Facile synthesis of a nanocomposite based on graphene and ZnAl layered double hydroxides as a portable shelf of a luminescent sensor for DNA detectionLi, Hongjuan; Wen, Jia; Yu, Ruijin; Meng, Jia; Wang, Cong; Wang, Chaoxia; Sun, Shiguo
doi: 10.1039/c4ra15395bpmid: N/A
Recently, nanocomposites based on graphene and layered double hydroxides (LDH) have been developed and used in many fields. However, to the best of our knowledge, there is no report on the luminescence sensor applications of graphene/LDH composites. Herein, a hybrid graphene–ZnAl-LDH nanocomposite has been developed using a facile one-step process and the presence of LDH in the composite can effectively prevent the restacking of graphene and improve both its luminescence properties and thermal stability. Furthermore, the composite can be used as a portable shelf of the Ru(phen)3Cl2 (tris(1,10-phenanthroline)ruthenium(ii) dichloride) sensor to selectively discriminate DNA. It was found that the graphene–ZnAl-LDH composite can effectively quench the emission of the Ru(phen)3Cl2 sensor. After the addition of a certain amount of DNA into the system, Ru(phen)3Cl2 was released from the graphene–ZnAl-LDH composite and it interacted with DNA immediately, leading to the luminescence recovery of the sensor. The results indicate that the RGO–ZnAl-LDH composite displayed an excellent luminescence response and good linear correlation to DNA. Therefore, the composite can be employed as a portable shelf of Ru(phen)3Cl2 to discriminate DNA. Moreover, both the shelf and the sensor can be easily collected and made ready for the next sample if there is no DNA in the solution. The proposed method was further applied to detect the immunodeficiency virus gene (HIV), thus providing a new field of application for hybrid graphene/LDH composites.
Hydrolysis of cellobiose to monosaccharide catalyzed by functional Lanthanum(iii) metallomicellePeng, Xiao; Meng, Xiang-Guang; Mi, Chun; Liao, Xiao-Hong
doi: 10.1039/c4ra14521fpmid: N/A
A novel surfactant, 3-(dodecylimino)butan-2-one-oxime (DMBO), was synthesized. The metallomicelle La(DMBO)2 was prepared and used as a mimic of β-glucosidase to catalyze the hydrolysis of cellobiose in weakly alkaline aqueous solution at relative low temperature (80–110 °C). This study indicated that the functional metallomicelle displayed effective catalytic activity for hydrolysis of cellobiose to monosaccharide (glucose, fructose and 1,6-anhydroglucose) and glucosyl-erythrose. The conversion of cellobiose and selectivity of monosaccharide could reach 38.5% and 71.1%, respectively, for a reaction time of 10 h at pH 9.0 and 95 °C. The possible reaction pathways of cellobiose hydrolysis are proposed and the catalysis reaction rate constant kcat and Michaelis constant Km for the cellobiose hydrolysis were calculated. The apparent activation energy (Ea = 84.6 kJ mol−1) of cellobiose to monosaccharide was evaluated.
Efficacy of variable dosage of aspirin in combating methotrexate-induced intestinal toxicityGupta, Sukesh K.; Gautam, Swetlana; Rawat, Jitendra K.; Singh, Manjari; Saraf, Shubhini A.; Kaithwas, Gaurav
doi: 10.1039/c4ra13640cpmid: N/A
The aim of the present study was to study in detail the effect of variable doses of aspirin on intestinal toxicity. Albino rats were randomly divided into six groups and subjected to 13 weeks treatment against a sham control (3 ml kg−1 by mouth (p.o.) normal saline); a toxic control (2.5 ml kg−1 intraperitoneal injection (i.p.), MTX); a low dose of aspirin (8 mg kg−1, p.o.); a low dose of aspirin plus MTX (8 mg kg−1, p.o. + 2.5 ml kg−1, i.p.), a high dose of aspirin (45 mg kg−1, p.o.); and a high dose of aspirin plus MTX (45 mg kg−1, p.o. + 2.5 ml kg−1, i.p.). The intestinal toxicity of aspirin was assessed on the basis of biochemical changes and modulation in the inflammatory markers. Low doses of aspirin gave significant protection against MTX-induced toxicity, whereas high dose failed to do so. High doses of aspirin also produced adverse biochemical changes in the physiology, but low dose did not.
