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Recent Submissions

  • Realization of an Ultrasensitive and Highly Selective OFET NO2 Sensor: The Synergistic Combination of PDVT-10 Polymer and Porphyrin–MOF

    Yuvaraja, Saravanan; Surya, Sandeep Goud; Chernikova, Valeriya; Vijjapu, Mani Teja; Shekhah, Osama; Bhatt, Prashant; Chandra, Suman; Eddaoudi, Mohamed; Salama, Khaled N. (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2020-04-13) [Article]
    Organic field-effect transistors (OFETs) are emerging as competitive candidates for gas sensing applications due to the ease of their fabrication process combined with the ability to readily fine-tune the properties of organic semiconductors. Nevertheless, some key challenges remain to be addressed, such as material degradation, low sensitivity, and poor selectivity toward toxic gases. Appropriately, a heterojunction combination of different sensing layers with multifunctional capabilities offers great potential to overcome these problems. Here, a novel and highly sensitive receptor layer is proposed encompassing a porous 3D metal-organic framework (MOF) based on isostructural-fluorinated MOFs acting as an NO2 specific preconcentrator, on the surface of a stable and ultrathin PDVT-10 organic semiconductor on an OFET platform. Here, with this proposed combination we have unveiled an unprecedented 700% increase in sensitivity toward NO2 analyte in contrast to the pristine PDVT-10. The resultant combination for this OFET device exhibits a remarkable lowest detection limit of 8.25 ppb, a sensitivity of 680 nA/ppb, and good stability over a period of 6 months under normal laboratory conditions. Further, a negligible response (4.232 nA/%RH) toward humidity in the range of 5%-90% relative humidity was demonstrated using this combination. Markedly, the obtained results support the use of the proposed novel strategy to achieve an excellent sensing performance with an OFET platform.
  • Fully Integrated Indium Gallium Zinc Oxide NO2 Gas Detector

    Vijjapu, Mani Teja; Surya, Sandeep Goud; Yuvaraja, Saravanan; Zhang, Xixiang; Alshareef, Husam N.; Salama, Khaled N. (ACS Sensors, American Chemical Society (ACS), 2020-02-24) [Article]
    We report an amorphous indium gallium zinc oxide (IGZO)-based toxic gas detection system. The microsystem contains an IGZO thin-film transistor (TFT) as a sensing element and exhibits remarkable selectivity and sensitivity to low concentrations of nitrogen dioxide (NO2). In contrast to existing metal oxide-based gas sensors, which are active either at high temperature or with light activation, the developed IGZO TFT sensor is operable at room temperature and requires only visible light activation to revive the sensor after exposure to NO2. Furthermore, we demonstrate air-stable sensors with an experimental limit of detection of 100 ppb. This is the first report on metal oxide TFT gas sensors without heating or continuous light activation. Unlike most existing gas sensing systems that take care of identifying the analytes alone, the developed IGZO microsystem not only quantifies NO2 gas concentration but also yields a 5-bit digital output. The compact microsystem, incorporating readout and analog-to-digital conversion modules developed using only two TFTs, paves the way for inexpensive toxic gas monitoring systems.
  • Fully Transparent Transceiver Using Single Binary Oxide Thin Film Transistors

    Hassan, Ali H.; Hota, Mrinal Kanti; Alshammari, Fwzah Hamud; Alshareef, Husam N.; Salama, Khaled N. (Advanced Electronic Materials, Wiley, 2020-02-03) [Article]
    Using one binary oxide, a fully transparent thin-film transistor (TFT)-based transceiver circuit is presented. The proposed transceiver circuit is fabricated entirely using an atomic layer deposition process. Moreover, the proposed circuit presents two modulation schemes: frequency shift keying and ON/OFF keying. The fabricated TFTs exhibit saturation mobility, threshold voltage, a subthreshold swing, and an ON/OFF ratio of 18.2 cm2 V−1 s−1, 0.9 V, 419 mVdec−1, and 109 times, respectively. Finally, the circuit functionality is demonstrated by the word “KAUST” as a Morse code.
  • KAUSTat: A Wireless, Wearable, Open-Source Potentiostat for Electrochemical Measurements

