Enzyme prodrug therapy achieves site-specific, personalized physiological responses to the locally produced nitric oxide

Nitric oxide (NO) is a highly potent but short-lived endogenous radical with a wide spectrum of physiological activities. In this work, we developed an enzymatic approach to the site-specific synthesis of NO mediated by biocatalytic surface coatings. Multilayered polyelectrolyte films were optimized as host compartments for the immobilized β-galactosidase (β-Gal) enzyme through a screen of eight polycations and eight polyanions. The lead composition was used to achieve localized production of NO through the addition of β-Gal–NONOate, a prodrug that releases NO following enzymatic bioconversion. The resulting coatings afforded physiologically relevant flux of NO matching that of the healthy human endothelium. The antiproliferative effect due to the synthesized NO in cell culture was site-specific: within a multiwell dish with freely shared media and nutrients, a 10-fold inhibition of cell growth was achieved on top of the biocatalytic coatings compared to the immediately adjacent enzyme-free microwells. The physiological effect of NO produced via the enzyme prodrug therapy was validated ex vivo in isolated arteries through the measurement of vasodilation. Biocatalytic coatings were deposited on wires produced using alloys used in clinical practice and successfully mediated a NONOate concentration-dependent vasodilation in the small arteries of rats. The results of this study present an exciting opportunity to manufacture implantable biomaterials with physiological responses controlled to the desired level for personalized treatment

MicroRNA Detection by DNA-Mediated Liposome Fusion

Membrane fusion is a process of fundamental importance in biological systems that involves highly selective recognition mechanisms for the trafficking of molecular and ionic cargos. Mimicking natural membrane fusion mechanisms for the purpose of biosensor development holds great potential for amplified detection because relatively few highly discriminating targets lead to fusion and an accompanied engagement of a large payload of signal-generating molecules. In this work, sequence-specific DNA-mediated liposome fusion is used for the highly selective detection of microRNA. The detection of miR-29a, a known flu biomarker, is demonstrated down to 18 nm within 30 min with high specificity by using a standard laboratory microplate reader. Furthermore, one order of magnitude improvement in the limit of detection is demonstrated by using a novel imaging technique combined with an intensity fluctuation analysis, which is coined two-color fluorescence correlation microscopy

Определение природных и техногенных радионуклидов в бальнеологических объектах

Quantitative detection of angiogenic biomarkers provides a powerful tool to diagnose cancers in early stages and to follow its progression during therapy. Conventional tests require trained personnel, dedicated laboratory equipment and are generally time-consuming. Herein, we propose our developed biosensing platform as a useful tool for a rapid determination of Angiopoietin-2 biomarker directly from patient plasma within 30 minutes, without any sample preparation or dilution. Bloch surface waves supported by one dimensional photonic crystal are exploited to enhance and redirect the fluorescence arising from a sandwich immunoassay that involves Angiopoietin-2. The sensing units consist of disposable and low-cost plastic biochips coated with the photonic crystal. The biosensing platform is demonstrated to detect Angiopoietin-2 in plasma samples at the clinically relevant concentration of 6 ng/mL, with an estimated limit of detection of approximately 1 ng/mL. This is the first Bloch surface wave based assay capable of detecting relevant concentrations of an angiogenic factor in plasma samples. The results obtained by the developed biosensing platform are in close agreement with enzyme-linked immunosorbent assays, demonstrating a good accuracy, and their repeatability showed acceptable relative variations

Magnetic biosensors: modelling and simulation

In the past few years, magnetoelectronics has emerged as a promising new platform technology in various biosensors for detection, identification, localisation and manipulation of a wide spectrum of biological, physical and chemical agents. The methods are based on the exposure of the magnetic field of a magnetically labelled biomolecule interacting with a complementary biomolecule bound to a magnetic field sensor. This Review presents various schemes of magnetic biosensor techniques from both simulation and modelling as well as analytical and numerical analysis points of view, and the performance variations under magnetic fields at steady and nonstationary states. This is followed by magnetic sensors modelling and simulations using advanced Multiphysics modelling software (e.g. Finite Element Method (FEM) etc.) and home-made developed tools. Furthermore, outlook and future directions of modelling and simulations of magnetic biosensors in different technologies and materials are critically discussed

