Graphene and Other Nanomaterial-Based Electrochemical Aptasensors

Electrochemical aptasensors, which are based on the specificity of aptamer-target recognition, with electrochemical transduction for analytical purposes have received particular attention due to their high sensitivity and selectivity, simple instrumentation, as well as low production cost. Aptamers are functional nucleic acids with specific and high affinity to their targets, similar to antibodies. However, they are completely selected in vitro in contrast to antibodies. Due to their stability, easy chemical modifications and proneness to nanostructured device construction, aptamer-based sensors have been incorporated in a variety of applications including electrochemical sensing devices. In recent years, the performance of aptasensors has been augmented by incorporating novel nanomaterials in the preparation of better electrochemical sensors. In this review, we summarize the recent trends in the use of nanomaterials for developing electrochemical aptasensors

Antimicrobial aptamers for detection and inhibition of microbial pathogen growth

Discovery of alternative sources of antimicrobial agents are essential in the ongoing battle against microbial pathogens. Legislative and scientific challenges considerably hinder the discovery and use of new antimicrobial drugs, and new approaches are in urgent demand. On the other hand, rapid, specific and sensitive detection of airborne pathogens is becoming increasingly critical for public health. In this respect affinity oligonucleotides, aptamers, provide unique opportunities for the development of nanotechnological solutions for such medical applications. In recent years, aptamers specifically recognizing microbial cells and viruses showed great potential in a range of analytical and therapeutic applications. This article describes the significant advances in the development of aptamers targeting specific pathogens. Therapeutic application of aptamers as neutralizing agents demonstrates great potential as a future source of antimicrobial agent

Magnetic Polymeric Beads Functionalized with Different Mixed-Mode Ligands for Reversible Immobilization of Trypsin

In this study, we describe a preparation of magnetic affinity support carrying different ligands for immobilization of trypsin via adsorption. The magnetic support was synthesized in the bead form using glycidylmethacrylate (GMA) and methylmethacrylate (MMA) monomers. Three different ligands (i.e., <i>p</i>-aminobenzoic acid, l-phenylalanine and <i>p</i>-aminobenzamidine,) were attached on the aminated magnetic beads surface via glutaraldhyde coupling. Specific surface area of the mp­(GMA/MMA) beads was found to be 21.4 m²/g. The maximum trypsin adsorption was observed at pH 7.0 for <i>p</i>-aminobenzoic acid and l-phenylalanine and at pH 8.0 for <i>p</i>-aminobenzamidine carrying ligand. The maximum amounts of the enzyme adsorbed on the <i>p</i>-aminobenzoic acid-, l-phenylalanine-, and <i>p</i>-aminobenzamidine-attached magnetic beads reached 99.6, 84.2, and 75.9 mg/g with an enzyme activity recovery of 69.4, 73.2, and 22.9%, respectively. The l-phenylalanine ligand-attached support displayed a higher activity recovery than those of the <i>p</i>-aminobenzoic acid- and the <i>p</i>-aminobenzamidine-attached magnetic beads. This carrier showed also very good storage and operational stability. Trypsin immobilized on <i>p</i>-aminobenzoic acid showed significant activity toward casein. Trypsin could be repeatedly adsorbed and desorbed with all of the ligand-attached beads without a noticeable loss in the adsorption capacity

Investigation of Fosfomycin and Chloramphenicol Susceptibility of Carbapenemase-Producing Klebsiella pneumoniae Strains

Objective: Antimicrobial resistance is one of the most mportant health problems of recent years. Multidrug-resistant Klebsiella pneumoniae strains have been causing serious problems in many countries including Turkey in recent years. Aim of this study was to detect molecular mechanisms behind the carbapenem resistance in carbapenem-resistant K. pneurnoniae strains isolated from rectal swab samples and investigate the susceptibility of two potentially alternative drugs, fosfornycin, and chloramphenicol

Investigation of lsepamicin, Chloramphenicol and Minocycline Sensitivity in Carbapenem-Resistant Enterobacteriaceae

Objective: In this study, we aimed to determine the resistance mechanisms of carbapenem-resistant Enterobacteriaceae (CRE), and evaluate the prospective alternative treatment options

Microbial community of soda Lake Van as obtained from direct and enriched water, sediment and fish samples