    Ahmad, Rafiq; Surya, Sandeep Goud; Sales, José Batista; Mkaouar, Hend; Catunda, Sebastian Yuri Cavalcanti; Belfort, Diomadson Rodrigues; Lei, Yongjiu; Wang, Zhong Lin; Baeumner, Antje; Wolfbeis, Otto S.; Alshareef, Husam N.; Salama, Khaled N. (IEEE, 2020-01-15) [Conference Paper]
    Advanced technology is needed every day for wireless, wearable sensors/potentiostats to record real-time measurements and monitor the chemical processes and physiological signals of the human body. Most of the potentiostats present on the market work as
  • Methanol and Humidity Capacitive Sensors Based on Thin Films of MOF Nanoparticles

    Andrés, Miguel A.; Vijjapu, Mani Teja; Surya, Sandeep Goud; Shekhah, Osama; Salama, Khaled N.; Serre, Christian; Eddaoudi, Mohamed; Roubeau, Olivier; Gascón, Ignacio (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2020-01-07) [Article]
    The successful development of modern gas sensing technologies requires high sensitivity and selectivity coupled to cost effectiveness, which implies the necessity to miniaturize devices while reducing the amount of sensing material. The appealing alternative of integrating nanoparticles of a porous metal−organic framework (MOF) onto capacitive sensors based on interdigitated electrode (IDE) chips is presented. We report the deposition of MIL-96(Al) MOF thin films via the Langmuir−Blodgett (LB) method on the IDE chips, which allowed the study of their gas/ vapor sensing properties. First, sorption studies of several organic vapors like methanol, toluene, chloroform, etc. were conducted on bulk MOF. The sorption data revealed that MIL-96(Al) presents high affinity toward water and methanol. Later on, ordered LB monolayer films of MIL-96(Al) particles of ∼200 nm were successfully deposited onto IDE chips with homogeneous coverage of the surface in comparison to conventional thin film fabrication techniques such as drop-casting. The sensing tests showed that MOF LB films were selective for water and methanol, and short response/recovery times were achieved. Finally, chemical vapor deposition (CVD) of a porous thin film of Parylene C (thickness∼250−300 nm) was performed on top of the MOF LB films to fabricate a thin selective layer. The sensing results showed an increase in the water selectivity and sensitivity, while those of methanol showed a huge decrease. These results prove the feasibility of the LB technique for the fabrication of ordered MOF thin films onto IDE chips using very small MOF quantities
  • All-Oxide Thin Film Transistors and Rectifiers Enabling On-Chip Capacitive Energy Storage

    Wang,Zhenwei; Alshammari, Fwzah Hamud; Omran, Hesham; Hota, Mrinal Kanti; Al-Jawhari, Hala A.; Salama, Khaled N.; Alshareef, Husam N. (Advanced Electronic Materials, Wiley, 2019-09-08) [Article]
    All-oxide, fully-transparent thin film transistors and rectifiers, processed entirely by atomic layer deposition, have been developed for on-chip capacitive energy storage. Fully depleted thin film transistor (TFT) operation is achieved by optimizing the carrier concentration in the ZnO channels. The TFTs show an average saturation mobility of 10.5 cm2 V−1 s−1, a stable positive turn-on voltage of 0.88 V, a low subthreshold swing of 0.162 V dec−1, and the entire device achieves an overall transmittance of 85%. The field-effect rectifiers (FER) are fabricated based on short-circuiting the gate and drain electrodes of the TFT structure. Rectification ratio of 3.5 × 106 is achieved in DC measurements. Under AC input, the rectifiers can steadily operate at an input frequency up to 10 MHz and amplitude (peak to peak) up to 20 V. The rectifier can be used for signal processing applications with frequency up to 1 MHz. The energy storage utility of the rectifiers is demonstrated by rectifying AC input signals and successfully charging home-made electrochemical on-chip microsupercapacitors. The results demonstrate that integrated, all-oxide thin film rectifiers can be used for on-chip capacitive energy storage.
  • Photo-carrier extraction by triboelectricity for carrier transport layer-free photodetectors

