μ-NC)2CoIII(dmphen)(CN)2]}n (2) [PPh4+ = tetraphenylphosphonium cation, 4,4′-dmbipy = 4,4′-dimethyl-2,2′-bipyridine, dmphen = 2,9-dimethyl-1,10-phenanthroline and H2salen = N,N′-ethylenebis(salicylideneimine)]. Compounds 1 and 2 were structurally characterized. Their structures consist of neutral chains with regular alternating [Mn(salen)]+ and [CoIII(4,4′-dmbipy)(CN)4]− (1)/[CoIII(dmphen)(CN)4]− (2) moieties, the latter ones acting as bis-monodentate ligands towards the Mn(iii) units through two of their four cyanide groups. During the synthesis, the cobalt(ii) ion of the starting [CoII(dmphen)(CN)3]− metalloligand is oxidized to Co(iii) and it takes an additional cyanide ligand to transform into {CoIII(dmphen)(CN)4} in 2. Magnetic studies have been carried out on 1 and 2 in the temperature range 1.9–300 K which yielded local negative zero-field splitting parameters of −3.26 (1) and −4.38 cm−1 (2). Frequency-dependent alternating current susceptibility signals under an external applied magnetic field (dc) were clearly observed for 1 and 2 indicating slow magnetic relaxation, that is, Single Ion Magnet (SIM) behaviour. The energy barriers (Ea) to reverse the magnetization direction under an applied dc magnetic field of 2000 Oe were 12.0(2) (1) and 9.4(3) cm−1 (2), whereas the values of the pre-exponential factor (τo) were 1.40(2) × 10−8 (1) and 2.5(2) × 10−8 s (2).

Irfan, Masooma; Basri, Hatijah; Irfan, Muhammad; Lau, Woei-Jye

doi: 10.1039/c5ra11344jpmid: N/A

Membrane fouling is one of the main challenges encountered in ultrafiltration (UF) processes and the use of nanoparticles for the improvement of UF performance is a recent trend in membrane technology. In this study, in order to improve surface characteristics of polyethersulfone (PES)-based membranes for greater resistance against biofouling, PES was incorporated with a new type of nanocomposite (NC) in which the NC could be synthesized by blending acid functionalized multiwalled carbon nanotubes (f-MWCNT) with polyvinylpyrrolidone (PVP) in dimethylformamide (DMF). The chemistry of the NCs embedded within the PES membrane matrix was analysed by FTIR, whereas the fabricated membranes were characterized by FESEM, contact angle, water absorption tests, surface profile studies and their filtration performances with respect to pure water permeation, antifouling resistance against proteins and flux recovery rate. The results revealed that, compared to the pristine PES membrane, the antifouling ability of the PES membrane incorporated with f-MWCNT/PVP NC is greater, recording 81.7% flux recovery and 80.2% total resistance (>76% were reversible one). The protein separation results indicated that, the NCs based membrane was able to reject 93.4%, 74.7%, 59.4% and 28.5% for bovine serum albumin (66 kDa), pepsin (34.6 kDa), trypsin (20 kDa) and (14.6 kDa), respectively.

Roy, Ekta; Patra, Santanu; Saha, Shubham; Madhuri, Rashmi; Sharma, Prashant K.

doi: 10.1039/c5ra18575kpmid: N/A

Herein, we have synthesized four different shapes (spherical, oval, rod and flower shape) of silver nanoparticles (AgNPs) using a green synthesis approach via microwave-assisted synthesis. The nanoparticles were synthesized using pomegranate juice as a novel reducing agent. The synthesized AgNPs were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and tunnelling electron microscopic (TEM) analysis. The as-prepared AgNPs show a very rapid, effective, shape-specific and dose-dependent bacteriostatic/bactericidal effect towards four different bacterial strains (two Gram negative and two Gram positive). The analysis was determined by different methods such as a disc diffusion study, growth curve analysis, minimum inhibitory concentration and minimum bactericidal concentration determinations. Amongst the four different shaped AgNPs, the flower shaped AgNPs demonstrated the best results and mediated the fastest bactericidal activity against all the tested strains at similar bacterial concentrations. The results were also confirmed by confocal microscopic analysis. Additionally, the flower shaped AgNPs have the ability to non-specifically remove various bacterial strains from a real water sample with ∼98% removal efficiency, as compared to other synthesized different shaped nanoparticles.

