RSC Advances

Liang, Gaoling; Zhao, Zhongjun; Wei, Yin; Liu, Kunping; Hou, Wenqian; Duan, Yixiang

doi: 10.1039/c5ra02910dpmid: N/A

A simple, label-free and cost-effective localized surface plasmon resonance (LSPR) immunosensing method was developed for detection of alpha-fetoprotein (AFP). The U-bend fiber optic probe was firstly pretreated by microwave-induced H2O/Ar plasma to ensure better silanization, which could greatly improve the adsorbed amounts and uniformity of the gold nanoparticles (GNPs) on the fiber optic probe surface. Furthermore, according to the sucrose refractive index (RI) testing result, the absorbance sensitivity to RI change of this sensor was obviously improved due to the plasma pretreatment. Finally, on the basis of this U-bend strategy and plasma pretreated method, the fabricated biosensor displayed good analytical performance for detection of AFP, ranged from 5 to 200 ng mL−1 in both phosphate-buffered saline (PBS) and human serum, with different detection limits of 0.85 and 3.3 ng mL−1 respectively. Therefore, the present strategy definitely paves a way for wider applications of LSPR in clinical research and may eventually become a promising technique for protein detection.

Manhas, Navdeep; Balasubramanian, K.; Prajith, P.; Rule, Prashant; Nimje, Sunil

doi: 10.1039/c4ra17191hpmid: N/A

The convenient exploitation of biodegradable and biocompatible PCL/PVA polymers in the field of tissue engineering is limited by their inferior mechanical, thermal and barrier properties. The present study thereby aspires towards supplementing their mechanical properties by exploiting the merits of nanofiber reinforcement and state of the art electrospinning processes. These processes generate nanofibers that can be employed as reinforcing fillers in the synthesis of biocomposites possessing high strength and toughness towards tissue engineering applications. We have demonstrated a green, inexpensive, low energy consuming and one-step technique of steam explosion with lemon juice using an in-house conceptualized autoclave for the disintegration of cellulose micro/nanofibrils from lignocellulosic material. An enhancement in the crystallinity of the native cellulose from 43 to 63% was confirmed by XRD characterization using a peak deconvolution method, and FTIR spectra validated the grafting of the carboxylic groups in citric acid with cellulose fibrils providing the surface modification and superior interaction with a hydrophobic polymer matrix. Thereafter, PCL/PVA polymers were nanoengineered by electrospinning along with the steam explosion generated cellulose micro/nanofibrils to yield PCL/PVA nanoencapsulated cellulose nanofibrils of diameter 40–70 nm, owing to the diffusion of the polymeric material into the porous network of the cellulose fibrils. The resulting fibrils with enhanced surface area, reduced surface roughness and reduced pore size have also displayed antimicrobial properties against Staphylococcus aureus and Escherichia coli bacterial strains, and thus can be used as reinforcing nanoadditives in known biocompatible polymers to give rise to novel biocomposites with enhanced mechanical properties.

Xu, Weihua; Wang, Shufan; Liu, Yunguo; Zeng, Guangming; Zheng, Bohong; Tan, XiaoFei; Li, Tingting; Wang, Hui; Guo, Fangying; Zhang, Mingming

doi: 10.1039/c4ra17248epmid: N/A

Pleurotus ostreatus was modified by tartaric acid and used as a biosorbent for the removal of Cr(vi) from aqueous solution. The removal efficiency of Cr(vi) by the modified P. ostreatus was 2 to 2.5 times higher than by pristine P. ostreatus. FTIR and XPS analysis indicated that carboxyl and amino groups were the major functional groups for Cr(vi) sorption. Batch sorption experiments were carried out to investigate the characteristic adsorption behavior of MPOD. Experimental data fitted a pseudo-second order equation and the Freundlich isotherm. The optimum biosorption was observed at pH 2.0 with the biosorption capacity was 99.66 mg g−1. Thermodynamic analysis showed that the adsorption process was spontaneous and endothermic. The present results confirmed that electrostatic attraction and complexation were involved in Cr(vi) removal. Modified P. ostreatus has the characteristics of simplicity and obvious effects for the removal of Cr(vi) ions from aqueous solution.

