High-performance olfactory receptor-derived peptide sensor for trimethylamine detection based on Steglich esterification reaction and native chemical ligation connection

High-performance peptide biosensor based on unified structure of lotus silk

The sensitive materials of current gas sensors are fabricated on planar substrates, significantly limiting the quantity of sensitive material available on the sensor and the complete exposure of the sensitive material to the target gas. In this work, we harnessed the finest, resilient, naturally degradable, and low-cost lotus silk derived from plant fibers, to fabricate a high-performance bio-sensor for toxic and harmful gas detection, employing peptides with full surface connectivity. The proposed approach to fabricate gas sensors eliminated the need for substrates and electrodes. To ascertain the effectiveness and versatility of the sensors created via this method, sensors for three distinct representative gases (isoamyl alcohol, 4-vinylanisole, and benzene) were prepared and characterized. These sensors surpassed reported detection limits by at least one order of magnitude. The inherent pliancy of lotus silk imparts adaptability to the sensor architecture, facilitating the realization of 1D, 2D, or 3D configurations, all while upholding consistent performance characteristics. This innovative sensor paradigm, grounded in lotus silk, represents great potential toward the advancement of highly proficient bio gas sensors and associated applications.

Biomimetic Wearable Sensors: Emerging Combination of Intelligence and Electronics

Owing to the advancement of interdisciplinary concepts, for example, wearable electronics, bioelectronics, and intelligent sensing, during the microelectronics industrial revolution, nowadays, extensively mature wearable sensing devices have become new favorites in the noninvasive human healthcare industry. The combination of wearable sensing devices with bionics is driving frontier developments in various fields, such as personalized medical monitoring and flexible electronics, due to the superior biocompatibilities and diverse sensing mechanisms. It is noticed that the integration of desired functions into wearable device materials can be realized by grafting biomimetic intelligence. Therefore, herein, the mechanism by which biomimetic materials satisfy and further enhance system functionality is reviewed. Next, wearable artificial sensory systems that integrate biomimetic sensing into portable sensing devices are introduced, which have received significant attention from the industry owing to their novel sensing approaches and portabilities. To address the limitations encountered by important signal and data units in biomimetic wearable sensing systems, two paths forward are identified and current challenges and opportunities are presented in this field. In summary, this review provides a further comprehensive understanding of the development of biomimetic wearable sensing devices from both breadth and depth perspectives, offering valuable guidance for future research and application expansion of these devices.

High-performance pyramid-SiNWs biosensor for NH3gas detection

NH3is widely existed in the environment and is closely associated with various health issues. Additionally, detecting the small amounts of NH3exhaled by patients with liver and kidney diseases offers potential opportunities for painless early disease diagnosis. Therefore, there is an urgent need for a convenient, rapid, and highly sensitive real-time NH3monitoring method. This work presents a high-performance NH3sensor based on olfactory receptor-derived peptides (ORPs) on a pyramid silicon nanowires (SiNWs) structure substrate. First, we successfully fabricated the pyramid-SiNWs structure on a silicon substrate using a chemical etching method. Subsequently, by dehydrative condensation reaction between the amino groups on APTES and the carboxyl groups of ORPs, ORPs were successfully immobilized onto the pyramid-SiNWs structure. This methodology allows the ORPs sensor on the pyramid-SiNWs substrate to detect NH3as low as 1 ppb, which was the reported lowest limit of detection, with a higher response rate compared to ORPs sensors on flat SiNWs substrates. The sensors also exhibit good sensitivity and stability for NH3gas detection. The results show the feasibility and potential applications of ORPs-pyramid-SiNWs structure sensors, in the fields of food safety, disease monitoring, and environmental protection, etc.

Investigating on sensing mechanism of MoS2-FET biosensors in response to proteins

Field-effect transistor (FET) biosensors based on two-dimensional materials have gained extensive attention due to their high sensitivity, label-free detection capability, and fast response. Molybdenum disulfide (MoS2), with tunable bandgap, high surface-to-volume ratio, and smooth surface without dangling bonds, is a promising material for FET biosensors. Previous reports have demonstrated the fabrication of MoS2-FET biosensors and their high sensitivity detection of proteins. However, most prior research has focused on the realization of MoS2-FETs for detecting different kinds of proteins or molecules, while comprehensive analysis of the sensing mechanism and dominant device factors of MoS2-FETs in response to proteins is yet to investigate. In this study, we first fabricated MoS2-FET biosensor and detected different types of proteins (immunoglobulin G (IgG),β-actin, and prostate-specific antigen (PSA)). Secondly, we built the model of the device and analyzed the sensing mechanism of MoS2-FETs in response to proteins. Experimental and modeling results showed that the induced doping effect and gating effect caused by the target protein binding to the device surface were the major influential factors. Specifically, the channel doping concentration and gate voltage (Vg) offset exhibited monotonic change as the concentration of the protein solution increases. For example, the channel doping concentration increased up to ∼37.9% and theVgoffset was ∼-1.3 V with 10-7μgμl-1IgG. The change was less affected by the device size. We also investigated the effects of proteins with opposite acid-base properties (β-actin and PSA) to IgG on the device sensing mechanism.β-actin and PSA exhibited behavior opposite to that of IgG. Additionally, we studied the response behavior of MoS2-FETs with different dimensions and dielectric materials (channel length, MoS2thickness, dielectric layer thickness, dielectric layer material) to proteins. The underlying mechanisms were discussed in details. This study provides valuable guidelines for the design and application of MoS2-FET biosensors.

