A quantitative method to assess the role of indoor air decontamination to simultaneously reduce contamination of environmental surfaces: testing with vegetative and spore-forming bacteria.

Indoor air can spread pathogens, which can be removed/inactivated by a variety of means in healthcare and other settings. We quantitatively assessed if air decontamination could also simultaneously reduce environmental surface contamination in the same setting. Two types of vegetative bacteria (Staphylococcus aureus and Acinetobacter baumannii), and a bacterial spore-former (Geobacillus stearothermophilus) were tested as representative airborne bacteria. They were separately aerosolized with a Collison nebulizer into a 24-m3 aerobiology chamber and air samples collected with a programmable slit-to-agar sampler. Settling airborne particles were collected on culture plates placed at, and collected from, five different locations on the floor of the chamber with a custom-built remote plate-placement and -retriever system. Experimentally contaminated air in the chamber was decontaminated for 45 min with a device based on HEPA filtration and UV light. The plates were incubated and CFU counted. The device reduced the viability levels of all tested bacteria in the air by >3 log10 (>99·9%) in 45 min. Based on two separate tests, the average reductions in surface contamination for S. aureus, A. baumannii and G. stearothermophilus were respectively, 97, 87 and 97%. We thus showed that air decontamination could substantially and simultaneously reduce the levels of surface contamination in the same setting irrespective of the type of pathogen present. SIGNIFICANCE AND IMPACT OF THE STUDY: The innovative and generic test protocol described can quantitatively assess the reduction in environmental surface contamination from microbial decontamination of indoor air in the same setting. This added advantage from air decontamination has implications for infection prevention and control in healthcare and other settings without the need for additional expense or effort. Continuous operation of an air decontamination device, such as the one tested here, can lead to ongoing reductions in pathogens in air and on environmental surfaces.

Colorimetric determination of resorcinol based on localized surface plasmon resonance of silver nanoparticles.

In this paper, we have developed a simple colorimetric method for detection of resorcinol (RE); the method is based on the reaction of RE with silver ions (oxidizing agent) in the presence of starch as a stabilizer and formation of silver nanoparticles (AgNPs). At nanometer dimensions the electron cloud can oscillate on the particle surfaces when dispersed in liquid media so these nanoparticles exhibit a strong UV-Vis extinction band. A UV-Vis spectrophotometer is used to monitor the changes of the localized surface plasmon resonance (LSPR) of AgNPs at a wavelength of 430 nm. There is a linear relationship between absorbance intensity of AgNPs and the concentration of RE over the range of 4 × 10(-6) to 1.1 × 10(-5) mol L(-1) at 430 nm. The detection limit was 1.2 × 10(-6) mol L(-1). The proposed method has been successfully applied for the determination of RE in anti-acne solution and spiked shampoo samples.

Fast and efficient removal of mercury from water samples using magnetic iron oxide nanoparticles modified with 2-mercaptobenzothiazole.

Mercury in the lowest levels of concentrations is dangerous for human health due to its bioaccumulation in body and toxicity. This investigation shows the effective removal of mercury (II) ions from contaminated surface waters by modified magnetic iron oxide nanoparticles (M-MIONPs) with 2-mercaptobenzothiazole as an efficient adsorbent. The proposed method is fast, simple, cheap, effective and safe for treatment of mercury polluted waters. Preparation of adsorbent is easy and removal time is short. Non-modified magnetic iron oxide nanoparticles (MIONPs) can adsorb up to 43.47% of 50 ngmL(-1) of Hg (II) ions from polluted water, but modified magnetic ironoxide nanoparticles (M-MIONPs) improved the efficiency up to 98.6% for the same concentration. The required time for complete removal of mercury ions was 4 min. Variation of pH and high electrolyte concentration (NaCl) of the solution do not have considerable effect on the mercury removal efficiency. Loading capacity of adsorbent for Hg ions is obtained to be 590 µgg(-1).

Fast removal and recovery of amaranth by modified iron oxide magnetic nanoparticles.

The adsorption and removal of amaranth (AM) from an aqueous solution by iron oxide nanoparticles (IONPs) coated with cetyltrimethylammonium bromide (CTAB) as adsorbent was reported. The novel magnetic separation was quite efficient for the adsorption and desorption of AM. In an aqueous solution of AM at 25 degrees C, the adsorption data could be fitted by the Langmuir equation with a maximum adsorption amount of 1.05 mg mg(-1) and a Langmuir adsorption equilibrium constant of 0.90 Lmg(-1). The effect of temperature, pH of aqueous medium, electrolyte concentration, composition of desorbent solvent and interfering ions on the recovery process were also investigated. Methanol was used for desorption of adsorbed AM. Due to the absence of internal diffusion resistance both adsorption and desorption of AM were fast and could be completed within 5 min. The results indicated that the CTAB-coated IONPs could be employed in the removal of the anionic dye from wastewater. The AM was removed successfully in spiked samples of Karoon River water.

Modified iron oxide nanoparticles as solid phase extractor for spectrophotometeric determination and separation of basic fuchsin.

This study presents a novel separation, preconcentration and determination of basic fuchsin (BF) in an aqueous solution by sodium dodecyl sulfate (SDS)-bounded iron oxide nanoparticles (S-IONPs). It is shown that the novel magnetic nano-adsorbent is quite efficient for the adsorption and desorption of BF at 25 degrees C. Different parameters such as pH, temperature, ionic strength and composition of desorbent solvent were optimized. The effect of some co-existing ions on the determination was investigated. The nanoparticles were analyzed by transmission electron microscopy (TEM) and the sizes of S-IONPs were in the range of 20-100 nm. The method showed good linearity for the determination of BF in the range of 10-300 ng mL(-1) with a regression coefficient of 0.9989. The limit of detection (LOD) (signal-to-noise ratio of 3:1) was 0.0073 microg L(-1) and the relative standard deviation (RSD) for 0.03 microg mL(-1) and 0.2 microg mL(-1) of BF were 4.53% and 4.73%, respectively. The BF was determined successfully in spiked samples of Karoon River water.

Determination of isosorbide dinitrate in arterial plasma, synthetic serum and pharmaceutical formulations by linear sweep voltammetry on a gold electrode.

Isosorbide dinitrate (ISDN) is reduced voltammetrically at gold working electrode surface in aqueous sodium sulfite solution and produces a voltammogram with its peak current proportional to the concentration of ISDN in the range of 1.3-2340 mug ml(-1). Sodium sulfite is used as supporting electrolyte and oxygen removing agent and, therefore, no nitrogen gas purging for elimination of soluble oxygen in, the sample solution is required. The limit of detection (LOD) of the method is 0.0838 mug ml(-1) and the relative standard deviation (R.S.D.) of 24 replicate determination of 52 mug ml(-1) of ISDN is 3.60%. The method is used for quantitative analysis of ISDN in arterial plasma, synthetic serum and pharmaceutical dosage form. The results are compared with those obtained from GC determination method. The method is sensitive and requires little sample preparation in a wide concentration range.