Single-stranded DNA aptamers were generated from a random library to remove arsenic from Vietnamese groundwater. On the basis of significant arsenic contamination levels, three areas in Ha Nam province (Vinh Tru, Bo De, and Hoa Hau) and five areas near the Mekong River Delta (MR1-5) were selected as study areas. The aptamers were in vitro selected using an arsenic aptamer affinity column created by immobilizing arsenic on Affi-gel 10 resin. Quantitative analyses of the aptamer candidates Ars-1 to Ars-8 by surface plasmon resonance (SPR) revealed the Ars-3 aptamer to have the highest affinity to arsenate [(As(V)] and arsenite [As(III)] with a dissociation constant (K(d)) of 4.95 +/- 0.31 and 7.05 +/- 0.91 nM, respectively. The specific affinity interactions of the Ars-3 aptamer to arsenic were verified against other heavy metals. After obtaining successful removal results with a laboratory-prepared aqueous arsenic solution, Ars-3 was applied for removal of any arsenic present in the groundwater samples collected from the studied areas in Vietnam. Field results were also successful: various arsenic concentrations ranging from 28.1 to 739.2 microg/L were completely removed after 5 min of incubation with the arsenic-binding aptamer Ars-3.

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Candida rugosa lipase was immobilized on amino-functionalized magnetic supports via cross-linked enzyme aggregates (CLEA) and used to enhance the enzymatic degradation of polycaprolactone (PCL). The maximum amounts of lipase immobilized on the magnetic beads using glutaraldehyde as a coupling agent were determined to be 33.7 mg/g of beads with an 81% recovery of activity after immobilization. Compared to the free enzyme, the immobilized lipase showed the optimum pH at 1 unit higher (pH 8.0) and also retained its enzymatic activity at higher temperatures. There was 62.9% retention of lipase activity after 30 consecutive reuses, indicating its stability and reusability in aqueous media. Moreover, the immobilized lipase maintained more than 80% of its initial activity during 30 days storage period, while the free lipase lost all under same condition. In addition, the immobilized lipase showed a more than 6-fold increase in biodegradability over the free lipase when the immobilized lipase was used to degrade PCL in a batch system. Higher thermal and storage stability, as well as good durability after repeated use of the immobilized lipase CLEA, highlights its potential applicability as large scale continuous systems for the enzymatic degradation of PCL.

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In this study, di-isononyl phthalate (DINP) was efficiently degraded by Sphingobium chungbukense KCTC 2955. The optimal conditions for DINP (100 mg L(-1)) degradation by S. chungbukense in a mineral salts medium were found to be pH 7.0, 30 degrees C, and stirring at 200 rpm. The maximum specific rate of DINP degradation was found to be concentration dependent, with a maximum of 4.12 mg DINP L(-1) h(-1). DINP was transformed rapidly by S. chungbukense, with the formation of monoisononyl phthalate (MIP) and phthalic acid, which subsequently degraded further. These results highlight the potential of this bacterium for removing DINP-contaminated waste in the environment.

We demonstrate an aptablotting assay method that involves direct and indirect aptabody recognition. Nanoscale single-stranded DNA aptamers against GST and DIG-tags are utilized as aptabodies (GST-2 and DIG-1, respectively), and the GST-2 aptabody binding site, or aptatope, as predicted by a MOE-docking simulation of the protein-aptamer complex, shows the interaction of the GST-2 aptabody at the catalytically active region. The aptabody-aptatope interaction was evaluated by an in vitro enzyme inhibitory analysis. The binding capacity of the GST-2 aptabody was assessed by dot-blot, EMSA and SDS-PAGE/electroblot analyses, and the results showed that the aptabodies interact with both the native mono-/dimeric form and the denatured GST form on a membrane. The use of aptabodies can overcome the obstacles of current immunoblot assays, and these molecules are easily assessable via ELISA systems. Moreover, the hybridization of aptabodies and antibodies (hybrid-aptablotting) may have considerable impacts on the design of bioassay platforms.