15 research outputs found
Electrochemical sensing of phytohormones: a facile method for real-time assessment of signaling dynamics
No full textReal-time monitoring of phytohormones in horticultural plants is difficult due to the lack of biosensors for these systems. Phytohormones that are associated with biotic stress responses, such as salicylic acid (SA), indole-3-acetic
acid (IAA), abscisic acid (ABA), and auxin, can be detected using chromatography and fluorescent sensors, but
these techniques are not suitable for field deployment. The electrochemically active nature of phytohormones can
be exploited to detect these molecules in living plant tissue. Incorporating phytohormone-selective minimally invasive
electrodes allows for continuous monitoring applications. This strategy can also be applied to electrochemically inactive phytohormones by utilizing impedimetric measurements.The technology highlighted herein is based on work by Abdullah Bukhamsin, Abdellatif Ait Lahcen, Jose De Oliveira Filho, Saptami Shetty, Khalil Moussi, Ikram Blilou, Jürgen Kosel, and Khaled Nabil Salama. No interests are declared
Implantable 3D Printed Drug Delivery System
No full textA miniaturized drug delivery system suitable for in-vivo biomedical applications is presented. The system consists of an electrolytic pump driving a micro bellows membrane as an actuator for delivery through microneedles. A two-photon polymerization 3D printing technique was used to fabricate a reservoir equipped with microneedles. Analytical characterization of the flow rate through the microneedles showed an outgoing flow rate ranging from 63 μL/min to 520 μL/min for an applied pressure of 0.1 to 1 kPa. The assembled system with an overall size of 3.9 mm × 2.1 mm × 2 mm achieved delivery of 4 ± 0.5 μL within 12 seconds of actuation. A penetration test of the microneedle into a skin-like material confirms its potential for transdermal delivery.This work was funded and supported by King Abdullah University of Science and Technology (KAUST)
TOWARDS FIELD PLANT DIAGNOSTICS MINIMALLY INVASIVE SENSING PLATFORMS FOR EARLY DETECTION OF CROP STRESS AND YIELD OPTIMIZATION
No full textPlant diseases cause annual losses of 10-16% of the global harvests, which has an equivalent value of $220 billion USD.[1] Limiting these losses necessitates the proactive and sustained use of strict phyto-sanitary and remediation measures. This can incur a large burden on stakeholders. For instance, under these guidelines, in Saudi Arabia alone, approximately 4.3 million trees had to be treated to contain a variety of plant diseases.[2] Plants have developed a wide array of adaptations to biotic and abiotic stressors. The onset of stress can trigger a rapid cascade of signaling molecules that modulate the plant's response to the stressor. Relying on the phenotypic changes that occur post-stress does not leave an adequate time window for intervention prior to disease spread or commercial losses.[3] However, by monitoring the physiological levels of the plant’s signaling molecules, early diagnosis may be facilitated. Tracking the spatio-temporal dynamics of plant hormones, secondary messengers, and bio-impedance can facilitate the timely detection and diagnosis of plant stress. As these biomarkers are conserved across different species of plants, this approach is species-agnostic. Minimally invasive electrochemical sensors can be used to interrogate the levels of these markers due to their electroactive nature. Salicylic acid (SA) is an ideal target as its associated with pathogen infection.[3
Minimally Invasive Platforms for Profiling Coral Reefs Associated Microorganisms
No full textThe extracellular calcification medium (ECM) of corals plays a crucial role in controlling the architecture of the calcium carbonate-based skeleton. The ECM is sandwiched between the skeleton and the epithelium and has a thickness that varies between a few nanometers to micrometers. Despite its importance in mediating the environmental resilience of corals, the majority of the studies conducted on the ECM are centered on characterizing its pH and ECM carbonate chemistry. While these parameters are crucial, they leave out the role of potential microbial colonies that may be present in the ECM. As the ECM is largely inaccessible, addressing this question has been difficult. To that end, we present an integrated microneedle device for the extraction of microbes from the ECM. The device is equipped with microneedle electrodes of varying shank heights that can simultaneously penetrate the coral tissue and identify ECM by way of in situ pH measurement. The microneedles are equipped with an open-side microfluidic channel for the extraction of the microbes and subsequent identification. Herein, we demonstrate the mechanical ability of the device to penetrate the Fungia and Bubble corals and determine the in vivo pH level of depths starting from 300 ?m up to 2 mm