Soda lakes are saline and alkaline ecosystems that are considered to have existed since the first geological records of the world. These lakes support the growth of ecologically and economically important microorganisms due to their unique geochemistry. Microbiota members of lakes are valuable models to study the link between community structure and abiotic parameters such as pH and salinity. Lake Van is the largest endroheic lake and in this study, bacterial diversity of lake water, sediment, and pearl mullet (inci kefali; Alburnus tarichi), an endemic species of fish which are collected from different points of the lake, are studied directly and investigated meticulously using a metabarcoding approach after pre-enrichment. Bacterial community structures were identified using Next Generation Sequencing of the 16S rRNA gene. The analysis revealed that the samples of Lake Van contain high level of bacterial diversity. Direct water samples were dominated by Proteobacteria, Cyanobacteria, and Bacteroidota, on the other hand, pre-enriched water samples were dominated by Proteobacteria and Firmicutes at phylum-level. In direct sediment samples Proteobacteria, whereas in pre-enriched sediment samples Firmicutes and Proteobacteria were determined at highest level. Pre-enriched fish samples were dominated by Proteobacteria and Firmicutes at phylum-level. In this study, microbiota members of Lake Van were identified by taxonomic analysis

Aptamer-Gated Nanoparticles for Smart Drug Delivery

Aptamers are functional nucleic acid sequences which can bind specific targets. An artificial combinatorial methodology can identify aptamer sequences for any target molecule, from ions to whole cells. Drug delivery systems seek to increase efficacy and reduce side-effects by concentrating the therapeutic agents at specific disease sites in the body. This is generally achieved by specific targeting of inactivated drug molecules. Aptamers which can bind to various cancer cell types selectively and with high affinity have been exploited in a variety of drug delivery systems for therapeutic purposes. Recent progress in selection of cell-specific aptamers has provided new opportunities in targeted drug delivery. Especially functionalization of nanoparticles with such aptamers has drawn major attention in the biosensor and biomedical areas. Moreover, nucleic acids are recognized as an attractive building materials in nanomachines because of their unique molecular recognition properties and structural features. A active controlled delivery of drugs once targeted to a disease site is a major research challenge. Stimuli-responsive gating is one way of achieving controlled release of nanoparticle cargoes. Recent reports incorporate the structural properties of aptamers in controlled release systems of drug delivering nanoparticles. In this review, the strategies for using functional nucleic acids in creating smart drug delivery devices will be explained. The main focus will be on aptamer-incorporated nanoparticle systems for drug delivery purposes in order to assess the future potential of aptamers in the therapeutic area. Special emphasis will be given to the very recent progress in controlled drug release based on molecular gating achieved with aptamers

Familial Mediterranean fever (FMF) in Turkey: results of a nationwide multicenter study

Familial Mediterranean fever (FMF) is an autosomal recessive disease that is prevalent among eastern Mediterranean populations, mainly non-Ashkenazi Jews, Armenians, Turks, and Arabs. Since a large proportion of all the FMF patients in the world live in Turkey, the Turkish FMF Study Group (FMF-TR) was founded to develop a patient registry database and analyze demographic, clinical, and genetic features. The cohort was composed of 2838 patients (mean age, 23.0 +/- 13.33 yr; range, 2-87 yr), with a male:female ratio of 1.2:1. There was a mean period of 6.9 +/- 7.65 years from disease onset to diagnosis; the period was about 2 years shorter for each decade since 1981. Ninety-four percent of patients were living in the central-western parts of the country; however, their familial origins (70% from the central-eastern and Black Sea regions) reflected not only the ongoing east to west migration, but also the historical roots of FMF in Turkey. Patients' clinical features included peritonitis (93.7%), fever (92.5%), arthritis (47.4%), pleuritis (31.2%), myalgia (39.6%), and erysipelas-like erythema (20.9%). Arthritis, arthralgia, myalgia, and erysipelas-like erythema were significantly more frequent (p < 0.001) among patients with disease onset before the age of 18 years. Genetic analysis of 1090 patients revealed that M694V was the most frequent mutation (51.4%), followed by M680I (14.4%) and V726A (8.6%). Patients with the M694V/M694V genotype were found to have an earlier age of onset and higher frequencies of arthritis and arthralgia compared with the other groups (both p < 0.001). In contrast to other reported studies, there was no correlation between amyloidosis and M694V homozygosity in this cohort. However, amyloidosis was still remarkably frequent in our patients (12.9%), and it was prevalent (27.8%) even among the 18 patients with a disease onset after age 40 years. Twenty-two patients (0.8%) had nonamyloid glomerular diseases. The high prevalence of vasculitides (0.9% for polyarteritis nodosa and 2.7% for Henoch-Schonlein purpura) and high frequency of pericarditis (1.4%) were striking findings in the cohort. Phenotype II cases (those patients with amyloidosis as the presenting or only manifestation of disease) were rare (0.3% or less). There was a high rate of a past diagnosis of acute rheumatic fever, which suggested a possible misdiagnosis in children with FMF presenting with recurrent arthritis. To our knowledge, this is the largest series of patients with FMF reported from 1 country. We describe the features of the disease in the Turkish population and show that amyloidosis is still a substantial problem