    Hsiao, Vincent K.S.; Leung, Siu Fung; Hsiao, Yung Chi; Kung, Po Kai; Lai, Ying Chih; Lin, Zong Hong; Salama, Khaled N.; Alshareef, Husam N.; Wang, Zhong Lin; He, Jr-Hau (Nano Energy, Elsevier Ltd, 2019-08-02) [Article]
    Efficient carrier extraction is essential for high performance optoelectronic devices, such as solar cells and photodetectors. Conventional strategies to separate photogenerated carriers typically involve the fabrication of a p-n junction by doping and the use of carrier selective charge transport layers. However, these techniques often require high temperature processes or costly materials. In this work, we demonstrate an innovative and simple approach of extracting photogenerated carriers from organometallic halide perovskites utilizing triboelectricity. The triboelectric device can be easily fabricated at low temperature using inexpensive materials on plastic substrates, enabling it to be readily integrated into self-powered optoelectronic devices. As a proof-of-concept, we fabricated a triboelectrics-assisted perovskite photodetector, which enabled us to study the surface charges generated using different electrical contacts and bending conditions performed by the device. With the assistance of a triboelectric charge-induced electric field, the photocurrent and transient photoresponses were significantly enhanced. Furthermore, we integrated the plastic triboelectric device with a flexible photodetector to demonstrate this carrier collection approach in flexible/wearable electronics. To the best of our knowledge, this work is the first report of carrier extraction in organometallic halide perovskite photodetector by triboelectric charges, demonstrating a potential use for carrier extraction in other semiconductor-based optoeletronic devices.
  • Recent progress and perspectives of gas sensors based on vertically oriented ZnO nanomaterials

    Ahmad, Rafiq; Majhi, Sanjit Manohar; Zhang, Xixiang; Swager, Timothy M.; Salama, Khaled N. (Advances in Colloid and Interface Science, Elsevier BV, 2019-05-22) [Article]
    Vertically oriented zinc oxide (ZnO) nanomaterials, such as nanorods (NRs), nanowires (NWs), nanotubes (NTs), nanoneedles (NNs), and nanosheets (NSs), are highly ordered architectures that provide remarkable properties for sensors. Furthermore, these nanostructures have fascinating features, including high surface-area-to-volume ratios, high charge carrier concentrations, and many surface-active sites. These features make vertically oriented ZnO nanomaterials exciting candidates for gas sensor fabrication. The development of efficient methods for the production of vertically oriented nanomaterial electrode surfaces has resulted in improved stability, high reproducibility, and gas sensing performance. Moving beyond conventional fabrication processes that include binders and nanomaterial deposition steps has been crucial, as the materials from these processes suffer from poor stability, low reproducibility, and marginal sensing performance. In this feature article, we comprehensively describe vertically oriented ZnO nanomaterials for gas sensing applications. The uses of such nanomaterials for gas sensor fabrication are discussed in the context of ease of growth, stability on an electrode surface, growth reproducibility, and enhancements in device efficiency as a result of their unique and advantageous features. In addition, we summarize applications of gas sensors for a variety of toxic and volatile organic compound (VOC) gases, and we discuss future directions of the vertically oriented ZnO nanomaterials.
  • Trianglamine hydrochloride crystals for a highly sensitive and selective humidity sensor

    Nanaiah, Karumbaiah Chappanda; Chaix, Arnaud; Surya, Sandeep Goud; Moosa, Basem; Khashab, Niveen M.; Salama, Khaled N. (Sensors and Actuators B: Chemical, Elsevier BV, 2019-05-08) [Article]
    In this work, we present a highly sensitive and selective capacitive humidity sensor. Trianglamine hydrochloride is used as the sensing material, which is synthesized by a [3+3] cyclocondensation reaction between terpthaldehyde and 1R,2R-cyclohexanediamine followed by addition of hydrochloric acid and vapor diffusion of acetone. The crystalline trianglamine hydrochloride salts are dispersed in acetonitrile and then coated on interdigitated electrode substrates by drop casting. The sensor response is characterized for relative humidity (RH) ranging from 5% to 95%. The sensor has a nonlinear response, where the sensitivity increases with an increase in RH. The sensor demonstrates, on average, normalized sensitivities of 0.015 and 6.9 per percent of RH below and above 65% RH, respectively. In addition, the sensor is characterized for hysteresis, long-term stability, effect of temperature, and selectivity. The hysteresis of the sensor is a maximum of about 20% RH and is stable for over 25 days. Temperature analysis of the sensors shows that the sensitivity decreases with increase in temperature. The material is shown to be highly selective with respect to volatile organic compounds (VOCs) and toxic/corrosive gasses. Overall, trianglamine hydrochloride is a promising material for developing a highly sensitive and selective capacitive transduction-based humidity sensor.
  • Integration of Electrochemical Microsupercapacitors with Thin Film Electronics for On-Chip Energy Storage

