Ultrasensitive deafness gene DNA hybridization detection employing a fiber optic Mach-Zehnder interferometer: Enabled by a black phosphorus nanointerface

Unpacking the packaged optical fiber bio-sensors: understanding the obstacle for biomedical application

A biosensor is a promising alternative tool for the detection of clinically relevant analytes. Optical fiber as a transducer element in biosensors offers low cost, biocompatibility, and lack of electromagnetic interference. Moreover, due to the miniature size of optical fibers, they have the potential to be used in microfluidic chips and in vivo applications. The number of optical fiber biosensors are extensively growing: they have been developed to detect different analytes ranging from small molecules to whole cells. Yet the widespread applications of optical fiber biosensor have been hindered; one of the reasons is the lack of suitable packaging for their real-life application. In order to translate optical fiber biosensors into clinical practice, a proper embedding of biosensors into medical devices or portable chips is often required. A proper packaging approach is frequently as challenging as the sensor architecture itself. Therefore, this review aims to give an unpack different aspects of the integration of optical fiber biosensors into packaging platforms to bring them closer to actual clinical use. Particularly, the paper discusses how optical fiber sensors are integrated into flow cells, organized into microfluidic chips, inserted into catheters, or otherwise encased in medical devices to meet requirements of the prospective applications.

Biosensors for Public Health and Environmental Monitoring: The Case for Sustainable Biosensing

Climate change is a profound crisis that affects every aspect of life, including public health. Changes in environmental conditions can promote the spread of pathogens and the development of new mutants and strains. Early detection is essential in managing and controlling this spread and improving overall health outcomes. This perspective article introduces basic biosensing concepts and various biosensors, including electrochemical, optical, mass-based, nano biosensors, and single-molecule biosensors, as important sustainability and public health preventive tools. The discussion also includes how the sustainability of a biosensor is crucial to minimizing environmental impacts and ensuring the long-term availability of vital technologies and resources for healthcare, environmental monitoring, and beyond. One promising avenue for pathogen screening could be the electrical detection of biomolecules at the single-molecule level, and some recent developments based on single-molecule bioelectronics using the Scanning Tunneling Microscopy-assisted break junctions (STM-BJ) technique are shown here. Using this technique, biomolecules can be detected with high sensitivity, eliminating the need for amplification and cell culture steps, thereby enhancing speed and efficiency. Furthermore, the STM-BJ technique demonstrates exceptional specificity, accurately detects single-base mismatches, and exhibits a detection limit essentially at the level of individual biomolecules. Finally, a case is made here for sustainable biosensors, how they can help, the paradigm shift needed to achieve them, and some potential applications.

Highly efficient, label free, ultrafast plasmonic SERS biosensor (silver nanoarrays/Si) to detect GJB2 gene expressed deafness mutations in real time validated with PCR studies

Rapid diagnostics of any gene mutations related to organ loss is highly demanded now-a days to consume time as well to reduce cost. Currently, Surface enhanced Raman spectroscopy (SERS) is evolved to be a rapid investigating tool to screen gene mutations down to single molecule sensing with regard to the design and development of substrates used for sensing. The current research focuses on particular towards direct detection of deafness mutations associated with single and dual sites related to GJB2 gene. SERS Sensor construction is achieved with plasmonic silver nanoarrays on Si (SNA/Si) substrate by effortless wet chemical methods (Reaction time: 35 s; Concentration: 20 mM). The fabricated SNA/Si facilitates direct sensing of the deafness mutations of GJB2 gene in single as well dual sites with the enhancement of plasmonic hotspots. Normal DNA DMF-33 (GGGGGG) as well as Mutant DNA at single site DMF-9 (GGGGG) were validated by their guanine fingerprint Raman bands intensity quenching for mutant DNA DMF-9 at 1366 cm-1 and 1595 cm-1 respectively. Likewise, double mutations in DMF-19 are substitutional from G to A, portrayed highly intense fingerprint of Adenine Raman bands at 739 cm-1, 1432 cm-1, 1572 cm-1 in comparison to normal DNA (DMF-33). The findings were well analyzed with Raman mapping data which carries almost 625 scans for each DNA sample. The fabricated sensor exhibited the highest sensitivity towards DNA detection down to 0.1 pg/μL with utmost reproducibility. The current study aims to bring in creation of library files for deafness mutations to facilitate clinical diagnostics in a simple and rapid approach.

