Metal-Organic Frameworks in Germany: from Synthesis to Function

Metal-organic frameworks (MOFs) are constructed from a combination of inorganic and organic units to produce materials which display high porosity, among other unique and exciting properties. MOFs have shown promise in many wide-ranging applications, such as catalysis and gas separations. In this review, we highlight MOF research conducted by Germany-based research groups. Specifically, we feature approaches for the synthesis of new MOFs, high-throughput MOF production, advanced characterization methods and examples of advanced functions and properties

Wearable Nano-Based Gas Sensors for Environmental Monitoring and Encountered Challenges in Optimization

With a rising emphasis on public safety and quality of life, there is an urgent need to ensure optimal air quality, both indoors and outdoors. Detecting toxic gaseous compounds plays a pivotal role in shaping our sustainable future. This review aims to elucidate the advancements in smart wearable (nano)sensors for monitoring harmful gaseous pollutants, such as ammonia (NH3), nitric oxide (NO), nitrous oxide (N2O), nitrogen dioxide (NO2), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), sulfur dioxide (SO2), ozone (O3), hydrocarbons (CxHy), and hydrogen fluoride (HF). Differentiating this review from its predecessors, we shed light on the challenges faced in enhancing sensor performance and offer a deep dive into the evolution of sensing materials, wearable substrates, electrodes, and types of sensors. Noteworthy materials for robust detection systems encompass 2D nanostructures, carbon nanomaterials, conducting polymers, nanohybrids, and metal oxide semiconductors. A dedicated section dissects the significance of circuit integration, miniaturization, real-time sensing, repeatability, reusability, power efficiency, gas-sensitive material deposition, selectivity, sensitivity, stability, and response/recovery time, pinpointing gaps in the current knowledge and offering avenues for further research. To conclude, we provide insights and suggestions for the prospective trajectory of smart wearable nanosensors in addressing the extant challenges

Fully Integrated Biochip Platforms for Advanced Healthcare

Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications

Development of Nanofiber and Surface Plasmon Resonance Sensors for VOCs, Biochemical, and Bacterial Analysis

It is important to monitor potential exposure to various chemicals and toxicants that may adversely affect both human and environmental health. Biosensors have been developed to identify and quantify these analytes of interest in early warning systems and diagnosis devices. This dissertation implements nanomaterials, such as nanofibers and nanoparticles, into the biological recognition element of a biosensor for selectively and sensitively to detect trace analytes in either gas, liquid, or solid phases.This dissertation is an agglomeration of several different projects that investigates the novel applications of nanomaterials into biosensor designs with two major application focuses: nanofibers and surface plasmon resonance (SPR) The first half of this dissertation focuses on the application of nanofiber surfaces for sensor developments. The nanofibers were fabricated through electrospinning and incorporated into various sensor designs. The first project develops polyaniline nanofibers into a chemiresistor sensor for sensitive detection of VOCs (small chain alcohols) by employing variants of reduced graphene oxides. The second project applies the nanofiber property of high surface area to volume ratio to maximize surface adsorption of EDTA-functionalized silver nanoparticles (AgNPs) as the biorecognition element of this sensor. The EDTA-AgNPs formulates a nickel ion bridge for selective capture and release of NTA and His tagged proteins that can be detected through fluorescent spectroscopy. The second half of this dissertation transitions into the application of surface plasmon resonance for the development of biosensor signal transducers. The third project focused on combining the potential of 3D printing with gold nanoparticles (AuNPs) to create a novel integrated localized SPR (LSPR) sensor surface capable of sensitive protein detection. The synthesis of gold nanoparticles in-situ on a 3D printed prism surface enables the fabrication of a biosensor device for the disposable field of site usage with qualities comparable performances with sensors using commercial optical prisms. The last project focuses on developing an SPR experimental model of a double lipid bilayer membrane. This model mimics the unique structure of the double lipid bilayer membrane system found in the chloroplast, mitochondria, and gram-negative bacteria. This novel experimental model combined with SPR analysis creates a biosensor platform that enables the interrogation of chemical and protein interactions at interfaces such as the gram-negative bacteria cell wall and membrane system

