Detection of Pyocyanin Using a New Biodegradable SERS Biosensor Fabricated Using Gold Coated Zein Nanostructures Further Decorated with Gold Nanoparticles.

In this paper, a biodegradable gold coated zein film surface enhanced Raman spectroscopy (SERS) platform, with gold nanoparticles (AuNPs) deposited on the surface to further enhance the Raman signal, was used to detect pyocyanin (PYO), the toxin secreted by Pseudomonas aeruginosa. An inverted pyramid structure imprinted on a zein film and gold coated during the transfer process was further improved with the deposition and fixing of gold nanoparticles, which resulted in enhancement of the SERS signal by approximately a decade. This new platform served as a lab-on-a-chip sensor to enable the sensitive and rapid detection of PYO in drinking water. The size, distribution, and morphology of the zein film nanostructures including the presence and distribution of gold nanoparticles were characterized by scanning electron microscopy (SEM). The new zein-based platform has the advantage of being largely biodegradable compared with commercial silicon- or glass-based platforms. The limit of detection for PYO using the newly developed zein-based SERS sensor platform was calculated as 25 µM, considerably lower than the concentration of PYO in the blood of people with cystic fibrosis which has been reported to be 70 µM.

Implementation of Arithmetic Operations With Time-Free Spiking Neural P Systems.

Spiking neural P systems (SN P systems) are a class of distributed parallel computing devices inspired from the way neurons communicate by means of spikes. In most applications of SN P systems, synchronization plays a key role which means the execution of a rule is completed in exactly one time unit (one step). However, such synchronization does not coincide with the biological fact: in biological nervous systems, the execution times of spiking rules cannot be known exactly. Therefore, a "realistic" system called time-free SN P systems were proposed, where the precise execution time of rules is removed. In this paper, we consider building arithmetical operation systems based on time-free SN P systems. Specifically, adder, subtracter, multiplier, and divider are constructed by using time-free SN P systems. The obtained systems always produce the same computation result independently from the execution time of the rules.

Electrically induced conformational change of peptides on metallic nanosurfaces.

Surface immobilized biomolecular probes are used in many areas of biomedical research, such as genomics, proteomics, immunology, and pathology. Although the structural conformations of small DNA and peptide molecules in free solution are well studied both theoretically and experimentally, the conformation of small biomolecules bound on surfaces, especially under the influence of external electric fields, is poorly understood. Using a combination of molecular dynamics simulation and surface-enhanced Raman spectroscopy, we study the external electric field-induced conformational change of dodecapeptide probes tethered to a nanostructured metallic surface. Surface-tethered peptides with and without phosphorylated tyrosine residues are compared to show that peptide conformational change under electric field is sensitive to biochemical modification. Our study proposes a highly sensitive in vitro nanoscale electro-optical detection and manipulation method for biomolecule conformation and charge at bio-nano interfaces.

Green microfluidics made of corn proteins.

Petroleum-based polymer such as Poly(dimethylsiloxane) has been widely used to make mesoscale and microscale fluidic devices. The main drawback of such devices in disposable applications is the potential environmental pollution since they are not biodegradable. Biodegradable microfluidic devices have been fabricated out of zein, a prolamin protein found in corn, that can be utilized as disposable health and environmental-friendly micro-chips. Using stereo lithography and soft lithography, micro-chambers and micro-channels features have been replicated on zein films and enclosed zein microfluidic devices are created by bonding to glass substrate using a simple vapor-deposition method. The bonding strength of the zein microfluidic devices has been found to exceed the tensile strength of the zein film and hydraulic pressure, and fluid flow through large-area complex microfluidic designs shows no leakage or distortion. High optical clarity and fluorescent imaging in the zein microfluidic devices are demonstrated by visualizing micro-particles and Rhodamine B. Zein microfluidic devices enable truly disposable microfluidics with intrinsic biocompatibility and biodegradability that can be fabricated using existing techniques.