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The objective of our study was to explore novel interactions that can be helpful in the self-assembly of polydimethyl siloxane (PDMS) macro-objects. In this approach, ionic self-assembly of polydiallyldimethylammonium chloride (PDDA) and deoxyguanosine monophosphate (dGMP) molecules were utilized for layer-by-layer (LbL) assembly with an exposed layer of dGMP. Moreover, the assembly-disassembly process was more thoroughly understood by force measurement analysis in different solvents by using a tensiometer instrument. This study will open up the gate for the utilization of further forces to assemble macro-objects by mimicking this approach., {"references":["[1]\tC. F. Faul, \"Ionic self-assembly for functional hierarchical nanostructured materials,\" Accounts of chemical research, vol. 47, no. 12, pp. 3428-3438, 2014. [2]\tI. Manasi, M. R. Andalibi, R. S. Atri, J. Hooton, S. M. King, and K. J. 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A single step fast track method is proposed to determine melamine based on strong hydrogen bonding between exocyclic amine group in melamine moiety and hydroxyl group of tannic acid (TA); acting as reducing and functionalizing agent for synthesis of gold nanoparticles (Au NPs). The proposed strategy is facile and highly time saving; as the detection of melamine with labelfree gold nanoparticles was accomplished within five minutes. The colorimetric probe exhibits high detection limit of 8 nM for melamine determination in raw milk, which is very low as compared to other capping ligands employed for Au NPs such as borohydride, citrate and 3,5-dihydroxybenzoic acid. The results show a highly sensitive linear range (0.03–2.5 μM) between absorption ratio and concentration of melamine with a correlation coefficient of 0.991. Proposed methodology is proven effective for on-site screening without using costly instrumentation.

It is known that the localized surface plasmon resonance (LSPR) wavelength of plasmonics is highly dependent on compositions and geometry of plasmonics as well as the surrounding environments. Here, monodispersed Au@Ag core-shell nanoparticles (Au@Ag NPs) were prepared by carefully optimizing the shell thickness of Au@Ag NPs, and the presence of hydrogen sulfide (H2S) would significantly alter the LSPR wavelength. On the basis of this, a photothermal paper sensor for on-site recognition of H2S was constructed with a visual detection limit of 12.8 ng/L.

In this study, we report a novel and facile autoclave strategy for synthesis of near-infrared (NIR) CuInS2 QDs by employing glutathione (GSH) as capping ligand and stabilizer in aqueous media under 100°C. Various experimental parameters including the ratio of precursors, reaction time, reaction temperature, pH effect and stability have been systematically studied. The QDs were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The as-synthesized NIR QDs exhibited low cytotoxicity and maintained excellent cell viability even up to 100 µg/mL. After bioconjugation with Arg-Gly-Asp (RGD) peptide, the obtained CuInS2-RGD QDs have demonstrated high targeting ability with good fluorescence cell imaging performance.

We successfully fabricated 19F magnetic resonance imaging (MRI) nanoprobes by partly replacing the 2-methylimidazolate of the metal organic framework (MOF) matrix ZIF-8, of which the strong 19F MRI signal displays an interesting pH dependence property, indicating its great potential as a 19F MRI contrast agent for stimuli-responsive imaging with high penetration depth and low background.

A hierarchical excavated iron-nitrogen codoped mesoporous carbon (Ex-FeN-MC) electrocatalyst has been successfully synthesized by pyrolysis of the unique ureidopyrimidinone containing organic precursor MAMIS by using silica as the mesoporous template and iron nitrate as the source of iron. The selected organic precursor has multifunctionalities with diverse distribution of nitrogen and oxygen species which constitute interesting features to prepare the Ex-FeN-MC electrocatalyst. The as-prepared Ex-FeN-MC material shows unexpectedly higher catalytic activities towards ORR/OER performances with an overpotential of 250 mV for OER in alkaline solution at a current density of 10 mA cm−2, while the ORR activity is almost similar to that of commercial Pt/C. It is believed that the excellent electrochemical performance results from the synergic contribution of the hierarchical uniform mesoporous structure, evenly distributed iron nanoparticles and high density of Ex-FeN-MC catalytically active sites. The presence of the hierarchical uniform mesoporous structure considerably accelerates the mass transfer and efficiently promotes the full utilization of active sites. Furthermore, it also possesses amorphous carbon in coexistence with lattice graphitic carbon which also enhanced the ORR/OER performances. Our research findings can surely provide a new insight to design highly active ORR/OER electrocatalysts by utilizing more novel organic precursors to provide interesting characteristics to electrocatalysts, as well as open up a route for constructing unique multifunctional materials with mesoporous architectures for electrocatalysis and supercapacitor applications.

Rapid, reliable, onsite approaches for detection trace level of trinitrotoluene (TNT) is a pressing necessity for both homeland security and environmental protection. To this end, hydrophilic amine(-NH2) protected Au@Ag nanoparticles (NPs) were developed and fabricated as colorimetric paper sensor for delicate detection of TNT. The as-developed nanoprobe selectively reacts with TNT through classic Meisenheimer complex formation by means of charge transfer process from an electron-rich NH2 group of β-cysteamine to an electron-deficient nitro group on TNT. Due to the absence of this particular interaction of other nitroaromatics, the proposed probe is highly selective for TNT detection with a better linear range (0–20 μg/mL) and limit of detection (LOD) of 0.35 μg/mL. The present work provides a novel and facile strategy to fabricate colorimetric paper sensors with rapid and selective recognition ability for label free analysis of TNT.

Objective: Medicinal herbs have been widely explored due to their ability to scavenge free radicals and protect from the reactive oxygen species those are involved in several kinds of degenerative diseases. Glycyrrhiza glabra is a perennial herb, its extensive soft and fibrous root system is good source of nutrients and antioxidants applicable in different types of diseases and wide range of pharmacological activities including expectorant, antitussive, emollient, anti-inflammatory, antipyretic activities. This study aimed to determine the best combination of extraction media and techniques for the extraction of phenolic compounds from its roots for best utilization in medicinal applications. Methods: The extractions were carried out in methanol, chloroform and ether by using soxhlet, ambient and orbital shaker extraction techniques. The antioxidant activity of these extracts was also evaluated by determining crucial parameters, such as total phenolic contents, total flavonoid contents, DPPH radical scavenging activity and estimation of antioxidant activity in linoliec acid system. Results: We have found that all extraction techniques exhibited a wide range of total phenolic, 9.689 ± 1.015 to 56.7 ± 5.935 mg/g of gallic acid equivalents and total flavonoid content, 9.6153 ± 0.985 to 53.77 ± 4.29 mg/g of quercitin equivalents. In addition, these extraction techniques also inhibited oxidation of linoleic acid by 45.113 ± 2.567 % to 88.516 ± 2.188 % , while DPPH radical scavenging activity in the range of to 7.706 ± 0.258 % to 92.627 ± 3.0 %. Moreover, soxhlet extraction technique showed the highest recovery of TPC and maximum AA content, while orbital shaker extraction technique showed the highest DPPH scavenging activity. The extraction efficiency of antioxidant compounds was highest in methanol. Conclusions: Analysis of the TPC, TFC and free radical scavenging activity of Glycyrrhiza glabra extracts showed differences depending on extraction method and solvent used. Among the tested parameters, more polar solvent with soxhlet extraction is recommended for the extraction of antioxidants from roots of Glycyrrhiza glabra.