Nanobiotechnology for Molecular Diagnostics
Several nanosystems and nanodevices are available today for the sequencing of single DNA molecules. In the future, it is quite likely that numerous applications based on inorganic nanostructures will become available in medicine and biology as markers. Given the innate nanoscale of pores, receptors, and other functional living cell components, extensive monitoring and analysis of these components is made possible by evolution of a new class of nanoscale probes.
Nanomaterials are sensitive biological and chemical sensors and their surface properties cab ne easily modified. Therefore, nanowires can be arranged with any potential biological or chemical molecular recognition unit thereby making the wires analyte independent. Boron-doped silicon wires (SiNMs) are being used to create extremely sensitive, real-time electrical sensors for chemical and biological species. Biotin-modified SiNMs are used in the detection of streptavidin down to picomolar concentration range. The capability and the small size of these nanowires (semiconductor) for sensitive, real-time, and label-free detection of variety of biological and chemical species are diagnosed in in vivo diagnostics and array-based screening.
The sensors are electronically gated and respond to single molecule binding. Prototype sensors have demonstrated the ability to detect proteins, nucleic acids, and ions. These sensors operate in both gas and liquid phase thereby opening up numerous downstream applications.
Magnetic Nanoparticles- As MRI Contrast Agents
Magnetic nanoparticles were used as contrast agent for MRI refining molecular imaging. Targeted imaging of thrombosis or vascular inflammation has the chance to enable improved risk-assessment of atherosclerosis by the detection of plaques during acute complications. Cell death in heart is imaged in vivo by using magnetic nanoparticles (annexin-labeled), particularly AnxCLIO-Cy5.5. Magnetic nanoparticles that are conjugated with plasmid DNA, which expresses improved green-fluorescent protein and coated with chitosan, is injected into mice via the tail vein and then directed to the heart by an external magnet without needing to functionalize the nanoparticles; fluorescent imaging confirms their location.
Perfluorocarbon- Use in Cardiovascular Disorders
Perfluorocarbon (PFC) nanoparticles have provided an opportunity for combining local drug delivery and molecular imaging in cardiovascular disorders. Ligands such as peptides and monoclonal antibodies can be cross-linked the PFCs outer surface in order to enable targeting to biomarkers that are expressed within the vasculature.
PFC nanoparticles are constrained by the circulation size minimizing unintended binding to nontarget, extravascular tissues that express similar epitopes. Further, the prolonged circulatory half-life (approximately 5 hours) saturates the receptors without adding PEG or lipid surfactant polymerization. The use of targeted PFC nanoparticles has been proved in a variety of applications such as phantoms and animal models; this includes ruptured plaque diagnosis, atherosclerotic plaque quantification and its antiangiogenic treatment, and the localization and delivery of antirestenotic therapy post angioplasty.
Cardiovascular Monitoring- Sleep Apnea
Sleep apnea causes irregular heartbeat, cardiac arrest, hypertension, and stroke. It is important that patients are diagnosed and treated before anyone these deleterious effects occur leading to a dangerous sequence. Patients suspected of sleep apnea should be treated with in vivo sensors to monitor blood concentrations of oxygen and the functioning of the heart to detect issues during sleep. Further, cardio-specific antibodies are tagged with nanoparticles to allow doctors to visualize the movement of the heart while a patient experiences sleep apnea. This is done to determine both short and long term effects of apnea on cardiac function.
The important feature of atherosclerotic process is the angiogenic expansion of vasa vasorum in adventitia extending into the thickened atheroma intimal layer with other neovessels that originate from the primary arterial lumen. Focal angiogenesis's magnetic-resonance molecular imaging with the integrin-targeted contrast agents (paramagnetic) is reported with liposomes and PFC nanoparticles. Site-targeted PFC nanoparticles have also offered the opportunity for local drug delivery combined with molecular imaging.
Diagnosing and treating unstable plaque is a key area in which nanotechnology has an immediate impact. Nanoparticles that are fibrin specific allow in detecting and quantitating unstable plaque in susceptible patients; this could prove as an important feature in preventing cardiac arrest or stroke. Research is being conducted using probes to target plaque components for non-invasive detection of patients at high risk.
Extending this approach targeted nanoparticles, nanotechnology-based devices, or multifunctional macromolecules are capable of delivering therapy to a particular site, localized drug release is achieved either passively or actively. Targeted nanoparticles also stabilize vulnerable plaque (example, low-density lipoprotein). Devices can attach to unstable plaques warning patients and medical services of a plaque rupture to facilitate timely medical intervention.
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