Label-Free Biochemical Sensing Using Processed Optical Fiber Interferometry: A Review

Over the last 20 years, optical fiber-based devices have been exploited extensively in the field of biochemical sensing, with applications in many specific areas such as the food processing industry, environmental monitoring, health diagnosis, bioengineering, disease diagnosis, and the drug industry due to their compact, label-free, and highly sensitive detection. The selective and accurate detection of biochemicals is an essential part of biosensing devices, which is to be done through effective functionalization of highly specific recognition agents, such as enzymes, DNA, receptors, etc., over the transducing surface. Among many optical fiber-based sensing technologies, optical fiber interferometry-based biosensors are one of the broadly used methods with the advantages of biocompatibility, compact size, high sensitivity, high-resolution sensing, lower detection limits, operating wavelength tunability, etc. This Review provides a comprehensive review of the fundamentals as well as the current advances in developing optical fiber interferometry-based biochemical sensors. In the beginning, a generic biosensor and its several components are introduced, followed by the fundamentals and state-of-art technology behind developing a variety of interferometry-based fiber optic sensors. These include the Mach-Zehnder interferometer, the Michelson interferometer, the Fabry-Perot interferometer, the Sagnac interferometer, and biolayer interferometry (BLI). Further, several technical reports are comprehensively reviewed and compared in a tabulated form for better comparison along with their advantages and disadvantages. Further, the limitations and possible solutions for these sensors are discussed to transform these in-lab devices into commercial industry applications. At the end, in conclusion, comments on the prospects of field development toward the commercialization of sensor technology are also provided. The Review targets a broad range of audiences including beginners and also motivates the experts helping to solve the real issues for developing an industry-oriented sensing device.

Tapered Fiber Bioprobe Based on U-Shaped Fiber Transmission for Immunoassay

In this paper, a tapered fiber bioprobe based on Mach-Zehnder interference (MZI) is proposed. To retain the highly sensitive straight-tapered fiber MZI sensing structure, we designed a U-shaped transmission fiber structure for the collection of optical sensing signals to achieve a miniature-insert-probe design. The spectrum responses from the conventional straight-tapered fiber MZI sensor and our proposed sensor were compared and analyzed, and experimental results showed that our proposed sensor not only has the same sensing capability as the straight-tapered fiber sensor, but also has the advantages of being flexible, convenient, and less liquid-consuming, which are attributed to the inserted probe design. The tapered fiber bioprobe obtained a sensitivity of 1611.27 nm/RIU in the refractive index detection range of 1.3326-1.3414. Finally, immunoassays for different concentrations of human immunoglobulin G were achieved with the tapered fiber bioprobe through surface functionalization, and the detection limit was 45 ng/mL. Our tapered fiber bioprobe has the insert-probe advantages of simpleness, convenience, and fast operation. Simultaneously, it is low-cost, highly sensitive, and has a low detection limit, which means it has potential applications in immunoassays and early medical diagnosis.

Label-free, ultra-low detection limit DNA biosensor using high quality optical microcavity functionalized by DNA tetrahedral nanostructure probes

This study proposes and demonstrates a novel label-free DNA biosensor using high quality optical microcavity functionalized by 3D DNA nanostructure probes. To achieve ultra-low limit DNA biosensing, optical sensing interface of the hollow-core, thin wall-thickness microcavity was functionalized by self-assembled DNA tetrahedral nanostructure (DTN) probes with size of 17 bp and length of ∼5.8 nm. High efficiency binding of the DTN probes with the optical sensor interface and the target ssDNA are achieved. Whispering gallery mode (WGM) spectra with high-Q factor of >107 are excited and traced for DNA detection inside the microfluidic channel of the microcavity, with a small sample volume of nL. Incorporation of nanoscale DTN probes onto surface of the optical microcavity makes it an effective way for increasing efficient probe density and eliminating entanglement between DNA probes, thus ∼1000 times lower detection limit is achieved as compared to using 1D ssDNA probes. Due to its desirable merits of label-free, ultra-low LoD, real time and compact size, the proposed DNA biosensor has broad application prospects in bioengineering and medical diagnosis.