    Hota, Mrinal Kanti; Jiang, Qiu; Wang,Zhenwei; Wang, Zhong Lin; Salama, Khaled N.; Alshareef, Husam N. (Advanced Materials, Wiley, 2019-05-06) [Article]
    The development of self-powered electronic systems requires integration of on-chip energy-storage units to interface with various types of energy harvesters, which are intermittent by nature. Most studies have involved on-chip electrochemical microsupercapacitors that have been interfaced with energy harvesters through bulky Si-based rectifiers that are difficult to integrate. This study demonstrates transistor-level integration of electrochemical microsupercapacitors and thin film transistor rectifiers. In this approach, the thin film transistors, thin film rectifiers, and electrochemical microsupercapacitors share the same electrode material for all, which allows for a highly integrated electrochemical on-chip storage solution. The thin film rectifiers are shown to be capable of rectifying AC signal input from either triboelectric nanogenerators or standard function generators. In addition, electrochemical microsupercapacitors exhibit exceptionally slow self-discharge rate (≈18.75 mV h-1 ) and sufficient power to drive various electronic devices. This study opens a new avenue for developing compact on-chip electrochemical micropower units integrated with thin film electronics.
  • A Simple, Easy to Fabricate Miniaturized Microfluidic Gradient Generator for Drug Testing Devices

    Sivashankar, Shilpa; Alamoudi, Kholod; Agambayev, Sumeyra; Mashraei, Yousof; Mkaouar, Hend; Khashab, Niveen M.; Salama, Khaled N. (2018 30th International Conference on Microelectronics (ICM), Institute of Electrical and Electronics Engineers (IEEE), 2019-05-02) [Conference Paper]
    To date, although microfabrication technologies for fabricating a microfluidic device are advanced, they are still time-consuming and laborious. Hence, we demonstrate the fabrication of microfluidic devices with a fast and easy maskless Ultraviolet (UV) projection method based on a stereolithography process in less than 5 mins. The flow model analysis by COMSOL gives the design concept of the gradient demonstrated. The fabricated chip is a miniaturized 25×25 mm2 gradient chip that produces gradient by maintaining equal width and length of each channel throughout the device. The design of the gradient is dependent on diffusion of molecules and hence is well suited for low flow rate applications such as drug delivery or cell related studies. The biocompatibility of the resins in their native form and with surface modification was evaluated by injecting cell culture medium to culture Human cervical cell line (HeLa) cells. Drug (Doxorubicin) screening was demonstrated by the viability of HeLa cells using Cell Counting Kit-8 (CCK-8) calorimetric assay. The miniaturized size of the chip aids these gradient generators to find applications in drug testing Lab-on-chip/Micro Total analysis systems (μTAS) and organ-on-chip devices.
  • A MXene-Based Wearable Biosensor System for High-Performance In Vitro Perspiration Analysis