Synergy of Two Intermolecular Hydrogen Bonds Promotes Highly Sensitive and Selective Room-Temperature Dimethyl Methylphosphonate Sensing: A Case of rGO-Based Gas Sensors

The development of room-temperature chemiresistive gas sensors with low limit of detection, high sensitivity, and selectivity for dimethyl methylphosphonate (DMMP) detection remains a challenge. Herein, a synergy of the two intermolecular hydrogen bond-promoted approach was proposed to fabricate a room-temperature DMMP sensor with enhanced performances. As a proof of concept, ternary p-hexafluoroisopropanol phenyl (HFIP) functionalized polypyrrole-reduced graphene oxide hybrids (HFIP-PPy-rGO) were rationally designed. During the sensing process, rGO serves as a conductive carrier, ensuring that the sensors operate at room temperature, and both HFIP and PPy act as adsorption sites for DMMP through hydrogen bonding interactions. As expected, the HFIP-PPy-rGO sensor exhibits high selectivity and sensitivity to DMMP. Besides, the HFIP-PPy-rGO sensor also possesses excellent linear response to DMMP and long-term stability. Experimental results and quartz crystal microbalance measurements prove that the specific recognition of DMMP is realized by forming two intermolecular hydrogen bonds between HFIP and DMMP, as well as PPy and DMMP. Additionally, the introduction of HFIP groups also contributes to adjusting device conductivity, enhancing signal conversion function. To put the DMMP sensor into potential practical application, the obvious sensing response to different DMMP concentrations in soil was confirmed, and a wireless detection system was built to realize real-time monitoring of DMMP concentrations in the surroundings. Overall, this study provides a facile and practical solution for improving the sensing performance of room-temperature sensors based on the hydrogen bond theory.

Artificial Olfactory Biohybrid System: An Evolving Sense of Smell

The olfactory system can detect and recognize tens of thousands of volatile organic compounds (VOCs) at low concentrations in complex environments. Bioelectronic nose (B-EN), which mimics olfactory systems, is becoming an emerging sensing technology for identifying VOCs with sensitivity and specificity. B-ENs integrate electronic sensors with bioreceptors and pattern recognition technologies to enable medical diagnosis, public security, environmental monitoring, and food safety. However, there is currently no commercially available B-EN on the market. Apart from the high selectivity and sensitivity necessary for volatile organic compound analysis, commercial B-ENs must overcome issues impacting sensor operation and other problems associated with odor localization. The emergence of nanotechnology has provided a novel research concept for addressing these problems. In this work, the structure and operational mechanisms of biomimetic olfactory systems are discussed, with an emphasis on the development and immobilization of materials. Various biosensor applications and current developments are reviewed. Challenges and opportunities for fulfilling the potential of artificial olfactory biohybrid systems in fundamental and practical research are investigated in greater depth.

Sex Pheromone Receptor-Derived Peptide Biosensor for Efficient Monitoring of the Cotton Bollworm Helicoverpa armigera

The cotton bollworm, Helicoverpa armigera (H. armigera), causes damage to a wide range of cultivated crops and is one of the pests with the greatest economic importance for global agriculture. Currently, the detection of H. armigera is based on manual sampling. A low limit of detection (LOD), convenient, and real-time monitoring method is urgently needed for its early warning and efficient management. Here, we characterized the amino acid sequence in the sex pheromone receptors (SPRs) recognizing the pheromone components of H. armigera by three-dimensional (3D) modeling and molecular docking. Next, sex pheromone receptor-derived peptides (SPRPs) were synthesized and conjugated to nanotubes by chemical connection. The modified nanotubes were used to fabricate a sensor capable of real-time monitoring of gaseous sex pheromone compounds with a low LOD (∼10 ppb for Z11-16:Ald) and selectivity, and the sensor was able to detect a single live H. armigera. Furthermore, the developed biosensor allowed direct monitoring of the pheromone release dynamics by female H. armigera and showed that the release was instantly reduced in response to light. Here, we report the first demonstration of a biosensing method for detecting gaseous sex pheromones and live H. armigera. The findings show the great potential of the SPRP sensor for broad applications in insect biology study and infestation monitoring.

