Abstract: A method to make metal-organic frameworks (MOFs) in which a first aqueous solution of a transition metal salt is mixed with a second aqueous solution of an imidazole or alkyl-substituted imidazole to yield a product solution containing MOF crystals. The MOF crystals are used to fabricate electrodes for electrochemical detection of nitro-aromatic compounds.

Abstract: Nanoreactors comprising a metal precursor in a carrier are provided as well as methods of initiating, methods of preparing, and methods of using nanoreactors. In some embodiments, upon exposure to heat, the metal precursor forms nanoparticles that can be detected, e.g., by detecting a color change in the nanoreactor and/or by detecting the number and/or size and/or size distribution and/or shape of the nanoparticles. The nanoreactors can be used, in some embodiments, as time-temperature indicators for perishable goods.

Abstract: Described is a system and corresponding method for remediating liquid waste streams. The system includes an electro-oxidation (EO) chamber, an electro-deposition (ED) chamber, and an electro-adsorption (EA) chamber. In the method, a waste stream is subjected to electro-oxidation, followed by electro-deposition and/or electro-adsorption. The method removes both organic and inorganic pollutants, as well as metals present as free ions or bound into organic or inorganic complexes.

Abstract: A method to make free-standing graphene sheets and the free-standing graphene sheets so formed. The method includes the steps of exfoliating partially oxidized graphene from a carbon-containing electrode into an aqueous solution, acidifying the aqueous solution, and separating from the acidified solution partially oxidized graphene sheet. The partially oxidized graphene is then dried to yield free-standing graphene sheet having a carbon-to-oxygen ratio of at least about 8.0.

Abstract: Composite nanofibers comprising polymers and tannins, methods of making same, and methods of use. The nanofibers include a polymer, such as a synthetic polymer, and a tannin. The tannin can include condensed tannins (proanthocyanidins) and/or hydrolyzable tannins. The nanofibers exhibit a number of structural and functional characteristics, such as enhanced swelling in aqueous liquid, enhanced antibacterial activity, enhanced bacterial adsorption, enhanced fibroblast adhesion, enhanced fibroblast proliferation, and enhanced surface coating of silver nanoparticles, among others. The nanofibers can be made by electrospinning a solvent mixture comprising the synthetic polymer and the tannin in a solvent. The nanofibers can be used in methods of isolating cells, methods of filtration, and methods of detecting cells, among others.

Abstract: A method to make metal-organic frameworks (MOFs) in which a first aqueous solution of a transition metal salt is mixed with a second aqueous solution of an imidazole or alkyl-substituted imidazole to yield a product solution containing MOF crystals. The MOF crystals are used to fabricate electrodes for electrochemical detection of nitro-aromatic compounds.

Abstract: A method to make metal-organic frameworks (MOFs) in which a first aqueous solution of a transition metal salt is mixed with a second aqueous solution of an imidazole or alkyl-substituted imidazole to yield a product solution containing MOF crystals. The MOF crystals are used to fabricate electrodes for electrochemical detection of nitro-aromatic compounds.

Abstract: Monodispersed colloidal gold nanoparticles (AuNPs) were synthesized by an easy, cost-effective, and eco-friendly synthesis route. The resulting AuNPs exhibited excellent electroanalytical ability to simultaneously detect toxic As(III) and As(V). The limit of quantification (LOQ) toward As(III) was 0.075 ppb (1 nM), which is well below the guideline value approved by the United States Environmental Protection Agency (US EPA) and the World Health Organization (WHO). Under the optimal conditions, a linear response in the concentration range of from about 0.075 ppb to about 0.03 ppm (1 nM-400 nM) was observed. The method is useful to detect arsenic contamination of water intended for human and animal consumption.

Abstract: Nanoreactors having a metal precursor in a carrier are provided. In some embodiments, upon exposure to heat, the metal precursor forms nanoparticles that can be detected, e.g., by detecting a color change in the nanoreactor and/or by detecting the number and/or size and/or size distribution and/or shape of the nanoparticles. The nanoreactors can be used, in some embodiments, as time-temperature indicators for perishable goods.

Abstract: Nanoreactors comprising a metal precursor in a carrier are provided as well as methods of initiating, methods of preparing, and methods of using nanoreactors. In some embodiments, upon exposure to heat, the metal precursor forms nanoparticles that can be detected, e.g., by detecting a color change in the nanoreactor and/or by detecting the number and/or size and/or size distribution and/or shape of the nanoparticles. The nanoreactors can be used, in some embodiments, as time-temperature indicators for perishable goods.