    Lei, Yongjiu; zhao, Wenli; Zhang, Yizhou; Jiang, Qiu; He, Jr-Hau; Baeumner, Antje J; Wolfbeis, Otto S; Wang, Zhong Lin; Salama, Khaled N.; Alshareef, Husam N. (Small, Wiley, 2019-04-08) [Article]
    Wearable electrochemical biosensors for sweat analysis present a promising means for noninvasive biomarker monitoring. However, sweat-based sensing still poses several challenges, including easy degradation of enzymes and biomaterials with repeated testing, limited detection range and sensitivity of enzyme-based biosensors caused by oxygen deficiency in sweat, and poor shelf life of sensors using all-in-one working electrodes patterned by traditional techniques (e.g., electrodeposition and screen printing). Herein, a stretchable, wearable, and modular multifunctional biosensor is developed, incorporating a novel MXene/Prussian blue (Ti3 C2 Tx /PB) composite designed for durable and sensitive detection of biomarkers (e.g., glucose and lactate) in sweat. A unique modular design enables a simple exchange of the specific sensing electrode to target the desired analytes. Furthermore, an implemented solid-liquid-air three-phase interface design leads to superior sensor performance and stability. Typical electrochemical sensitivities of 35.3 µA mm-1 cm-2 for glucose and 11.4 µA mm-1 cm-2 for lactate are achieved using artificial sweat. During in vitro perspiration monitoring of human subjects, the physiochemistry signals (glucose and lactate level) can be measured simultaneously with high sensitivity and good repeatability. This approach represents an important step toward the realization of ultrasensitive enzymatic wearable biosensors for personalized health monitoring.
  • Fluorinated MOF platform for selective removal and sensing of SO2 from flue gas and air

    Tchalala, Mohammed; Bhatt, Prashant; Nanaiah, Karumbaiah Chappanda; Tavares, S R; Adil, Karim; Belmabkhout, Youssef; Shkurenko, Aleksander; Cadiau, Amandine; Heymans, N; De Weireld, G; Maurin, G; Salama, Khaled N.; Eddaoudi, Mohamed (Nature Communications, Springer Nature, 2019-03-22) [Article]
    Conventional SO2 scrubbing agents, namely calcium oxide and zeolites, are often used to remove SO2 using a strong or irreversible adsorption-based process. However, adsorbents capable of sensing and selectively capturing this toxic molecule in a reversible manner, with in-depth understanding of structure-property relationships, have been rarely explored. Here we report the selective removal and sensing of SO2 using recently unveiled fluorinated metal-organic frameworks (MOFs). Mixed gas adsorption experiments were performed at low concentrations ranging from 250 p.p.m. to 7% of SO2. Direct mixed gas column breakthrough and/or column desorption experiments revealed an unprecedented SO2 affinity for KAUST-7 (NbOFFIVE-1-Ni) and KAUST-8 (AlFFIVE-1-Ni) MOFs. Furthermore, MOF-coated quartz crystal microbalance transducers were used to develop sensors with the ability to detect SO2 at low concentrations ranging from 25 to 500 p.p.m.
  • One-step synthesis and decoration of nickel oxide nanosheets with gold nanoparticles by reduction method for hydrazine sensing application

    Ahmad, Rafiq; Beduk, Tutku; Majhi, Sanjit Manohar; Salama, Khaled N. (Sensors and Actuators B: Chemical, Elsevier BV, 2019-01-29) [Article]
    Morphology, nanoscale features, and tunable properties are the fundamentals of nanomaterials to many applications in use nowadays. Exciting approaches are utilized for developing and exploring new nanomaterials that enable broader impact on a variety of application areas. In this study, we synthesized thin nickel oxide (NiO) nanosheets using wet chemistry process and modified their surface with gold (Au) nanoparticles (NPs) via reduction method to obtain new hybrid (Au NPs-NiO nanosheets) nanomaterial. The morphological analysis of NiO and Au NPs-NiO nanosheets revealed small, uniform, thin, and smooth surface of NiO nanosheets formation, which become rough and decorated with small Au NPs uniformly over the NiO nanosheets surface. The synthesized NiO nanosheets and hybrid (Au NPs-NiO nanosheets) nanomaterials were further utilized to modify the glassy carbon electrode for the fabrication of electrochemical-based hydrazine sensors. The fabricated sensors were applied to detect hydrazine using cyclic voltammetry (CV). And the obtained sensing properties of the hybrid nanomaterial-based sensor were comparatively better than the only NiO nanosheets based sensors. Further, hybrid nanomaterial-based sensors characterized in detail, which showed an excellent sensitivity of 31.75 μAnM cm. The lower detectable limit of hydrazine sensor was as low as ˜0.05 nM, which is considerably better than the other metal oxide-based hydrazine sensors. Better sensing performance of hybrid nanomaterial-based sensor likely stems from nanosheets small size, tiny thickness, and Au modification that significantly improve the surface area and lead a positive synergistic effect (an effect arises between two or more materials that produce an enhanced effect compared to their individual effects) for electrocatalytic reaction. We believe that this hybrid nanomaterial with excellent catalytic properties could be utilized as an efficient electrode material to design other chemical and biological sensors.
  • 3D-Printed Cross-Flow Mixer Gradient within Minutes for Microfluidic Applications

