Green Synthesis of Silver Nanoparticles Using L. Aqueous Extract with the Evaluation of Its Antibacterial Activity against Clinical and Food Pathogens.

The rapid development of nanotechnology and its applications in medicine has provided the perfect solution against a wide range of different microbes, especially antibiotic-resistant ones. In this study, a one-step approach was used in preparing silver nanoparticles (AgNPs) by mixing silver nitrate with hot (St. John's wort) aqueous extract under high stirring to prevent agglomeration.

Identification of Major Constituents of L. Extracts in Syria by Development of a Rapid, Simple, and Reproducible HPLC-ESI-Q-TOF MS Analysis and Their Antioxidant Activities.

Linn () is a popular and widespread medicine in Syria, which is used for a wide range of conditions, including gastrointestinal diseases, heart disease, skin diseases, and psychological disorders. This widespread use prompted us to identify the main compounds of this plant from Syria that are responsible for its medicinal properties, especially since its components differ between countries according to the nature of the soil, climate, and altitude. This is, to the best of our knowledge, the first report in which , a plant native to Syria, is extracted using different solvents and its most important compounds are identified.

Aptamer-Modified Hydrogels.

Hydrogels have attracted much attention especially due to their biocompatibility and their potential for stimulus responsiveness. By combining hydrogels with aptamers, biological recognition and responsiveness can be added to hydrogels, thereby opening path to advanced applications in biosensing and biomedicine. Within this chapter aptamers will be introduced and their contributions to biological responsiveness of hydrogels will be described.

L.-Mediated Green Synthesis of Silver Nanoparticles Exhibiting Antioxidant and Anticancer Activities.

This contribution focuses on the green synthesis of silver nanoparticles (AgNPs) with a size < 100 nm for potential medical applications by using silver nitrate solution and L. (St John's wort) aqueous extracts. Various synthesis methods were used and compared with regard to their yield and quality of obtained AgNPs.

All-Optical Planar Polymer Waveguide-Based Biosensor Chip Designed for Smartphone-Assisted Detection of Vitamin D.

An all-optical plasmonic sensor platform designed for smartphones based on planar-optical waveguide structures integrated in a polymer chip is reported for the first time. To demonstrate the applicability of the sensor system for biosensing purposes, the detection of 25-hydroxyvitamin D (25OHD) in human serum samples using an AuNP-enhanced aptamer-based assay was demonstrated. With the aid of the developed assay sensitivity of 0.

Production of polycaprolactone nanoparticles with hydrodynamic diameters below 100 nm.

Cancer is a worldwide increasing burden and its therapy is often challenging and causes severe side effects in healthy tissue. If drugs are loaded into nanoparticles, side effects can be reduced, and efficiency can be increased via the enhanced permeability and retention effect. This effect is based on the fact that nanoparticles with sizes from 10 to 200 nm can accumulate in tumor tissue due to their leaky vasculature.

Aptamers vs. antibodies as capture probes in optical porous silicon biosensors.

Over the past decade aptamers have emerged as a promising class of bioreceptors for biosensing applications with significant advantages over conventional antibodies. However, experimental studies comparing aptasensors and immunosensors, under equivalent conditions, are limited and the results are inconclusive, in terms of benefits and limitations of each bioreceptor type. In the present work, the performance of aptamer and antibody bioreceptors for the detection of a his-tagged protein, used as a model target, is compared.

SPR Biosensor Based on Polymer Multi-Mode Optical Waveguide and Nanoparticle Signal Enhancement.

We present a surface plasmon resonance (SPR) biosensor that is based on a planar-optical multi-mode (MM) polymer waveguide structure applied for the detection of biomolecules in the lower nano-molar (nM) range. The basic sensor shows a sensitivity of 608.6 nm/RIU when exposed to refractive index changes with a measurement resolution of 4.

Development of Aptamer-Based TID Assays Using Thermophoresis and Microarrays.

Aptamers are single-stranded oligonucleotides which can be used as alternative recognition elements for protein detection, because aptamers bind their targets with a high affinity similar to antibodies. Due to the targetinduced conformational changes of aptamers, these oligonucleotides can be applied in various biosensing platforms. In this work, aptamers directed against the vascular endothelial growth factor (VEGF) were used as a model system.

Aptazymes: Expanding the Specificity of Natural Catalytic Nucleic Acids by Application of In Vitro Selected Oligonucleotides.

Aptazymes are synthetic molecules composed of an aptamer domain and a catalytic active nucleic acid unit, which may be a ribozyme or a DNAzyme. In these constructs the aptamer domain serves as a molecular switch that can regulate the catalytic activity of the ribozyme or DNAzyme subunit. This regulation is triggered by binding of the aptamers target molecule, which causes significant structural changes in the aptamer and thus in the entire aptazyme.

Aptamer-Modified Magnetic Beads in Biosensing.

Magnetic beads (MBs) are versatile tools for the purification, detection, and quantitative analysis of analytes from complex matrices. The superparamagnetic property of magnetic beads qualifies them for various analytical applications. To provide specificity, MBs can be decorated with ligands like aptamers, antibodies and peptides.

Comparing two conventional methods of emulsion PCR and optimizing of Tegosoft-based emulsion PCR.

The selection of aptamers represents a promising route in the development of high affinity ligands. In these processes the formation of by-products is a common problem during the PCR-based amplification of complex oligonucleotide libraries. One approach to overcome this drawback is to separate each template oligonucleotide into an individual reaction compartment provided by a droplet.