Plonska-Brzezinska, M. E.; Bobrowska, D. M.; Sharma, A.; Rodziewicz, P.; Tomczyk, M.; Czyrko, J.; Brzezinski, K.

doi: 10.1039/c5ra15469cpmid: N/A

Because collagen is the most abundant component of connective tissue, it is an excellent biomaterial in numerous medical applications. However, the utility of collagen is limited by its low mechanical strength in aqueous solutions and its susceptibility to proteolytic degradation in vivo. To improve the physical properties of collagen and to enhance its chemical resistance, it is necessary to stabilize its structure through chemical or physical modifications. In this study, we analyzed the interactions of a model molecule, a synthetic triple helical collagen-like peptide, with polyphenols such as curcumin, rutin, quercetin, naringin, and hypericin. Interactions between the peptide and polyphenolic compounds were analyzed using various techniques. The layer-by-layer assembly processes of a gold surface using the peptide and polyphenols was performed via surface plasmon resonance (SPR), atomic force microscopy (AFM), and ellipsometry. SPR screening of polyphenols was conducted in real time to select compounds that bind to the collagen-like peptide and could thus be applied to the stabilization of collagen. Selected polyphenols, especially naringin and hypericin, demonstrated notable binding to the peptide. To determine the nature of these interactions, experiments were supplemented with crystallographic studies and molecular docking of plant metabolites and collagen-like peptides.

Liu, Xiao; Liu, Hong-Ling; Fang, Ning; Li, Xue-Mei; Guo, Wei-Hua; Wu, Jun-Hua; Zhao, Mei-Xia

doi: 10.1039/c5ra14410hpmid: N/A

Multifunctional high-performance La1−xSrxMnO3@Au core–shell nanoparticles were successfully synthesized by a modified nanoemulsion method with the assistance of poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO). X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirm the structure and morphology of the nanoparticles. The measurements obtained using ultraviolet-visible light absorbance spectrometry (UV-vis), vibrating sample magnetometry (VSM), and a physical property measurement system (PPMS) demonstrate that the nanoparticles exhibit a surface plasmon resonance (SPR) absorption band around 561 nm from nanostructured Au and a unique magnetic nature at room temperature. Particularly, a sharp, tight phase transition from ferromagnetic to superparamagnetic states is observed in a free-standing La1−xSrxMnO3 nanoparticle system for the first time with a Curie temperature around room temperature. The cytotoxicity of the nanoparticles was studied for safe biomedical applications using an MTT assay. The results show that the La1−xSrxMnO3@Au core–shell nanoparticles with lower cytotoxicity, well-defined magnetic and optical properties are promising for optical, magnetic, and biomedical application.

Zeng, Shangjing; Wang, Runwei; Zou, Yongcun; Fu, Jingru; Zhang, Zhongtao; Qiu, Shilun

doi: 10.1039/c5ra17625epmid: N/A

A promising strategy for synthesis zeolites has been reported in this paper. The method combines the advantages of both microwave heating and solventless synthesis. This method can generate zeolites under atmospheric pressure and is safe, highly efficient and environmentally benign.

Serafim, A.; Cecoltan, S.; Lungu, A.; Vasile, E.; Iovu, H.; Stancu, I. C.

doi: 10.1039/c5ra14361fpmid: N/A

Nanotechnology and biomimicry represent appealing but still underexploited techniques to develop innovative scaffolds with ECM-inspired features for tissue engineering. In the present work we have investigated the potential of a combination of two designed elements to trigger enhanced bio-interactions with bone regeneration potential: COOH-functionalized nanodiamond particles (COOH-NDPs) have been loaded for the first time into electrospun fish gelatin hydrogel fibers thus generating nanocomposite fibrous scaffolds with interconnected porosity. When compared to control fish gelatin fibers, no significant modification of the mineralization capacity in acellular simulated body fluid has been evidenced by micro-structural and spectroscopic investigations, for fibers with COOH-NDPs content ranging from 0.25% to 1%. It is important to mention that, following Ca/P alternate incubation, nano-apatite crystals were preferentially developed and firmly adhered on the fiber regions in the proximity of COOH-NDPs, as proven by transmission electron microscopy (TEM). Significant mineralization occurred in the culture media in the presence of MG63 osteoblast-like cells and seems to be directly stimulated by the presence of the nanoparticles. Altogether, these findings emphasize the ability of NDPs to enhance, when immobilized in gelatin fibers and exposed to specific media, the formation of apatite. It was also noticed that the number of adherent MG63 cells, their morphology and spreading were improved by increasing the amount of NDPs in the fibers (fluorescence and scanning electron microscopy). This work successfully proves the potential of such nanocomposite fibers to find applications in bone regeneration.

liu, Qiang; Ding, Dongyan; Ning, Congqin; Wang, Xuewu

doi: 10.1039/c5ra21805epmid: N/A

This work reports the facile synthesis of reduced N/Ni-doped TiO2 nanotubes photoanodes and their photocatalytic activity application. The obtained photoanodes were characterized by scanning electron microscope (SEM), Raman spectrum (Raman), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance absorption spectra. The narrowed band gap of TiO2 due to the doping of N and Ni elements could enhance the light absorption effectively. The NaBH4 reduction process resulted in the formation of oxygen vacancies in photoanodes. The electrochemical characterization revealed that photo-induced carriers were more efficient charge separation and transportation in reduced N/Ni-doped TiO2 nanotubes photoanodes. The highest photocurrent density obtained from reduced N/Ni-doped TiO2 nanotubes photoanodes was 2.52 mA cm−2 at 0 V vs. Ag/AgCl in 1 M KOH solution, which was about five times as high as that obtained from undoped TiO2.