    Sivashankar, Shilpa; Mkaouar, Hend; Mashraei, Yousof; Alamoudi, Kholod; Khashab, Niveen M.; Salama, Khaled N. (2018 IEEE Biomedical Circuits and Systems Conference (BioCAS), Institute of Electrical and Electronics Engineers (IEEE), 2018-12-24) [Conference Paper]
    This paper reports on a compact new cross-flow 3D mixer that is integrated with a gradient generator into one device for toxicology applications. The device has two parts: the first mixes two solvents while the second generates gradients of the obtained solutions. The outlet of the 3D cross-flow mixer is integrated with a linear channel that aids in achieving this gradient by changing flow rates. The dye-visualization test confirm the functionality of mixer and gradient. The mesh structure of the mixer provided excellent mixing regime and is confirmed by experimental and simulation results. The compact size (25 × 25 × 3 mm) and the reduced cost ($1.5) of the device enable the device to be disposable. We aim to study doxorubicin drug at different concentration generated by the device to culture human embryonic kidney (HEK) from the 293-cell line enabling the devices to be used for cellular studies. The carefully designed geometry of the device finds applications in drug toxicology testing devices, micro-total analysis systems ( µ- TAs),and other lab-on-chip devices.
  • Concurrent Sensing of CO2 and H2O from Air Using Ultramicroporous Fluorinated Metal–Organic Frameworks: Effect of Transduction Mechanism on the Sensing Performance

    Tchalala, Mohammed; Belmabkhout, Youssef; Adil, Karim; Nanaiah, Karumbaiah Chappanda; Cadiau, Amandine; Bhatt, Prashant; Salama, Khaled N.; Eddaoudi, Mohamed (ACS Applied Materials & Interfaces, American Chemical Society (ACS), 2018-12-10) [Article]
    Conventional materials for gas/vapor sensing are limited to a single probe detection ability for specific analytes. However, materials capable of concurrent detection of two different probes in their respective harmful levels and using two types of sensing modes have yet to be explored. In particular, the concurrent detection of uncomfortable humidity levels and CO concentration (400-5000 ppm) in confined spaces is of extreme importance in a great variety of fields, such as submarine technology, aerospace, mining, and rescue operations. Herein, we report the deliberate construction and performance assessment of extremely sensitive sensors using an interdigitated electrode (IDE)-based capacitor and a quartz crystal microbalance (QCM) as transducing substrates. The unveiled sensors are able to simultaneously detect CO within the 400-5000 ppm range and relative humidity levels below 40 and above 60%, using two fluorinated metal-organic frameworks, namely, NbOFFIVE-1-Ni and AlFFIVE-1-Ni, fabricated as a thin film. Their subtle difference in a structure-adsorption relationship for HO and CO was analyzed to unveil the corresponding structure-sensing property relationships using both QCM- and IDE-based sensing modes.
  • A Comparative Study of Interdigitated Electrode and Quartz Crystal Microbalance Transduction Techniques for Metal–Organic Framework-Based Acetone Sensors