Capsosomes: en route toward synthetic cellular systems

© 2011 Dr. Rona ChandrawatiEngineering artificial cells is currently an emerging area of research that involves constructing mimics of biological cells. These biomimetic cellular structures hold tremendous promise for the creation of next-generation therapeutic tools due to their ability to restore lost cellular functions. Amongst their potential applications, replenishing absent or malfunctioning enzymatic activities to degrade waste products or to support the synthesis of medically relevant biomolecules is a chief goal, which can provide long-term therapeutic solutions for chronic diseases. Artificial cells do not require the complex multifunctionality of their biological counterparts and can be more simply designed to perform a specific activity. A key approach in designing a cell-like system is a subcompartmentalized assembly, which is one of the features of biological cells that enable the performance of multiple complex biochemical reactions within confined environments. This thesis focuses on developing a bottom-up approach to assemble micron-sized vessels with a controlled number of enzyme-loaded subcompartments toward cell mimicry. Capsosomes, polymer hydrogel capsules containing controlled amounts of intact cargo-loaded liposomal subcompartments, were developed in this thesis and they represent a novel class of carrier system toward the design of bioinspired vehicles. Polymer capsules, assembled via the sequential deposition of interacting polymers onto particle templates (layer-by-layer technique, LbL) followed by core removal, serve as structurally stable scaffolds with tunable permeability that allow exchange of reagents and nutrients between the internal and external milieu – resembling cell membranes. On the other hand, liposomes divide the interior of the capsules into subcompartments and can stably encapsulate fragile hydrophobic and hydrophilic cargo, e.g., enzymes in order to conduct encapsulated catalysis – resembling cell organelles. The creation of (bio)degradable capsosomes is based on the sequential assembly of cargo-loaded liposomes and polymers onto sacrificial particle templates, followed by the LbL deposition of poly(N-vinylpyrrolidone) (PVP) and thiol-functionalized poly(methacrylic acid) (PMASH) via hydrogen bonding. Upon crosslinking the thiols of the PMASH and dissolution of the particle templates, colloidally stable capsosomes are obtained. The coassembly of polymers and liposomes was optimized via novel noncovalent linkage concept using tailor-made cholesterol-modified polymers and this unique approach facilitates stable incorporation of intact liposomes into polymer films. Spatial position of the subcompartments can be controlled, which yields capsosomes containing membrane-associated or “free-floating” subunits. Capsosomes exhibit size-dependent retention of the encapsulated cargo within the liposomal subunits. To prolong the stability of the liposomes in the compartmentalized assembly against degradative enzymes, the outer membrane of the capsosomes was surface functionalized with poly (ethylene glycol) (PEG). The functionality of capsosomes was demonstrated by triggered encapsulated (two-step) enzymatic catalysis. Capsosomes encapsulating glutathione reductase were able to generate glutathione, a potent antioxidant, while simultaneously releasing small therapeutic molecules, which highlights the ability of this subcompartmentalized assembly in addressing the complexity in therapeutic cell mimicry. The phase transition temperature of the liposomes was used as a trigger to initiate the enzymatic reactions, allowing capsosomes to be repeatedly used for multiple subsequent catalysis. Capsosomes with tailored properties present new opportunities en route to the development of functional cell mimics and the presented studies highlight crucial aspects for the successful applications of capsosomes as therapeutic artificial cells

Liposomes and lipid bilayers in biosensors

Biosensors for the rapid, specific, and sensitive detection of analytes play a vital role in healthcare, drug discovery, food safety, and environmental monitoring. Although a number of sensing concepts and devices have been developed, many longstanding challenges to obtain inexpensive, easy-to-use, and reliable sensor platforms remain largely unmet. Nanomaterials offer exciting possibilities for enhancing the assay sensitivity and for lowering the detection limits down to single-molecule resolution. In this review, we present an overview of liposomes and lipid bilayers in biosensing applications. Lipid assemblies in the form of spherical liposomes or two-dimensional planar membranes have been widely used in the design of biosensing assays; in particular, we highlight a number of recent promising developments of biosensors based on liposomes in suspension, liposome arrays, and lipid bilayers arrays. Assay sensitivity and specificity are discussed, advantages and drawbacks are reviewed, and possible further developments are outlined

Polydiacetylene-based sensors to detect food spoilage at low temperatures

Colorimetric gas sensors that detect early release of gases from food spoilage are of great importance in food safety and food conservation. Yet, such sensors are not broadly implemented as they are incompatible with food packaging and non-functional at the low temperatures at which food is stored. Here we report a low cost, highly sensitive ammonia sensor that can be easily incorporated into food packaging to monitor food spoilage at temperatures ranging between −20 °C and room temperature. To fabricate the film sensors, we polymerized self-assembled polydiacetylene vesicles stabilized with cellulose nanocrystals in chitosan matrix. By optimizing this fabrication process, we were able to increase the local concentration of polydiacetylene vesicles at the surface of the film, thus enhancing the operational temperature, response time, and sensitivity to ammonia. The polydiacetylene-based film sensors exhibited a distinctive blue-to-red colorimetric response after being exposed to spoiled meat, even at sub-zero temperatures