Application of the catalytic activity of gold nanoparticles for development of optical aptasensors.

Biosensor technology is considered to be a great alternative in analytical techniques over the conventional methods. Among many recently developed techniques and devices, aptasensors are interesting because of their high specificity, selectivity and sensitivity. Combining aptamer as a biological recognition element with gold nanoparticles (AuNPs) as probe, are becoming more general owing to their beneficial properties, including low cost and ability to analyze specific targets on-site and using naked eye. Hydrogen bonds, nucleic acid hybridization, aptamer-target and antigen-antibody binding, Raman signature, enzyme inhibition, and enzyme-mimicking activity are main different sensing strategies exploited in AuNPs-based optical aptasensors. In this review article, we discussed the recent advances in optical aptasensors with a special emphasis on the catalytic activity property of AuNPs.

Aptamer-based ATP-responsive delivery systems for cancer diagnosis and treatment.

In recent years, many stimuli-triggered drug delivery platforms have been designed to deliver drugs accurately to specific sites and reduce their side effects, improving "on-demand" therapeutic efficacy. Adenosine-5'-triphosphate (ATP)-responsive drug delivery methods are examples of these systems that use ATP molecules as a trigger for delivery of therapeutic agents. Since intra- and extra-cellular ATP concentrations are significantly different from each other (1-10 mM and <0.4 mM, respectively), the use of ATP can be a practical method for regulating drug release. Aptamers possess unique properties including, ligand-specific response, short sequence (~ 20-80 bases) and easy functionalization. Thus, their combination with ATP-responsive systems results in more accurate drug delivery systems and greater control of drug release. A wide range of nanoparticles, such as polymeric nanogels, liposomes, metallic nanoparticles, protein, or DNA nano-assemblies, have been employed in the fabrication of nanocarriers. In this review, we describe several ATP-responsive drug delivery systems based on the various carriers and discuss the challenges and strengths of each method.

The effects of Crataegus pinnatifida (Chinese hawthorn) on metabolic syndrome: A review.

Metabolic syndrome is described as a group of risk factors in which at least three unhealthy medical conditions, including obesity, high blood sugar, hypertension or dyslipidemia occur simultaneously in a patient. These conditions raise the risk for diabetes mellitus and cardiovascular diseases. Many recent studies have focused on herbal remedies and their pharmacological effects on metabolic syndrome. Crataegus pinnatifida or Chinese hawthorn has been widely used in the treatment of hyperlipidemia and cardiovascular diseases. Its leaves, fruits and seeds have various active substances such as, flavonoids, triterpenic acids and sesquiterpenes, which through different mechanisms can be beneficial in metabolic syndrome. Flavonoids found in the leaves of hawthorn can significantly reduce atherosclerotic lesion areas, the fruit extracts contain two triterpenic acids (oleanolic acid and ursolic acid), that have the ability to inhibit the acyl-coA-cholesterol acyltransferase (ACAT) enzyme and as a result reduce very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) cholesterol levels. Another example regards a sesquiterpene found in the seeds of C. pinnatifida, which exhibits the ability to inhibit platelet aggregation, thus showing antithrombotic activity. Various studies have shown that C. pinnatifida can have beneficial effects on controlling and treating high blood sugar, dyslipidemia, obesity and atherosclerosis. The aim of this review is to highlight the interesting effects of C. pinnatifida on metabolic syndrome.

A label-free fluorescent aptasensor for detection of kanamycin based on dsDNA-capped mesoporous silica nanoparticles and Rhodamine B.

Kanamycin is an aminoglycoside antibiotic that can be useful against both gram negative and positive bacteria. However, if its serum levels are not controlled properly, it can cause serious side effects like ototoxicity and nephrotoxicity. The aim of this study was to design a simple and rapid fluorescent aptasensor for detection of kanamycin, based on Aptamer/Complementary strand (dsDNA)-capped mesoporous silica nanoparticles (MSNs) and Rhodamine B as a fluorescent probe. The MSNs pores were filled with Rhodamine B and then gated with dsDNA. In the presence of kanamycin, the aptamer sequence was separated from its complementary strand (CS), so that, uncovered the pores and leading to leakage of Rhodamine B. Thus, a significant increase in the fluorescence intensity was observed. The relative fluorescence intensity showed a linearity range from 24.75 nM to 137.15 nM of kanamycin with a detection limit of 7.5 nM. The aptasensor also showed to be useful for detection of kanamycin in serum samples and was able to distinguish kanamycin from other antibiotics, resulting in a sensitive, rapid and inexpensive method for kanamycin detection.