Chemiresistive Nanosensors with Convex/Concave structures

航空航天学院陈松月副教授和化学化工学院、物理科学与技术学院双聘教授侯旭共同在国际著名期刊Nano Today (纳米科学领域权威刊物，IF=17.476)上发表了该文章。随着纳米技术和新材料的涌现，纳米传感器自90年代末出现后，因其高比表面积带来的优越性受到了越来越多的研究上和应用上的关注。本论文综述了基于一维结构（特殊凹凸结构）的化学电阻式纳米传感器，包括纳米线、纳米管和纳米孔道结构。根据传感器的不同材料和结构，分别讨论了它们的传感原理、材料和结构设计、界面设计、在不同领域中的应用。在此基础上讨论了各种纳米传感器在应用中表现出的优缺点。并提出了未来的发展将更注重传感器的稳定性、灵敏度、特异性以及器件的可集成性。【Abstract】Nanosensors have attracted tremendous, scientific and application, interests promoted by the advances in nanotechnology and emerging new nanomaterials. There has been rapid progress in developing chemiresistive nanosensors, and these sensor technologies are being transferred among a variety of different fields, from energy, environment to life science. This review presents nanomaterials with special convex/concave structures used for chemiresistive sensors, which mainly composed of one-dimensional conductive structures, e.g. nanowires, nanotubes, nanopores and nanochannels. Furthermore, designing, operation, and applications of current chemiresistive nanosensors are discussed to give an outlook of this field, especially for ionic solution and gas as the working chemical environments. The authors hope this review could inspire the active interest in the scientific field of sensor development and application.This work was supported by the National Natural Science Foundation of China (grant numbers 61601387, 21673197, U1505243), the Natural Science Foundation of Fujian Province of China (grant number 2017J05107), Young Overseas High-level Talents Introduction Plan, the 111 Project (grant number B16029), the Open Funding of State Key Laboratory of Precision Measuring Technology and Instruments (grant number pilab1709), and the Fundamental Research Funds for the Central Universities of China (grant number 20720170050). 该工作得到了国家自然科学基金（项目批准号: 61601387, 21673197, U1505243），福建省自然科学基金（项目批准号: 2017J05107），高等学校学科创新引智计划（项目批准号: B16029），精密测试技术及仪器国家重点实验室开放基金（项目批准号: pilab1709）和厦门大学校长基金（项目批准号: 20720170050）等资助与支持

Design, fabrication and characterisation of gas sensors based on nanohybrid materials