    Nanaiah, Karumbaiah Chappanda; Tchalala, Mohammed; Shekhah, Osama; Surya, Sandeep Goud; Eddaoudi, Mohamed; Salama, Khaled N. (Sensors, MDPI AG, 2018-11-12) [Article]
    We present a comparative study of two types of sensor with different transduction techniques but coated with the same sensing material to determine the effect of the transduction mechanism on the sensing performance of sensing a target analyte. For this purpose, interdigitated electrode (IDE)-based capacitors and quartz crystal microbalance (QCM)-based resonators were coated with a zeolitic⁻imidazolate framework (ZIF-8) metal⁻organic framework thin films as the sensing material and applied to the sensing of the volatile organic compound acetone. Cyclic immersion in methanolic precursor solutions technique was used for depositing the ZIF-8 thin films. The sensors were exposed to various acetone concentrations ranging from 5.3 to 26.5 vol % in N₂ and characterized/compared for their sensitivity, hysteresis, long-term and short-term stability, selectivity, detection limit, and effect of temperature. Furthermore, the IDE substrates were used for resistive transduction and compared using capacitive transduction.
  • Trianglamine-Based Supramolecular Organic Framework with Permanent Intrinsic Porosity and Tunable Selectivity

    Chaix, Arnaud; Mouchaham, Georges; Shkurenko, Aleksander; HOANG, PHUONG; Moosa, Basem; Bhatt, Prashant; Adil, Karim; Salama, Khaled N.; Eddaoudi, Mohamed; Khashab, Niveen M. (Journal of the American Chemical Society, American Chemical Society (ACS), 2018-10-08) [Article]
    Here we introduce for the first time a metal-free trianglamine-based supramolecular organic framework, T-SOF-1, with permanent intrinsic porosity and high affinity to CO2. The capability of tuning the pore aperture dimensions is also demonstrated by molecular guest encapsulation to afford excellent CO2/CH4 separation for natural gas upgrading.
  • Deposition of nanomaterials: A crucial step in biosensor fabrication

    Ahmad, Rafiq; Wolfbeis, Otto S.; Hahn, Yoon-Bong; Alshareef, Husam N.; Torsi, Luisa; Salama, Khaled N. (Materials Today Communications, Elsevier BV, 2018-09-29) [Article]
    Biosensor development includes the deposition of (nano)materials onto a conductive electrode surface, which is a crucial step for obtaining improved performance from the constructed biosensors. Various methods have been used to create a successful matrix of (nano)materials that ensures proper contact between the material and electrode surface. The purpose of (nano)material deposition is to provide a high surface area to improve the electroanalytical performance of biosensors by supporting the stable immobilization of enzymes in a more significant quantity as well as enhancing the catalytic or bioaffinity features. For decades, researchers have been using increasingly advanced methods not only for improving sensing performance, but also for improving stability, reproducibility, and mass production. In this review, we summarized the methods used for (nano)material deposition onto an electrode surface for efficient biosensor fabrication. An enhanced and optimized (nano)material deposition method is crucial for the mechanical stability and fabrication reproducibility of electrodes when designing a suitable biosensing device. In addition, we discussed the problems faced during biosensor application as well as the present challenges and prospects for superior deposition methods.
  • Biofunctionalized Two-Dimensional Ti3C2 MXenes for Ultrasensitive Detection of Cancer Biomarker

    Kumar, Saurabh; Lei, Yongjiu; Alshareef, Niman H.; Quevedo-Lopez, M.A.; Salama, Khaled N. (Biosensors and Bioelectronics, Elsevier BV, 2018-08-31) [Article]
    In this work, ultrathin Ti3C2-MXene nanosheets were synthesized by minimally intensive layer delamination methods, and uniformly functionalized with aminosilane (f-Ti3C2-MXene) to provide a covalent binding for the immobilized bio-receptor (anti-CEA) for label free, ultrasensitive detection of cancer biomarker (carcinoembryonic antigen, CEA). The effect of different redox probes on the electrochemical behavior of f-Ti3C2-MXene was investigated and found that hexaammineruthenium ([Ru(NH3)6]3+) is the preferable redox probe for biosensing. The fabricated biofunctionalized Ti3C2-MXene exhibits a linear detection range of 0.0001–2000 ngmL−1 with sensitivity of 37.9 µAng−1mLcm−2 per decade. The wider linear detection range of our f-Ti3C2-MXene is not only higher than previously reported pristine 2D nanomaterials, but is even comparable to other hybrid 2D nanomaterials. We believe that this work opens a new window for development of MXene-based highly sensitive DNA, aptamer, enzyme, antibody, and cell based biosensors, and could be further used in drug delivery application.

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