A highly sensitive aptasensor towards Plasmodium lactate dehydrogenase for the diagnosis of malaria

Finding a highly sensitive diagnostic technique for malaria has challenged scientists for the last century. In the present study, we identified versatile single-strand DNA aptamers for Plasmodium lactate dehydrogenase (pLDH), a biomarker for malaria, via the Systematic Evolution of Ligands by EXponential enrichment (SELEX). The pLDH aptamers selectively bound to the target proteins with high sensitivity (K(d)=16.8-49.6 nM). The selected aptamers were characterized using an electrophoretic mobility shift assay, a quartz crystal microbalance, a fluorescence assay, and circular dichroism spectroscopy. We also designed a simple aptasensor using electrochemical impedance spectroscopy; both Plasmodium vivax LDH and Plasmodium falciparum LDH were selectively detected with a detection limit of 1 pM. Furthermore, the pLDH aptasensor clearly distinguished between malaria-positive blood samples of two major species (P. vivax and P. falciparum) and a negative control, indicating that it may be a useful tool for the diagnosis, monitoring, and surveillance of malaria.     

Cationic Surfactant-Based Colorimetric Detection of Plasmodium Lactate Dehydrogenase,a Biomarker for Malaria,Using the Specific DNA Aptamer

A simple, sensitive, and selective colorimetric biosensor for the detection of the malarial biomarkers Plasmodium vivax lactate dehydrogenase (PvLDH) and Plasmodium falciparum LDH (PfLDH) was demonstrated using the pL1 aptamer as the recognition element and gold nanoparticles (AuNPs) as probes. The proposed method is based on the aggregation of AuNPs using hexadecyltrimethylammonium bromide (CTAB). The AuNPs exhibited a sensitive color change from red to blue, which could be seen directly with the naked eye and was monitored using UV-visible absorption spectroscopy and transmission electron microscopy (TEM). The reaction conditions were optimized to obtain the maximum color intensity. PvLDH and PfLDH were discernible with a detection limit of 1.25 pM and 2.94 pM, respectively. The applicability of the proposed biosensor was also examined in commercially available human serum.     

Comparison of Trophic Modes to Maximize Biomass and Lipid Productivity of <Emphasis Type="Italic">Micractinium inermum</Emphasis> NLP-F014

An optimum trophic mode condition was investigated to maximize biomass and lipid productivity of Micractinium inermum NLP-F014, which grown successfully in blended wastewater medium. In this study, four trophic modes were used, including photoautotrophic, photoheterotrophic, heterotrophic and mixotrophic modes. Mixotrophic mode showed the highest biomass and lipid productivity. However, a high concentration of organics resulted the negative effect on the growth of M. inermum NLP-F014. Mixotrophic cultivation using glucose below 500 mg/L was able to produce maximum biomass productivity up to 0.90 ± 0.03 g/L/day as well as maximum lipid productivity up to 129.31 ± 0.10 mg/L/day. From lipid analysis on mixotrophic mode using glucose, the major fatty acids are oleic acid (C18:1), linoleic acid (C18:2) and palmitic acid (C16:0). These results suggest that mixotrophic mode cultivation with wastewater containing chemical oxygen demand (COD) below 500 mg/L could be applicable for biodiesel production of M. inermum NLP-F014.     

Detection of the strand exchange reaction using DNAzyme and Thermotoga maritima recombinase A

We have designed multiple detection systems for the DNA strand exchange process. Thermostable Thermotoga maritima recombinase A (TmRecA), a core protein in homologous recombination, and DNAzyme, a catalytic DNA that can cleave a specific DNA sequence, are introduced in this work. In a colorimetric method, gold nanoparticles (AuNPs) modified with complementary DNAs (cDNAs) were assembled by annealing. Aggregated AuNPs were then separated irreversibly by TmRecA and DNAzyme, leading to a distinct color change in the particles from purple to red. For the case of fluorometric detection, fluorescein isothiocyanate (FITC)-labeled DNA as a fluorophore and black hole quencher 1 (BHQ1)-labeled DNA as a quencher were used; successful strand exchange was clearly detected by variations in fluorescence intensity. In addition, alterations in the impedance of a gold electrode with immobilized DNA were employed to monitor the regular exchange of DNA strands. All three methods provided sufficient evidence of efficient strand exchange reactions and have great potential for applications in the monitoring of recombination, discovery of new DNAzymes, detection of DNAzymes, and measurement of other protein activities.     

The potential of a natural biopolymeric flocculant, ε-poly-l-lysine,for harvesting Chlorella ellipsoidea and its sustainability perspectives for cost and toxicity

Bioprocess and Biosystems Engineering - The successful production of microalgal biomass requires the precise coordination of many different steps. Cell harvesting is a central process in all...     

Bacterial production and structure-functional validation of a recombinant antigen-binding fragment (Fab) of an anti-cancer therapeutic antibody targeting epidermal growth factor receptor

Applied Microbiology and Biotechnology - Fragment engineering of monoclonal antibodies (mAbs) has emerged as an excellent paradigm to develop highly efficient therapeutic and/or diagnostic agents....