Platforms for Monitoring and Remediation of Crops for Precision Farming
No full textPrecision farming (PF) has emerged as a transformative approach to optimizing agricultural practices by integrating real-time monitoring and targeted interventions. This thesis presents the development of plant-integrated sensing and delivery platforms that seek to enhance the efficiency, sustainability, and adaptability of modern agriculture. The work primarily focuses on the design and application of minimally invasive microneedle (MN)-based sensors for real-time plant health assessment, as well as phyto-injector systems for targeted agrochemical and genetic cargo delivery. These technologies offer novel solutions to longstanding challenges in crop monitoring and disease management. The MN-based sensors developed in this thesis provide a direct interface with plant tissues, enabling the continuous detection of key phytohormones and stress biomarkers such as salicylic acid (SA) and indole-3-acetic acid (IAA). By employing electrochemical and impedimetric sensing techniques, this platform achieves high sensitivity and specificity in monitoring physiological changes, allowing for early disease detection and precision treatment strategies. The incorporation of molecularly imprinted polymers (MIPs) further enhances the selectivity of these sensors, paving the way for broader applications in plant metabolomics. Additionally, this thesis introduces a phyto-injector system designed to facilitate the localized and controlled release of bioactive compounds. This platform provides a scalable and tunable method for agrochemical application and genetic modification, reducing environmental contamination and improving treatment efficacy. The phyto-injector’s validation using Agrobacterium-mediated transient gene expression demonstrates its potential for applications in plant biotechnology and stress adaptation research. The results of this work highlight the potential of integrating advanced sensing and delivery systems into PF frameworks, potentially improving resource efficiency and agricultural resilience. These advancements offer scalable and field-deployable solutions that can enhance yield predictions, reduce agrochemical dependency, and support sustainable farming practices. Future advancements in wireless connectivity and data integration will further extend the impact of these platforms to realize the potential of PF. This thesis, therefore, contributes a step toward the widespread adoption of precision-based plant monitoring and remediation technologies
Biocompatible 3D Printed Microneedles for Transdermal, Intradermal, and Percutaneous Applications
No full textMicroneedles (MNs) are playing an increasingly important role in biomedical applications, where minimally invasive methods are being developed that require imperceptible tissue penetration and drug delivery. To improve the integration of MNs in microelectromechanical devices, a high-resolution 3D printing technique is implemented. A reservoir with an array of hollow MNs is produced. The flow rate through the MNs is simulated and measured experimentally. The mechanical properties of the 3D printed material, such as elasticity modulus and yield strength, are investigated as functions of printing parameters, reaching maximum values of 1750.7 and 101.8 MPa, respectively. Analytical estimation of the MN buckling, fracture, and skin penetration forces is presented. Penetration tests of MNs into a skin-like material are conducted, where the piercing force ranges from 0.095 to 0.115 N, confirming sufficient stability of MNs. Furthermore, 200 and 400 μm-long MN arrays are used to successfully pierce and deliver into mouse skin with an average penetration depth of 100 and 180 μm, respectively. A biocompatibility assessment is performed, showing a high viability of HCT 116 cells cultured on top of the MN's material, making the developed MNs a very attractive solution for many biomedical applications.This work was funded and supported by King Abdullah University of Science and Technology (KAUST). The authors thank Dr. Simona Spinelli, Francesco Rottoli, and Stefano Pietro Mandaglio from the Animal Research Core Lab (ARCL) at KAUST for their assistance with the mouse piercing experiment
A Portable Device for Real-time Continuous Drug Monitoring in Freely Moving Small Animals