Constructing Netlike Nanosheets of ZnO/BiOCl with Heterojunction as Robust Material for Electrochemical Amine Detection

The electrochemical sensing is a potential method for detection of trace toxic substance. Herein, the heterojunction of netlike ZnO/BiOCl nanosheets was constructed for the enhanced electrochemical detection of ammonia. Cyclic voltammetry and linear sweep voltammetry were used to investigate the electrochemical performance. The results show that the ZnO/BiOCl-modified electrode exhibits higher sensitivity towards ammonia compared with the ZnO and BiOCl-based electrodes, which is ascribed to band structure and fast electron transfer. The high response of 11.8 μA mM^-1 and a low detection limit (LOD) of 0.25 μM are achieved. In addition, the ZnO/BiOCl material exhibits high selectivity, repeatability and stability. The better linear relationship between concentration and current (R² =0.99) is significant for quantitative detection of ammonia, implying that netlike ZnO/BiOCl nanosheets can serve as electrochemical sensing platform for detecting toxic substance. This research provides a strategy for fabricating two-dimensional netlike materials and regulating heterojunctions used for electrochemical application.

Nanoporous Graphene Oxide-Based Quartz Crystal Microbalance Gas Sensor with Dual-Signal Responses for Trimethylamine Detection

This paper presents a straightforward method to develop a nanoporous graphene oxide (NGO)-functionalized quartz crystal microbalance (QCM) gas sensor for the detection of trimethylamine (TMA), aiming to form a reliable monitoring mechanism strategy for low-concentration TMA that can still cause serious odor nuisance. The synthesized NGO material was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to verify its structure and morphology. Compared with the bare and GO-based QCM sensors, the NGO-based QCM sensor exhibited ultra-high sensitivity (65.23 Hz/μL), excellent linearity (R² = 0.98), high response/recovery capability (3 s/20 s) and excellent repeatability (RSD = 0.02, n = 3) toward TMA with frequency shift and resistance. Furthermore, the selectivity of the proposed NGO-based sensor to TMA was verified by analysis of the dual-signal responses. It is also proved that increasing the conductivity did not improve the resistance signal. This work confirms that the proposed NGO-based sensor with dual signals provides a new avenue for TMA sensing, and the sensor is expected to become a potential candidate for gas detection.

Ultrasensitive Flexible Olfactory Receptor-Derived Peptide Sensor for Trimethylamine Detection by the Bending Connection Method

Trimethylamine (TMA) is a harmful gas that exists ubiquitously in the environment; therefore, the sensitive and specific monitoring of TMA is necessary. In this work, we prepared ultrasensitive flexible sensors for TMA detection based on single-walled carbon nanotubes (SWCNTs) and olfactory receptor-derived peptides (ORPs) on low-cost plastic substrates. A novel bending connection method was developed by intentionally bending the interdigitated electrodes with SWCNTs to form a three-dimensional structure during the ORP-connection process, leading to the exposure of more modification sites. The method showed ∼4.7-fold more effective connection amount of the ORPs to SWCNTs compared to the conventional flat-condition connection method. The flexible ORP-SWCNT sensors could significantly improve the limit of detection for gaseous TMA from the reported lowest limit of 10 parts per quadrillion (ppq) to 0.1 ppq. The flexible ORP sensors also exhibited excellent sensitivity to vaporized TMA standards and TMA generated by different kinds of foods under different bending conditions. The results showed that the bending connection method in this work was effective for ultrasensitive flexible ORP sensors and their associated applications.

Progress in the Development of Detection Strategies Based on Olfactory and Gustatory Biomimetic Biosensors

The biomimetic olfactory and gustatory biosensing devices have broad applications in many fields, such as industry, security, and biomedicine. The development of these biosensors was inspired by the organization of biological olfactory and gustatory systems. In this review, we summarized the most recent advances in the development of detection strategies for chemical sensing based on olfactory and gustatory biomimetic biosensors. First, sensing mechanisms and principles of olfaction and gustation are briefly introduced. Then, different biomimetic sensing detection strategies are outlined based on different sensing devices functionalized with various molecular and cellular components originating from natural olfactory and gustatory systems. Thereafter, various biomimetic olfactory and gustatory biosensors are introduced in detail by classifying and summarizing the detection strategies based on different sensing devices. Finally, the future directions and challenges of biomimetic biosensing development are proposed and discussed.