Nanobiomaterials for Biosensing
Published on Aug 15, 2016
Nanomaterial utilizes nanoscale engineering and system integration of existing materials to develop better materials and products. Applications of nanomaterials have made their presence strongly felt in various areas like healthcare, implants, and prostheses; smart textiles, energy generation and conservation with energy generating materials and highly efficient batteries, defence, security, terrorism, and surveillance .
Bionanomaterial’s research has emerged as a new exciting field, recognized as a new interdisciplinary frontier in the field of life science and material science. Great advances in nanobiochip materials, nanoscale biomimetic materials, nanomotors, nanocomposite materials, interface biomaterials, nanobiosensors, and nano-drug-delivery systems have the enormous prospect in industrial, defense, and clinical medicine applications.
Biomolecules assume the very important role in nanoscience and nanotechnology, for example, peptide nucleic acids (PNAs) replace DNA, act as a biomolecular tool/probe in the molecular genetics, diagnostics, cytogenetics, and have enormous potentials in pharmaceutics for the development of biosensors. Biosensor consists of a biosensing material and a transducer that can be used for detection of biological and chemical agents. Biosensing materials, like enzymes, antibodies, nucleic acid probes, cells, tissues, and organelles, selectively recognize the target analytes, whereas transducers like electrochemical, optical, piezoelectric, thermal, and magnetic devices can quantitatively monitor the biochemical reactions.
Nanoparticles in Biosensing
The sensitivity and performance of devices are being improved using nanomaterials. Nanomaterials with at least one of their dimensions ranging in scale from 1 to 100nm display unique and remarkably different property as compared
to its bulk because their nanometer size gives rise to high reactivity and other enhanced beneficial physical properties (electrical, electrochemical, optical, and magnetic) owing to nonlinearity after crossing the performance barrier threshold.
Their applications can potentially translate into new assays that improve upon the existing methods of biomolecular detection. Nanoparticles have been widely used in biosensors for detection of nucleic acids, peptide nucleic acid, and proteins. The enhancement in redox properties of gold nanoparticles coupled with silver has led to their widespread application as electrochemical labels in biosensor development with remarkable sensitivity.
The gold nanoparticles coated with ferrocenyl hexanethiol and streptavidin were used to monitor the DNA hybridization. Nanoparticles have also coupled with magnetic particles to capture target DNA, which then hybridizes with a secondary probe DNA tagged to metal nanoparticle and detected by anodic stripping voltammetry. A common problem with silver enhancement is a high background signal resulting from nonspecific precipitation of silver onto the substrate electrode and to overcome the setback, various electrode surface treatments and electrochemically or enzymatically controlled deposition methods of silver have reported.
For reducing the silver related background signal and increasing the sensitivity, a new system of electrochemical detection of DNA hybridization based on stripping voltammetry of enzymatically deposited silver has developed. The target DNA and a biotinylated DNA immobilized probe hybridize to a capture DNA probe tethered onto a gold electrode. NeutrAvidin- (NA-) conjugated alkaline phosphatase binds to the biotin of the detection probe on the electrode surface converting the nonelectroactive substrate to a reducing agent. The latter reduces the metal ions in solutions leading to the deposition of metal onto the electrode surface and DNA backbone.
Nanostructured Thin Films for Biosensing
Nanostructured thin films have opened the possibility to fabricate electrochemical sensors and biosensors with high power of detection due to intrinsic properties associated with their dimensions at nanoscale level. These interesting properties can be explained based on the organization level obtained when molecular arrangement is obtained at a solid conductor substrate. Also, the materials that can be used include a large range of organic and inorganic materials for films growth. Moreover, the possibility to improve the detection limit in biosensing devices can be also explained by using compatible materials such as natural polymers. The aim objective behind the utilization of these materials is to combine the high power of detection with preservation of the structural integrity of the biomolecules and, also, maintaining their biocatalytic activity
Nanostructured Materials for Biosensing Devices
Nanostructured materials are well known as interesting tools with specific physical and chemical properties due to quantum-size effects and large surface area that provides unique and different properties compared to bulk materials. The exploration of these different characteristics provides the possibility to improve biosensors properties and increase the power of detection throughout size and morphology control. Interesting approaches has reported about the high increase in electronic properties when metallic nanostructures are used as components for electrodes modification.
These includes the utilization of nanostructured materials with specific forms such 0D (quantum dots, nanoparticles), 1D (nanowires or carbon nanotubes) or 2D (metallic platelets or graphene sheets) orientation that reflects in their final properties. The next topic will be emphasize in biosensors fabrication using metallic nanoparticles (MNPs) as transducing elements on modified electrodes and some interesting electrochemical approaches used to improve biosensing performance.
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