Abstract: A device for measuring pH levels and contaminant concentration includes an electrode assembly that is electrically coupled to a control unit. The electrode assembly includes a first contact electrically coupled to a reference electrode, a second contact electrically coupled to a working electrode, and a third contact electrically coupled to a counter electrode. The working electrode may be modified to include a cysteine functionalized graphene oxide with polypyrrole nanocomposite. In operation, the control unit may apply a complex signal to the working electrode via the second contact in order to adhere and subsequently strip contaminant ions from the fluid sample to the working electrode. During this process, a current may be measured across the working electrode and the counter electrode to measure contaminant ion concentration. The pH of the fluid sample may also be determined by a current measured across the reference electrode and the counter electrode.

Abstract: Described are carbon nanotube dispersions containing single-walled carbon nanotubes dispersed in a dispersant solution comprising a solvent (water, organic polar protic solvents, and/or organic polar aprotic solvents), and an azo compound. The single-walled carbon nanotubes are not cross-linked with covalent bonds. The dispersions are useful for fabricating transparent conductive thin films on flexible and inflexible substrates. Methods for making the transparent conductive thin films are also described.

Abstract: Nanoreactors comprising a metal precursor in a carrier are provided as well as methods of initiating, methods of preparing, and methods of using nanoreactors. In some embodiments, upon exposure to heat, the metal precursor forms nanoparticles that can be detected, e.g., by detecting a color change in the nanoreactor and/or by detecting the number and/or size and/or size distribution and/or shape of the nanoparticles. The nanoreactors can be used, in some embodiments, as time-temperature indicators for perishable goods.

Abstract: A method to make free-standing graphene sheets and the free-standing graphene sheets so formed. The method includes the steps of exfoliating partially oxidized graphene from a carbon-containing electrode into an aqueous solution, acidifying the aqueous solution, and separating from the acidified solution partially oxidized graphene sheet. The partially oxidized graphene is then dried to yield free-standing graphene sheet having a carbon-to-oxygen ratio of at least about 8.0.

Abstract: A method to make metal-organic frameworks (MOFs) in which a first aqueous solution of a transition metal salt is mixed with a second aqueous solution of an imidazole or alkyl-substituted imidazole to yield a product solution containing MOF crystals. The MOF crystals are used to fabricate electrodes for electrochemical detection of nitro-aromatic compounds.

Abstract: Methods of detecting very low levels of targets, such as cells, are provided. In some embodiments, for example, the methods can detect bacteria present in a sample at concentrations less than 25 cells/mL. The method involves detecting nanoparticle aggregation in the absence of the target.

Abstract: Nanoreactors comprising a metal precursor in a carrier are provided. In some embodiments, upon exposure to heat, the metal precursor forms nanoparticles that can be detected, e.g., by detecting a color change in the nanoreactor and/or by detecting the number and/or size and/or size distribution and/or shape of the nanoparticles. The nanoreactors can be used, in some embodiments, as time-temperature indicators for perishable goods.

Abstract: Methods of detecting very low levels of targets, such as cells, are provided. In some embodiments, for example, the methods can detect bacteria present in a sample at concentrations less than 25 cells/mL. The method involves detecting nanoparticle aggregation in the absence of the target.

Abstract: A device for measuring pH levels and contaminant concentration includes an electrode assembly that is electrically coupled to a control unit. The electrode assembly includes a FLUID first contact electrically coupled to a reference electrode, a second contact electrically coupled to a working electrode, and a third contact electrically coupled to a counter electrode. The working electrode may be modified to include a cysteine functionalized graphene oxide with polypyrrole nanocomposite. In operation, the control unit may apply a complex signal to the working electrode via the second contact in order to adhere and subsequently strip contaminant ions from the fluid sample to the working electrode. During this process, a current may be measured across the reference electrode and the counter electrode to measure contaminant ion concentration. The pH of the fluid sample may also be determined by a current measured across the reference electrode and the counter electrode.

Abstract: Described are carbon nanotube dispersions containing single-walled carbon nanotubes dispersed in a dispersant solution comprising a solvent (water, organic polar protic solvents, and/or organic polar aprotic solvents), and an azo compound. The single-walled carbon nanotubes are not cross-linked with covalent bonds. The dispersions are useful for fabricating transparent conductive thin films on flexible and inflexible substrates. Methods for making the transparent conductive thin films are also described.