A label-free biomarkers detection platform relied on a bilayer long-wave infrared metamaterials BioNEMS sensor.

A novel approach based on optical Biological-Nano-Electro-Mechanical-Systems (BioNEMS) sensor is presented in this paper to provide highly sensitive and precise detection of biomolecules. The proposed BioNEMS sensor is relied on a bi-layer metamaterials structure, tuned by its wavelength. The presented biosensor consists of a BioNEMS membrane coated by Complementary Split Ring Resonators and an array of Split Ring Resonators cells on the substrate. While the immobilized bioreceptors adsorb the biomarkers (i.e. mRNA or protein), it causes a bending of the suspended membrane. This is due to the differential surface stress which is induced on the Nano-Electro-Mechanical-Systems structure. As a consequence, the coupling strength of two complementary metamaterial layers and thus the electromagnetic response of the biosensor are changed. Furthermore, the proposed device is designed and analyzed by numerical and analytical approaches in order to obtain its functional characteristics as follows: detection sensitivity of 21 967 nm/RIU, figure of merit of 327.8 RIU-1", mechanical sensitivity of 2.6µm/Nm-1" and resonant frequency of 4.92 kHz. According to the obtained results, the functional characteristics of the proposed label-free biosensor show its high potential for highly sensitive and accurate molecule detections, disease diagnosis as well as drug delivery tests for Lab-On-Chip systems.

A Biosensing Platform Based on Metamaterials BioNEMS for Lab-on-Chip Systems.

An optical nanoelectromechanical platform relied on a SRR metamaterial system is presented in this paper as a label-free biosensor. This structure includes a flexible BioNEMS (Bio-Nano-Electro-Mechanical Systems) transducer and a proposed SRR metamaterials for detection of biological changes. Metamaterial cells consist of two parts which are coupled with an air gap distance. A functionalized BioNEMS beam supports one part of the proposed metamaterial cells. When patient samples including target analytes is exposed to the NEMS beam surface, the specific bio-interactions are happened and the energy (surface stress type) is released on the surface. This energy, which is induced only to the one side of the movable beam, causes a differential surface stress and thus displaces the nanomechanical beam. As a result, the air distance between two separated cells of the metamaterial unit is changed. This leads to varying the cell coupling effect which excites plasmon modes in a different wavelength. Therefore, biological quantities can be measured by detecting the resonance wavelength changes. Moreover, analyzing the device by various approaches results its functional characteristics as follows: detection sensitivity of 4251 nm/RIU, figure of merit (FOM) of 500.1 RIU -1 , mechanical sensitivity of [Formula: see text]/Nm -1 and resonant frequency of 17.1 kHz. Consequently, this mechanism is important for label-free biosensing due to its high potential for sensitive and quantitative detection of target analytes which leads to accurate diagnosis of diseases or identification of drugs.

Alzheimer's Disease Diagnosis in the Preclinical Stage: Normal Aging or Dementia.

Alzheimer's disease (AD) progressively impairs the memory and thinking skills of patients, resulting in a significant global economic and social burden each year. However, diagnosis of this neurodegenerative disorder can be challenging, particularly in the early stages of developing cognitive decline. Current clinical techniques are expensive, laborious, and invasive, which hinders comprehensive studies on Alzheimer's biomarkers and the development of efficient devices for Point-of-Care testing (POCT) applications. To address these limitations, researchers have been investigating various biosensing techniques. Unfortunately, these methods have not been commercialized due to several drawbacks, such as low efficiency, reproducibility, and the lack of accurate identification of AD markers. In this review, we present diverse promising hallmarks of Alzheimer's disease identified in various biofluids and body behaviors. Additionally, we thoroughly discuss different biosensing mechanisms and the associated challenges in disease diagnosis. In each context, we highlight the potential of realizing new biosensors to study various features of the disease, facilitating its early diagnosis in POCT. This comprehensive study, focusing on recent efforts for different aspects of the disease and representing promising opportunities, aims to conduct the future trend toward developing a new generation of compact multipurpose devices that can address the challenges in the early detection of AD.

Ultrasensitive detection of vital biomolecules based on a multi-purpose BioMEMS for Point of care testing: digoxin measurement as a case study.

Rapid and label-free detection of very low concentrations of biomarkers in disease diagnosis or therapeutic drug monitoring is essential to prevent disease progression in Point of Care Testing. For this purpose, we propose a multi-purpose optical Bio-Micro-Electro-Mechanical-System (BioMEMS) sensing platform which can precisely measure very small changes of biomolecules concentrations in plasma-like buffer samples. This is realized by the development of an interferometric detection method on highly sensitive MEMS transducers (cantilevers). This approach facilitates the precise analysis of the obtained results to determine the analyte type and its concentrations. Furthermore, the proposed multi-purpose platform can be used for a wide range of biological assessments in various concentration levels by the use of an appropriate bioreceptor and the control of its coating density on the cantilever surface. In this study, the present system is prepared for the identification of digoxin medication in its therapeutic window for therapeutic drug monitoring as a case study. The experimental results represent the repeatability and stability of the proposed device as well as its capability to detect the analytes in less than eight minutes for all samples. In addition, according to the experiments carried out for very low concentrations of digoxin in plasma-like buffer, the detection limit of LOD = 300 fM and the maximum sensitivity of S = 5.5 × 1012 AU/M are achieved for the implemented biosensor. The present ultrasensitive multi-purpose BioMEMS sensor can be a fully-integrated, cost-effective device to precisely analyze various biomarker concentrations for various biomedical applications.