Hoy en día, la necesidad de monitorizar y controlar el medio ambiente es a cada vezmás importante debido al creciente nivel de gases tóxicos que provienen de la expansiónde las actividades industriales, amenazando así el medio ambiente y la salud humana. Eldesarrollo de la nano-tecnología ha permitido fabricar sensores de gases portables,altamente sensibles, selectivos, de bajo coste y de bajo consumo de potencia.Los nanotubos de carbono (NTC) están ganando un interés a cada vez más considerablepor parte de la comunidad científica debido a su geometría y morfología únicas y susexcelentes propiedades electrónicas, mecánicas, térmicas i ópticas. Esto hace de ellosunos candidatos prometedores para un amplio rango de aplicaciones como por ejemplonuevos sensores de gases con propiedades mejoradas. En este contexto, mediante lapresente tesis, se ha realizado un profundo estudio para explorar las propiedades dediferentes sensores basados en nano-materiales híbridos constituidos por nanotubos decarbono junto a otros materiales con el fin de detectar gases tóxicos de manera eficiente.El trabajo realizado consistió en el diseño, la fabricación, la caracterización, y laoptimización de nanosensores híbridos.Esta tesis fue financiada en el marco del proyecto Europeo "Nano2hybrids", cuyoobjetivo era de diseñar la interfaz de las nano-partículas del metal con los nanotubos decarbono a través del control de los defectos estructurales y químicos producidos por ladescarga de un plasma de radiofrecuencia y aplicarlo a la detección de gases. Elbenceno fue elegido como gas principal, debido a sus graves efectos tóxicos a niveles depocas ppb y también debido a la no existencia en el mercado de un detector de bajocoste para benceno. De hecho, no hay en el estado de la técnica, un sensor de gas quepuede detectar de forma selectiva este gas a nivel operativo de ppb y trabajando atemperatura ambiente. Así, el reto de esta tesis era obtener un sensor altamente sensible,selectivo y estable, portátil y de bajo coste para la detección de benceno.En este sentido, se estudiaron exhaustivamente diferentes materiales basados ennanotubos de carbono funcionalizados, decorados con nanopartículas de metal o biendecorados o mezclados con óxidos metálicos, en términos de su adecuación para ladetección de gases (por ejemplo, sus sensibilidad, selectividad, estabilidad, y elmecanismo de detección, etc.). En particular se estudió la detección de diferentes gasescomo (benceno (C6H6 ), monóxido de carbono (CO), dióxido de nitrógeno (NO2), eletileno (C2H4), el sulfuro de hidrógeno (H2S), amoníaco (NH3) y agua (H2O)). Nuestrastareas consistieron en investigar experimentalmente y teóricamente el efecto de lascondiciones de preparación de los materiales (p.e. el tratamiento con plasma, lanaturaleza del precursor y tamaño de las nanoparticulas de metales), fabricación delsensor (p.e., técnica de deposición, el efecto del tipo de metal del los electrodos delsensor), y de las condiciones de caracterización del sensor (p.e., temperatura deoperación, flujo de gas,) sobre las propiedades sensoras de los mismos. Todo ello hapermitido adquirir conocimientos, explicar los mecanismos de funcionamiento en elsensado de gases de los diferentes materiales investigados y con ello desarrollar unsensor de gases adecuado para la detección de benceno.Hemos encontrado que los materiales híbridos que consisten en nanotubos tratados conplasma de oxígeno y decorados con diferentes nanopartículas de metal, muestran unamayor capacitad de detección a temperatura ambiente respecto a los nanotubos decarbono en bruto o los funcionalizados sólo con plasma. Las propiedades interfacialesde los materiales híbridos resultantes pueden ser adaptadas, lo que ofrece una enormeflexibilidad para el ajuste de sus propiedades sensoras. Cuando se combinaron en unamatriz de micro-sensores que opera a temperatura ambiente, nanotubos decorados condiferentes metales, de forma que unos resulten sensibles al benceno y otros insensibles,esto permitió por primera vez la realización de un prototipo de bajo coste capaz dedetectar selectivamente y a temperatura ambiente el benceno presente a nivel de trazas(por debajo de 50 ppbs) en una mezcla de gases. El prototipo realizado presenta unostiempos de respuesta y de recuperación de 60 s y 10 minutos respectivamente además deuna buena estabilidad y reproducibilidad. Este prototipo se encuentra protegido por unapatente que ha sido licenciada a una compañía que se encargará de la comercializaciónindustrial del producto.In the last few years, there has been a growing demand for monitoring the environment,especially with the increasing concern by the release of toxic gases emitted by manmadeactivities. The development of nanotechnology has created a huge potential for buildinghighly sensitive, selective, low cost, and portable gas sensors with low powerconsumption.Nowadays, carbon nanotubes are receiving an intense interest from the scientificcommunity, due to their unique geometry, morphology, electronic, mechanical, thermaland optical properties, which make them a promising candidate for many industrialapplications including new gas sensors for the detection of toxic species. In this context,in this thesis a deep study is devoted to explore the sensing properties of differenthybrid nanomaterials based on carbon nanotubes for an efficient detection of toxicgases. The design, fabrication, characterization, and optimization of gas sensors usinghybrid materials have been carried out.This thesis was financially supported by the European project "Nano2hybrids", whichexploits the interface design of metal nanocluster-carbon nanotube hybrids via controlof structural and chemical defects in a plasma discharge, for designing gas sensors withsuperior performance. Benzene was chosen as the principal target gas due to its serioustoxic effects at low ppb levels and the fact that there are no reliable, low cost andselective benzene detectors in the market. In fact, no gas sensor able to selectivelydetect this gas at ppb levels and operating at ambient temperature has been reported upto now in the literature. So, the challenge of the project was to fabricate sensitive,highly selective, stable, portable, and low cost benzene gas sensor employing hybridnanomaterials.Herein, functionalized MWCNTs, metal decorated MWCNTs, and metal oxidedecorated MWCNTs or metal oxide and MWCNT mixtures were deeply investigated interms of their gas sensing performances (e.g, sensitivity, selectivity, stability, detectionmechanism,. etc) towards the detection of different gases (benzene (C6H6), carbonmonoxide (CO), nitrogen dioxide (NO2), ethylene (C2H4), hydrogen sulfide (H2S),ammonia (NH3), and water (H2O)). Our tasks were to investigate experimentally andtheoretically the effects of material preparation conditions (e.g., plasma treatment,nanocluster precursor and size), sensor fabrication (e.g., deposition technique,electrodes sensor metal), and sensor characterization conditions (e.g., operatingtemperature, gas flow) on the gas sensing properties of our devices, and to acquireknowledge in order to develop a selective benzene detector. Based on experimental andtheoretical results, different mechanisms for the interaction between gases and thehybrid materials tested have been proposed.We found that hybrid materials consisting of oxygen plasma treated multiwalled carbonnanotubes decorated with different metal nanoparticles showed room temperaturesensing capability. Responsiveness to gases of these hybrid materials was higher thanthat of pristine or plasma functionalized carbon nanotubes. Metal decoated CNTs can betailored for the recognition of different gases and vapors with different reactivities,which offers enormous flexibility for tuning the interfacial properties of the resultinghybrid materials and thus, of their sensing properties. When combined in a microsensorarray operating at room temperature, the use of benzene-sensitive and benzeneinsensitivemetal-decorated multiwalled carbon nanotubes, allowed for the first time theimplementation of a low cost detector prototype, which can selectively detect benzenewhen present at trace levels (below 50 ppb) in a gas mixture. Sensors present responseand recovery times of 60 s and 10 min respectively, good stability and reproducibility.This type of sensors are protected by a patent, and licensed to a company for industrialcommercialization