Liu, Xianguo; Wu, Niandu; Cui, Caiyun; Bi, Nannan; Sun, Yuping

doi: 10.1039/c4ra14753gpmid: N/A

Fe3O4/MnO2 core–shell structured nanocomposites have been synthesized by a one-pot approach at ambient temperature and pressure. The morphology of the prepared Fe3O4/MnO2 nanoparticles is governed by the Mn/Fe molar ratio in the precursor. When the molar ratio of Mn/Fe is 1 : 10, the nanocomposites exhibit a special microstructure, in which MnO2 nanorods are formed on the surface of spherical Fe3O4 nanoparticles. With the increase of the Mn/Fe ratio to 1 : 2, core–shell structured nanoparticles with Fe3O4 nanoparticles as cores and MnO2 as the shell are obtained. The microwave absorption properties of the core–shell Fe3O4/MnO2 nanocomposites were studied in the 2–18 GHz frequency range. The microwave absorption performance of the Fe3O4/MnO2 nanocomposites exhibited a remarkable enhancement in comparison with pure Fe3O4 nanoparticles, ascribed to the fact that MnO2 nanostructures can improve the dielectric loss factor and the electromagnetic (EM) matching degree. The absorption peaks of the Fe3O4/MnO2–paraffin composites are red shifted compared to those of Fe3O4–paraffin composites. Due to the MnO2 nanorods on the surface of the Fe3O4 nanoparticles, the produced microcurrent can reduce the electron transition energy and lead to better microwave absorption by the Fe3O4 nanoparticle/MnO2 nanorod nanocomposites.

Hou, Yi; Chen, Chen; Liu, Kemin; Tu, Ying; Zhang, Li; Li, Yubao

doi: 10.1039/c5ra01280epmid: N/A

Polyvinyl alcohol (PVA) hydrogels with high-transparence were prepared by dissolving PVA powders into dimethyl sulfoxide (DMSO) aqueous solutions with different concentrations to obtain 16.7 wt% PVA hydrogels followed by several freeze–thaw cycles. The transparence, crystallinity, mechanical strength and compositions of the PVA hydrogels were tested and analyzed by using a spectrophotometer, a universal testing machine and infrared spectroscopy (IR), indicating that when the concentration of DMSO was 80 wt%, the transparence of the PVA hydrogel displayed a maximum value of 99.8 ± 0.2%, close to that of the natural human cornea (99.7–99.9%), which is closely related to the interaction between DMSO and H2O molecules as well as the crystallinity of the PVA hydrogel. Based on this, the interaction between DMSO and H2O molecules and the transparent mechanism were also explored. It has been found that the viscosity of the DMSO aqueous solution reaches the maximum value when its concentration is 68.5% and is prone to be affected by temperature, while the 80 wt% DMSO aqueous solution endows the PVA hydrogel with the highest transparence. Based on IR and DSC analysis, the spatial structures of the PVA hydrogels prepared with different DMSO aqueous solutions were schematised, and it was thought that the formation of a 1DMSO/2H2O network structure contributes the most to the crystallinity and the transparence of the PVA hydrogel. Such a PVA hydrogel with high transparence could have great potential to be used as the optical core of an artificial cornea.

Guan, Yu; Hu, Song; Wang, Ying; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

doi: 10.1039/c5ra00879dpmid: N/A

Considering environmental pollution, disposal costs, the high-value of isopropanol (IPA) and other factors, recovering isopropanol from industrial effluent is considered to be attractive, practical and cost-effective. However, the separation techniques including gas stripping, distillation, and pervaporation often yield low selectivity and high energy consumption. In this paper, a process of integrating gas stripping and vapor permeation was conducted for separating isopropanol from dilute solutions. A PDMS (polydimethylsiloxane) membrane was prepared by using a green method. The effects of gas flow rate, membrane model temperature, feed solution temperature, and feed solution concentration on the performance of the separation system were investigated. The results in this study showed that the optimized separation performance (isopropanol flux 437.8 g m−2 h−1, separation factor 125.8) was obtained for separating 3 wt% isopropanol solution at 75 °C, which were 1.48 times and 7.4 times of those obtained in the PV process. The energy consumption of evaporation was only 1.28 MJ kg−1; this was 26% and 30% of the evaporation energy needed for the PV process and the distillation process at the same conditions. Additionally, a comparison of separation performance with other separation techniques was also conducted in the study.

