Aptamer decorated PDA@magnetic silica microparticles for bacteria purification.

One significant constraint in the advancement of biosensors is the signal-to-noise ratio, which is adversely affected by the presence of interfering factors such as blood in the sample matrix. In the present investigation, a specific aptamer binding was chosen for its affinity, while exhibiting no binding affinity towards non-target bacterial cells. This selective binding property was leveraged to facilitate the production of magnetic microparticles decorated with aptamers.

Quartz crystal microbalance-based aptasensor integrated with magnetic pre-concentration system for detection of Listeria monocytogenes in food samples.

A fast and accurate identification of Listeria monocytogenes. A new quartz crystal microbalance (QCM) aptasensor was designed for the specific and rapid detection of L. monocytogenes.

Biosensor for ATP detection via aptamer-modified PDA@POSS nanoparticles synthesized in a microfluidic reactor.

This study introduces aptamer-functionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticles for adenosine triphosphate (ATP) detection where the POSS nanoparticles were synthesized in a one-step, continuous flow microfluidic reactor utilizing thermal polymerization. A microemulsion containing POSS monomers was generated in the microfluidic reactor which was designed to prevent clogging by using a continuous oil flow around the emulsion during thermal polymerization. Surfaces of POSS nanoparticles were biomimetically modified by polydopamine.

Antioxidant Activity and Hemocompatibility Study of Quercetin Loaded Plga Nanoparticles.

Quercetin (QU) is an important flavonoid compound presenting lots of biological activities, but its application has been limited due to its low aqueous solubility and instability. In this study, conducted to improve these properties of the quercetin, quercetin-encapsulated PLGA nanoparticles were prepared, characterized, and evaluated for antioxidant and hemolytic activity. Nanoparticles were produced by single emulsion solvent evaporation method.

Enhanced antitumor activity of carbendazim on HeLa cervical cancer cells by aptamer mediated controlled release.

Carbendazim, is a broad-spectrum fungicide and also a promising experimental antitumor drug as reproduction and developmental toxicant, which is currently under phase II preclinical trials. In this study, an approach based on controlled and targeted release with aptamers and mesoporous silica nanoparticles was investigated to improve the antitumor activity of carbendazim. To this end, we synthesized aptamer conjugated silica nanoparticles for testing cytotoxicity properties with human cervical adenocarcinoma (HeLa) cultured cells.

Rapid and label-free detection of Brucella melitensis in milk and milk products using an aptasensor.

In this work, a novel quartz crystal microbalance (QCM) aptasensor is designed for the diagnosis of Brucella melitensis bacteria, which affects the Mediterranean fever (brucellosis) from the zoonotic diseases that are very common in the Middle East Countries. The method is based on the selection of B. melitensis bacterium from solutions using B.

Design of an aptamer-based magnetic adsorbent and biosensor systems for selective and sensitive separation and detection of thrombin.

An aptasensor was designed for sensitive detection of thrombin using in biological fluids by integrating a magnetic aptamer-microbeads. To achieve this goal, the surface of gold plated QCM crystals was coated with L-cysteine and a thrombin binding DNA aptamer was immobilized on the L-cysteine coated QCM crystals surface via glutaraldehyde coupling. The binding interactions of thrombin to QCM crystals were characterized.

Fast and Sensitive Detection of in Milk Samples Using Aptamer-Functionalized Magnetic Silica Solid Phase and MCM-41-Aptamer Gate System.

General detection methods for include PCR analysis, immunologic methods, solid culturing techniques, and various microscopic studies. Milk and other food samples demonstrate an especially difficult challenge for direct detection, resulting from high biological contents. In this report, we aimed for fast detection of pathogen cells through an efficient magnetic capture and subsequent quick detection based on aptamer affinity.

Improvement stability and performance of invertase via immobilization on to silanized and polymer brush grafted magnetic nanoparticles.

In this study, magnetic nanoparticles (FeO) were modified sequentially with silica (FeO@SiO), glycidyl methacrylate (GMA) by surface initiated atom transfer radical polymerization (SI-ATRP) and hexamethylene diamine (as a spacer arm). The p(GMA) grafted and SA modified form (i.e.

Staphylococcus aureus detection in blood samples by silica nanoparticle-oligonucleotides conjugates.

A fast, specific and sensitive homogeneous assay for Staphylococcus aureus detection was developed by measuring the activity of secreted nuclease from the bacteria via a modified DNA oligonucleotide. As biosensor format, an effective system, Nanokeepers as previously reported, were used for triggered release of confined fluorophores, and hence specific detection of S. aureus on nuclease activity was obtained.

Small molecule detection by lateral flow strips via aptamer-gated silica nanoprobes.

A fast, sensitive and ratiometric biosensor strategy for small molecule detection was developed through nanopore actuation. The new platform engineers together, a highly selective molecular recognition element, aptamers, and a novel signal amplification mechanism, gated nanopores. As a proof of concept, aptamer gated silica nanoparticles have been successfully used as a sensing platform for the detection of ATP concentrations at a wide linear range from 100 μM up to 2 mM.

A facile and efficient method of enzyme immobilization on silica particles via Michael acceptor film coatings: immobilized catalase in a plug flow reactor.

A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK).

Fibrous polymer grafted magnetic chitosan beads with strong poly(cation-exchange) groups for single step purification of lysozyme.

Lysozyme is an important polypetide used in medical and food applications. We report a novel magnetic strong cation exchange beads for efficient purification of lysozyme from chicken egg white. Magnetic chitosan (MCHT) beads were synthesized via phase inversion method, and then grafted with poly(glycidyl methacrylate) (p(GMA)) via the surface-initiated atom transfer radical polymerization (SI-ATRP).

