Engineered nanoparticles (ENPs) are known to possess unique size and shape dependent chemical and... more Engineered nanoparticles (ENPs) are known to possess unique size and shape dependent chemical and physical properties. As a result of their properties, ENPs have been effective in several important applications including catalysis, sensor design, photonics, electronics, medicine, and the environmental remediation of toxic pollutants. Such properties and applications have led to an increase in the manufacture of ENPs and a rise in their presence in consumer products. The increase of ENPs in consumer products presents several opportunities and challenges, and necessitates a proactive study of their health and safety. This article highlights some recent work in which we have studied the effect of exposure of well-defined ENPs to pesticides and the effect of pH and dissolved organic matter. We also summarize our work and that of others who have studied the toxicity of ENPs with microorganisms. The results provide insights on the need for green manufacturing strategies of ENPs, their use and safe disposal practices.
Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholineste... more Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more reactive phosphoryl (P=O) organophosphates, which include very lethal nerve agents and chemical warfare agents, such as, VX, Soman and Sarin. Unfortunately, widespread and frequent commercial use of OP-based compounds in agricultural lands has resulted in their presence as residues in crops, livestock, and poultry products and also led to their migration into aquifers. Thus, the design of new sensors with improved analyte selectivity and sensitivity is of paramount importance in this area. Herein, we review recent advances in the development of fluorescent chemosensors for toxic OP pesticides and related compounds. We also discuss challenges and progress towards the design of future chemosensors with dual modes for signal transduction.
We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nano... more We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nanoparticles (AuNP) were antimicrobial only when ampicillin was bound to their surfaces. Both AuNP and AgNP functionalized with ampicillin were effective broad-spectrum bactericides against Gram-negative and Gram-positive bacteria. Most importantly, when AuNP and AgNP were functionalized with ampicillin they became potent bactericidal agents with unique properties that subverted antibiotic resistance mechanisms of multiple-drug-resistant bacteria.
We have investigated the optical and electrochemical changes of the azastilbene, dimethyl-[4-(2-q... more We have investigated the optical and electrochemical changes of the azastilbene, dimethyl-[4-(2-quinolin-2-yl-vinyl)-phenyl]-amine (DQA), with four organothiophosphorus (OTP) pesticides: ethion, malathion, parathion, and fenthion. Significant changes in UV–visible absorbance wavelength and in electrochemical signals indicate the effectiveness of DQA as an OTP sensor.An azastilbene derivative 1 shows specific color changes when bound to either ethion, parathion, fenthion or malathion.
Engineered nanoparticles (ENPs) are known to possess unique size and shape dependent chemical and... more Engineered nanoparticles (ENPs) are known to possess unique size and shape dependent chemical and physical properties. As a result of their properties, ENPs have been effective in several important applications including catalysis, sensor design, photonics, electronics, medicine, and the environmental remediation of toxic pollutants. Such properties and applications have led to an increase in the manufacture of ENPs and a rise in their presence in consumer products. The increase of ENPs in consumer products presents several opportunities and challenges, and necessitates a proactive study of their health and safety. This article highlights some recent work in which we have studied the effect of exposure of well-defined ENPs to pesticides and the effect of pH and dissolved organic matter. We also summarize our work and that of others who have studied the toxicity of ENPs with microorganisms. The results provide insights on the need for green manufacturing strategies of ENPs, their use and safe disposal practices.
Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholineste... more Many organophosphorus (OP) based compounds are highly toxic and powerful inhibitors of cholinesterases that generate serious environmental and human health concerns. Organothiophosphates with a thiophosphoryl (P=S) functional group constitute a broad class of these widely used pesticides. They are related to the more reactive phosphoryl (P=O) organophosphates, which include very lethal nerve agents and chemical warfare agents, such as, VX, Soman and Sarin. Unfortunately, widespread and frequent commercial use of OP-based compounds in agricultural lands has resulted in their presence as residues in crops, livestock, and poultry products and also led to their migration into aquifers. Thus, the design of new sensors with improved analyte selectivity and sensitivity is of paramount importance in this area. Herein, we review recent advances in the development of fluorescent chemosensors for toxic OP pesticides and related compounds. We also discuss challenges and progress towards the design of future chemosensors with dual modes for signal transduction.
We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nano... more We show here that silver nanoparticles (AgNP) were intrinsically antibacterial, whereas gold nanoparticles (AuNP) were antimicrobial only when ampicillin was bound to their surfaces. Both AuNP and AgNP functionalized with ampicillin were effective broad-spectrum bactericides against Gram-negative and Gram-positive bacteria. Most importantly, when AuNP and AgNP were functionalized with ampicillin they became potent bactericidal agents with unique properties that subverted antibiotic resistance mechanisms of multiple-drug-resistant bacteria.
We have investigated the optical and electrochemical changes of the azastilbene, dimethyl-[4-(2-q... more We have investigated the optical and electrochemical changes of the azastilbene, dimethyl-[4-(2-quinolin-2-yl-vinyl)-phenyl]-amine (DQA), with four organothiophosphorus (OTP) pesticides: ethion, malathion, parathion, and fenthion. Significant changes in UV–visible absorbance wavelength and in electrochemical signals indicate the effectiveness of DQA as an OTP sensor.An azastilbene derivative 1 shows specific color changes when bound to either ethion, parathion, fenthion or malathion.
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