Interaction of the core fragments of the LL-37 host defense peptide with actinSol, Asaf; Wang, Guangshun; Blotnick, Edna; Golla, Radha; Bachrach, Gilad; Muhlrad, Andras
doi: 10.1039/c4ra13007cpmid: 26726303
Host defense peptides are effector molecules of the innate immunity that possess antimicrobial and health-promoting properties. Due to their potential therapeutic activities, host defense peptides are being explored as alternatives for antibiotics. The human LL-37 and its shorter, cost-effective, bactericidal core peptide derivates have been suggested for their therapeutic potential. Bacteria evade host defense peptides by proteolytic inactivation. Actin released from necrotized cells and abundant in infected sites was shown to bind and protect LL-37 from microbial proteolytic degradation, and to enable the peptide's antimicrobial action despite the presence of the proteases. Here, we characterized the interactions of the 10–13 residues long LL-37 core peptides with actin. We show that the LL-37 core peptides associate with actin with a lower affinity than that of LL-37. Their association with actin, which is very ionic strength sensitive, is mainly based on electrostatic interactions. Likewise, the antimicrobial activity against Escherichia coli of the minimal antimicrobial peptide KR-12 but not FK-13 nor LL-37 is also very sensitive to salts. In addition, the antimicrobial activity of the FK-13 core peptide is protected by actin against the tested bacterial proteases in a similar manner to that of LL-37, supporting its potential for therapeutic use.
Interfacial peroxidase-like catalytic activity of surface-immobilized cobalt phthalocyanine on multiwall carbon nanotubesLi, Nan; Lu, Wangyang; Pei, Kemei; Chen, Wenxing
doi: 10.1039/c4ra15306epmid: N/A
The rapid diffusional mass transfer process (DMTP) always results in a highly efficient reaction. Herein, cobalt phthalocyanine (CoPc) was covalently anchored on to multiwall carbon nanotubes (MWCNTs) by an easy and moderate one-step deamination method to obtain the catalyst MWCNT-immobilized CoPc (CoPc-MWCNT). The interfacial peroxidase-like catalytic activity of CoPc-MWCNTs is described for controllable H2O2 activation. According to the experimental results and density functional theory calculations, we can be confident that high-valent cobalt-oxo intermediates are formed during the H2O2 activation. Such active species are anchored and exposed on the surface of MWCNTs, shortening the DMTP and enhancing the resistance of CoPc-MWCNTs to oxidative decay. The introduction of linear alkylbenzene sulphonates (LAS) facilitates the catalytic H2O2 activation by CoPc-MWCNTs, and at the same time, CoPc-MWCNTs could maintain a high and sustained catalytic activity because of the specific hydrophobic interactions between the long-chain alkyl group of LAS and the π-conjugated surface of the MWCNTs.
Modulated photophysics and rotational-relaxation dynamics of coumarin 153 in nonionic micelles: the role of headgroup size and tail length of the surfactantsPaul, Bijan K.; Ghosh, Narayani; Mukherjee, Saptarshi
doi: 10.1039/c4ra12568apmid: N/A
Here, the effect of variation in the headgroup size and the alkyl tail length of nonionic surfactants on the photophysics and rotational-relaxation dynamics of the laser dye coumarin 153 (C153) has been explored. The variation in the headgroup size, that is, poly(ethylene oxide) (PEO) chain length of the nonionic micellar systems, has been implemented using a variety of surfactants belonging to Triton X family, whereas surfactants from the Tween family provides an access to the variation of the tail length (alkyl chain) of the surfactants. Our spectroscopic study reveals a remarkable influence on the photophysics of C153 upon binding with the micelles. The strength of the dye-micelle binding interaction is found to be largely controlled by the variation of the headgroup size and the length of the tail of the surfactants. To this end, the dye-micelle binding interaction has been quantitatively assayed from emission studies and carefully interpreted based on the micellar hydration model. The estimation of the micropolarity of the dye binding site is further employed to corroborate this argument. Furthermore, all these line of arguments are effectively substantiated from time-resolved fluorescence experiments with particular emphasis on the modulation of rotational dynamics of the dye within the micellar micro-heterogeneous environments.