Pariente-Cohen, Natalie; Weitman, Michal; Tania, Nassdyuk; Major, Dan T.; Gottlieb, Hugo E.; Hoz, Shmaryahu; Nudelman, Abraham

doi: 10.1039/c5ra01016kpmid: N/A

Attempted acylation of the anticancer agent hydroxyurea (HU) with acyl chlorides or anhydrides led to acylation on the NH group rather than on the OH. The structures of the products were confirmed by 15N-HMBC NMR. An analogous reaction conducted with hydroxamic acids (RCONHOH) or N-hydroxycarbamates (ROCONHOH) led to acylation on the OH. Surprisingly, despite the established affinity of phosphorous to O, phosphorylation of HU also took place at the NH group instead of the OH. These results are rationalized based on the different dominant resonance structures of HU, the hydroxamic acids or the N-hydroxycarbamates.

Ai, Wensi; Shi, Ronghua; Zhu, Liyan; Jiang, Dehong; Ma, Xiaobo; Yuan, Jilan; Wang, Zhouyu

doi: 10.1039/c5ra01536gpmid: N/A

A novel, efficient and atom economical one pot protocol for the synthesis of N-(β-nitro)amides has been described by combining the Henry reaction with the Ritter reaction. The designed products could be obtained from easily available aldehydes, nitroalkanes and nitriles with 60–83% overall yields under mild reaction conditions. In addition, the product can easily be transformed into diamine or protective amine derivatives.

Liu, Tian; Liu, Xunwei; Yao, Yanjie; Zhou, Juan; Zhu, Jun; Sun, Gang; He, Dannong

doi: 10.1039/c5ra01120epmid: N/A

Multimodality molecular imaging has recently attracted much attention, because it can take advantage of individual imaging modalities by fusing together information from several molecular imaging techniques. Herein, we report a bifunctional contrast agent connecting MR and luminescent imaging. The bifunctional contrast agent, carbon@Gd-DTPA microspheres, arise from carbon microspheres, which are synthesized on a large scale through a Na3cit-assisted solution route. The T1-agent, Gd-DTPA, is then conjugated to the carbon microspheres through N-ethyl-N9-[3-(dimethylamino)propyl]carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) coupling chemistry using surface absorbed Na3cit molecules as an intermedium. Meanwhile, a formation mechanism of the carbon microspheres has been suggested. Furthermore, we also prove that the application of the carbon@Gd-DTPA bifunctional contrast agents for MR imaging and luminescent imaging can be established successfully. These results show that the primary Na3cit molecules have been confirmed to serve triplicate roles as an oriented agent to produce carbon microspheres, an intermedium to conjugate Gd-DTPA and surface passivation agents to improve photoluminescence.

Liu, Fuming; Xie, Yu; Yu, Changlin; Liu, Xiaoming; Dai, Yuhua; Liu, Lianjun; Ling, Yun

doi: 10.1039/c5ra00187kpmid: N/A

Titanium dioxide (TiO2) has been intensively used as a photocatalyst for the degradation of organic pollutants in water, but is typically obstacle by a low efficiency, costly separation, limited visible light response, and poor recyclability. Herein, we provided a reliable method to simultaneously tackle these four obstacles by developing an integrated and multifunctional hybrid photocatalyst/magnetic material, i.e., Sr–TiO2/Ni0.6Zn0.4Fe2O4. This novel hybrid not only demonstrated a high efficiency (90–100%) and a good cycling performance (90% maintenance) for photodegradation of bisphenol A (BPA) under both UV and visible light irradiation, but it can also efficiently work at a wide pH range (4–10) and can be easily separated from water for reuse only by introducing an external magnetic field. The materials structure-to-activity correlation has also been investigated. It was found that doping Sr2+ and a coupling magnetic material with TiO2 could extend the visible light response and create active defects in TiO2, which were responsible for the nearly three times higher activity than that of commercial TiO2(P25) under visible light. On the other hand, doping excessive Sr2+ lowered the surface area, enlarged the crystalline size and caused particle aggregation; thus, leading to a decrease in photocatalytic activity of the hybrid. These further modifications in the hybrid materials can provide a competitive alternative to control the organic pollutants in waste water.