Novel Enhancements and Analytical Applications of Amperometric Nitric Oxide (NO) Sensors

Improvements to the selectivity of the Shibuki-design and solid-polymer electrolyte (SPE) based amperometric NO sensors are described in this dissertation. Novel applications of SPE-based NO sensors are also demonstrated with results compared with those obtained using chemiluminescence as a reference method. The selectivity with respect to aqueous-phase interfering species of Shibuki-type sensors is substantial; however, certain gas-phase species such as CO are major interferences. By increasing the pH of the internal electrolyte solution, the selectivity of Shibuki-design sensors vs. CO can be improved by up to 100-fold (Chapter 2). This improvement is the result of more extensive Pt-oxides formed on the electrode surface that inhibits CO adsorption. Gas-phase detection of NO requires a high surface area electrode, which can be deposited into the surface of a solid-polymer electrolyte (SPE) such as Nafion (Chapter 3). Pt-Nafion sensors exhibited excellent performance with a limit of detection (LOD) of 4.3 ± 1.1 ppb and response time under 5 s. Detection of NO released from NO-donor doped biomedical polymer films and electrochemically reduced nitrite solutions was performed using Pt-Nafion sensors and repeated using chemiluminescence. Strong agreement was found for both the NO-releasing films and the electrochemically reduced nitrite solution. In Chapter 4, several strategies were explored to enhance the selectivity of the Pt-Nafion sensors. Filtration of the sample gas was shown to be promising for the removal of CO (using an activated carbon fiber filter) and NH3 (using various acid traps) although further optimization of conditions is needed. Sampled current/sensitivity voltammetry of NO, CO and NH3 did not reveal a potential range with substantially improved selectivity and applying the principles developed in Chapter 2 (elevated internal electrolyte) also proved ineffective because Nafion cannot transport anions such as OH- or NO2-. Despite the current selectivity limitations, Pt-Nafion sensors have other useful applications (Chapter 5). The determination of nitrite and GSNO was examined with LOD of 26±5 nM and 17±10 nM, respectively. NO delivered by a cost-effective inhaled nitric oxide therapy (INO) system was monitored with no adverse effects from altering O2 concentration. NO2 sensing and scrubbing were also developed as potential safety measures.PhDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133344/1/zzhen_1.pd