No full textThe large size and operational constraints of benchtop potentiostats, which typically require the use of anesthetized animals, have posed significant challenges for conducting real-time, long-term pharmacokinetic studies in freely moving subjects. This research addresses these challenges by developing a compact, portable electrochemical sensing platform capable of monitoring drug concentrations in real time within natural, dynamic environments. The system integrates lightweight, miniaturized electronics, and multiple electrochemical techniques with onboard data processing to eliminate the need for external computational support, while its energy-efficient design reduces reliance on large batteries. Experimental evaluations demonstrate that the device reliably measures drug concentrations using aptamer-based sensors and processes signals with baseline correction and drift compensation in situ. Unlike implantable systems, our externally mounted device offers the flexibility of quick attachment and replacement without surgical intervention, preserving animal welfare. These advancements open new avenues for pharmacokinetic research and closed-loop drug delivery systems by enabling continuous, high-frequency measurements in awake, freely moving small animals.The authors would like to acknowledge Abdullah Bukhamsin for his insightful discussions and valuable contributions to this work. We would also like to thank Professor Kevin W. Plaxco, Lisa C. Fetter, and Shaylee Larson for the opportunity to learn from them about aptamers, aptamer-based sensors, and their fabrication and development. This research was partially supported by King Abdullah University of Science and Technology through the Center of Excellence in Smart Health under award number 593
Biocompatible 3D Printed Microneedles for Transdermal, Intradermal, and Percutaneous Applications
No full textSynthesis of bimetallic (iron-cobalt) single atom catalysts for electrochemical detection of nitrites
No full textNitrite (NO2−) is responsible for several physiological processes but can be harmful in excess. With rising exposure from food preservatives, fertilizers, and pollutants, accurate nitrite assessment is crucial for health and environmental safety. Different methods have been employed for its determination, with electrochemical sensors showcasing great promise. Single atom catalysts (SACs) are a class of nanomaterials that consists of isolated catalytic metal atoms anchored on conductive supports, which exhibit unique electronic properties with great promise for this application. The performance of these materials can be enhanced even more by incorporating a secondary metal in the catalyst structure. This leads to the creation of more surface-active sites and enables the facilitation of multi-step reactions. Herein, a bimetallic single atom catalyst (FeCoSAN) is synthesized through a single step laser assisted solid-process by anchoring iron and cobalt atoms while simultaneously creating a laser-scribed graphene (LSG) support. The presence of Fe and Co atoms is verified by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption spectroscopy (XANES and EXAFS). Through electrochemical testing, the bimetallic system demonstrated excellent capabilities for determination of NO2, achieving up to 100% more efficiency, in comparison with bare LSG, with a detection limit of 2.42 µM and a sensitivity value of 515.07 µA mM−1 cm−2 over a linear range from 5.0 to 1666 µM. This highlights their potential for in vivo and point-of-care sensing applications
Advancing sensitivity with laser-scribed graphene interdigitated electrodes in water quality monitoring
No full textConventional methods for monitoring water quality are often time-consuming, expensive, and lack sensitivity, making it difficult to detect contaminants before they enter the environment. Therefore, it is essential to develop sensing platforms that address these issues and that are capable of performing on-site detection. As such, in this study, we developed an electrochemical sensing platform for detecting pharmaceutical pollutants in water, particularly paracetamol (PCM) and acetylsalicylic acid (ASP). By minimizing the gap distance between the working and auxiliary electrodes of laser-scribed graphene interdigitated electrodes (LSG-IDEs), the sensitivity of the sensors was improved. The developed platform was compared to a standard LSGE design, and the LSG-IDEs achieved an 18.6-fold and 70-fold improvement in detection limits for PCM and ASP, respectively. The system was tested with real wastewater samples spiked with ASP and PCM, demonstrating its effectiveness in practical scenarios. Additionally, the system was successfully integrated with an on-site detection device, demonstrating its potential for real-time, portable water quality monitoring. The high sensitivity and low-cost of LSG-IDEs make them a suitable option for the monitoring of water quality and protecting public health