Detection of ochratoxin A by aptamer-assisted real-time PCR-based assay (Apta-qPCR).

Detection of food toxins with high sensitivity is very important and challenging. Ochratoxin A (OTA) is frequently present as food contaminant in contaminated grains and grain derivatives such as bread and beer. In this work, a target-induced dissociation (TID) based aptamer-assisted real-time PCR-based assay (apta-qPCR) is developed that features effective detection of OTA.

Aptamer-based detection of adenosine triphosphate via qPCR.

Sensitive and specific detection and quantification of small molecules often remain challenging. We developed a novel magnetic bead-based aptamer-assisted real-time PCR (Apta-qPCR) assay to provide a versatile platform for quantification of small molecules. The assay has been realized for the detection of ATP as a model system.

Rapid and label-free detection of protein a by aptamer-tethered porous silicon nanostructures.

Protein A, which is secreted by and displayed on the cell membrane of Staphylococcus aureus is an important biomarker for S. aureus. Thus, its rapid and specific detection may facilitate the pathogen identification and initiation of proper treatment.

Living Cell Microarrays: An Overview of Concepts.

Living cell microarrays are a highly efficient cellular screening system. Due to the low number of cells required per spot, cell microarrays enable the use of primary and stem cells and provide resolution close to the single-cell level. Apart from a variety of conventional static designs, microfluidic microarray systems have also been established.

Aqueous Synthesis of PEGylated Quantum Dots with Increased Colloidal Stability and Reduced Cytotoxicity.

Ligands used on the surface of colloidal nanoparticles (NPs) have a significant impact on physiochemical properties of NPs and their interaction in biological environments. In this study, we report a one-pot aqueous synthesis of 3-mercaptopropionic acid (MPA)-functionalized CdTe/CdS/ZnS quantum dots (Qdots) in the presence of thiol-terminated methoxy polyethylene glycol (mPEG) molecules as a surface coordinating ligand. The resulting mPEG-Qdots were characterized by using ζ potential, FTIR, thermogravimetric (TG) analysis, and microscale thermophoresis (MST) studies.

Development of an aptamer-based affinity purification method for vascular endothelial growth factor.

Since aptamers bind their targets with high affinity and specificity, they are promising alternative ligands in protein affinity purification. As aptamers are chemically synthesized oligonucleotides, they can be easily produced in large quantities regarding GMP conditions allowing their application in protein production for therapeutic purposes. Several advantages of aptamers compared to antibodies are described in general within this paper.

Evaluation of CdTe/CdS/ZnS core/shell/shell quantum dot toxicity on three-dimensional spheroid cultures.

In this work, three-dimensional (3D) spheroid cultures of human adipose-derived mesenchymal stem cells (hAD-MSCs), with tissue-mimetic morphology through well developed cell-cell and cell-matrix interactions and distinct diffusion/transport characteristics, were assessed for dose-dependent toxic effects of red-emitting CdTe/CdS/ZnS quantum dots (Qdots). Morphological investigations and time-resolved microscopy analysis in addition to cell metabolic activity studies revealed that 3D spheroid cultures are more resistant to Qdot-induced cytotoxicity in comparison to conventional 2D cultures. The obtained results suggest the presence of two distinct cell populations in 2D cultures with different sensitivity to Qdots, however that effect wasn't observed in 3D spheroids.

Aptamer-modified magnetic beads in affinity separation of proteins.

Aptamers are valuable alternative ligands for affinity separations. Here, we describe the aptamer-based affinity separation of His-tagged proteins using an aptamer directed against the His-tag. The immobilization of the aptamer to magnetic beads is described as well as the aptamer-based purification and proper methods for the characterization of the process.

New, non-quinone fluorogeldanamycin derivatives strongly inhibit Hsp90.

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA-blocked mutant with all possible monofluoro 3-aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90.

Aptamer Microarrays-Current Status and Future Prospects.

Microarray technologies are state of the art in biological research, which requires fast genome, proteome and transcriptome analysis technologies. Often antibodies are applied in protein microarrays as proteomic tools. Since the generation of antibodies against toxic targets or small molecules including organic compounds remains challenging the use of antibodies may be limited in this context.

Label-free optical biosensors based on aptamer-functionalized porous silicon scaffolds.

A proof-of-concept for a label-free and reagentless optical biosensing platform based on nanostructured porous silicon (PSi) and aptamers is presented in this work. Aptamers are oligonucleotides (single-stranded DNA or RNA) that can bind their targets with high affinity and specificity, making them excellent recognition elements for biosensor design. Here we describe the fabrication and characterization of aptamer-conjugated PSi biosensors, where a previously characterized his-tag binding aptamer (6H7) is used as model system.

Identification of the target binding site of ethanolamine-binding aptamers and its exploitation for ethanolamine detection.

Aptamers are promising recognition elements for sensitive and specific detection of small molecules. We have previously selected ssDNA aptamers for ethanolamine, one of the smallest aptamer targets so far. The work presented here focuses on the determination of the binding region within the aptamer structure and its exploitation for the development of an aptamer-based assay for detection of ethanolamine.

Microarray-based screening of heat shock protein inhibitors.

Based on the importance of heat shock proteins (HSPs) in diseases such as cancer, Alzheimer's disease or malaria, inhibitors of these chaperons are needed. Today's state-of-the-art techniques to identify HSP inhibitors are performed in microplate format, requiring large amounts of proteins and potential inhibitors. In contrast, we have developed a miniaturized protein microarray-based assay to identify novel inhibitors, allowing analysis with 300 pmol of protein.