Development of a paper-type tyrosinase biosensor for detection of phenolic compounds.

A low-cost, portable, and disposable paper-type tyrosinase biosensor was developed for determination of phenolic compounds, using a paper-strip absorption method. Tyrosinase and a chromophore (3-methyl-2-benzothiazolinone hydrazone) were immobilized on paper strips to manufacture the biosensor, which was tested on a nontoxic substrate (l-dopamine). The biosensor was responsive to phenolic compounds such as 4-chlorophenol, catechol, m-cresol, and p-cresol.

Examination of fabrication conditions of acrylate-based hydrogel formulations for doxorubicin release and efficacy test for hepatocellular carcinoma cell.

The objective of the present study was to develop 2-hydroxypropyl methacrylate-co-polyethylene methacrylate [p(HPMA-co-PEG-MEMA)] hydrogels that are able to efficiently entrap doxorubicin for the application of loco-regional control of the cancer disease. Systemic chemotherapy provides low clinical benefit while localized chemotherapy might provide a therapeutic advantage. In this study, effects of hydrogel properties such as PEG chains length, cross-linking density, biocompatibility, drug loading efficiency, and drug release kinetics were evaluated in vitro for targeted and controlled drug delivery.

Pathogen detection by core-shell type aptamer-magnetic preconcentration coupled to real-time PCR.

The presence of pathogenic bacteria is a major health risk factor in food samples and the commercial food supply chain is susceptible to bacterial contamination. Thus, rapid and sensitive identification methods are in demand for the food industry. Quantitative polymerase chain reaction (PCR) is one of the reliable specific methods with reasonably fast assay times.

Design of a core-shell type immuno-magnetic separation system and multiplex PCR for rapid detection of pathogens from food samples.

We report an immuno-magnetic separation system developed by the immobilization of pathogen-specific antibodies on the core-shell magnetic beads. The magnetic beads were grafted with glycidylmethacrylate (GMA) using surface-initiated atom transfer radical polymerization (SI-ATRP). For immuno-magnetic separation (IMS) of target bacterial cells from others, antibodies for Escherichia coli and Salmonella enterica serovar Typhimurium cells were immobilized on the magnetic beads via glutaraldehyde coupling reaction.

Adsorption and separation of immunoglobulins by novel affinity core-shell beads decorated with Protein L and l-histidine.

A novel core shell beaded chromatographic materials was prepared by grafting of glycidyl methacrylate (GMA) on to the surface of poly(hydoxypropyl methacrylate/ethyleneglycol dimethacrylate), p(HPMA/EGDMA) beads via surface-initiated atom transfer radical polymerization (SI-ATRP). For grafting GMA, p(HPMA/EGDMA) beads were first modified with an ATRP initiator. A reaction with 2-bromo-2-methylpropionyl bromide of the hydroxyl groups of the beads led to ATRP initiator-covered surfaces.

Melting temperature of surface-tethered DNA.

A method for the accurate determination of the melting temperature (T(m)) of surface-immobilized DNA duplexes that exploits the fluorescence-quenching properties of gold is reported. A thiolated single-stranded DNA probe is chemisorbed onto a gold surface and then hybridized to a fluorophore-labeled complementary sequence. On formation of the duplex, the fluorescence of the label is effectively quenched by the gold surface.

Real-time apta-PCR for 20 000-fold improvement in detection limit.

A real-time apta-PCR for the ultrasensitive detection of thrombin is reported, where the thrombin aptamer acts not only as a biomolecular recognition element, but also as a label for amplification via real-time PCR. Aptamers can be easily converted to a reporter agent for detection by real-time PCR, simply via flanking of the aptamer's recognition moiety with primer sequences. The reported technique has the advantage of the ultrasensitivity achievable with immuno-PCR, but without the complications of addition of a DNA label, and is a technique generically applicable to all aptamers.

Label free optical sensor for Avidin based on single gold nanoparticles functionalized with aptamers.

Optical spectroscopy of a single gold nanoparticle, functionalized with an aptamer, is used to sense the specific binding of avidin. Herewith, the field of single noble metal nanoparticle biosensors is extended to the important field of aptamer based assays. The sensitivity of this initial, but not yet optimized apta-nano-sensor is in the range of 20 nM.

Fluorescent resonance energy transfer (FRET) based detection of a multiplex ligation-dependent probe amplification assay (MLPA) product.

A fluorescent resonance energy transfer (FRET)-based hybridization assay for detecting multiplex ligation-dependent probe amplification (MLPA) products has been developed, extending the diagnostic power of the technique and demonstrating the possibility of combining MLPA with microarrays for the detection of multiple mutations. FRET is one of the most commonly used detection techniques for hybridization assays. To investigate the applicability of FRET based detection of MLPA products, a sandwich assay was designed to detect gene copy number by exploiting an immobilized probe labeled with an acceptor dye, Alexa Fluor 555, which hybridises to specific PCR amplicons, followed by hybridization of a second probe labeled with the donor dye, Alexa Fluor 488.

Single-step purification of recombinant Thermus aquaticus DNA polymerase using DNA-aptamer immobilized novel affinity magnetic beads.

A DNA aptamer specific for Thermus aquaticus DNA polymerase (Taq-polymerase) was immobilized on magnetic beads, which were prepared in the presented study. The effect of various parameters including pH, temperaturem and aptamer concentration on the immobilization of 5'-thiol labeled DNA-aptamer onto glutaric dialdhyde activated magnetic beads was evaluated. The binding conditions of Taq-polymerase on the aptamer immobilized magnetic beads were studied using commercial Taq-polymerase to characterize the surface complexation reaction.