Electrochemical Sensing Directions for Next-Generation Healthcare: Trends, Challenges, and Frontiers.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9605918

Towards hospital-on-chip supported by 2D MXenes-based 5th generation intelligent biosensors

Three-dimensional cell cultures using patient-derived stem cells are essential in vitro models for a more efficient and individualized cancer therapy. Currently, culture conditions and metabolite concentrations, especially hypoxia, are often not accessible continuously and in situ within microphysiological systems. However, understanding and standardizing the cellular microenvironment are the key to successful in vitro models. We developed a microfluidic organ-on-chip platform for matrix-based, heterogeneous 3D cultures with fully integrated electrochemical chemo- and biosensor arrays for the energy metabolites oxygen, lactate, and glucose. Advanced microstructures allow straightforward cell matrix integration with standard laboratory equipment, compartmentalization, and microfluidic access. Single, patient-derived, triple-negative breast cancer stem cells develop into tumour organoids in a heterogeneous spheroid culture on-chip. Our system allows unprecedented control of culture conditions, including hypoxia, and simultaneous verification by integrated sensors. Beyond previous works, our results demonstrate precise and reproducible on-chip multi-analyte metabolite monitoring under dynamic conditions from a matrix-based culture over more than one week. Responses to alterations in culture conditions and cancer drug exposure, such as metabolite consumption and production rates, could be accessed quantitatively and in real-time, in contrast to endpoint analyses. Our approach highlights the importance of continuous, in situ metabolite monitoring in 3D cell cultures regarding the standardization and control of culture conditions, and drug screening in cancer research. Overall, the results underline the potential of microsensors in organ-on-chip systems for successful application, e.g. in personalized medicine. 

/pdf/microfluidic-organ-on-chip-system-for-multi-analyte-2x6jv0rf.pdf

Microfluidic organ-on-chip system for multi-analyte monitoring of metabolites in 3D cell cultures

Three-dimensional cell cultures using patient-derived stem cells are essential in vitro models for a more efficient and individualized cancer therapy. Currently, culture conditions and metabolite concentrations, especially hypoxia, are often not accessible continuously and in situ within microphysiological systems. However, understanding and standardizing the cellular microenvironment are the key to successful in vitro models. We developed a microfluidic organ-on-chip platform for matrix-based, heterogeneous 3D cultures with fully integrated electrochemical chemo- and biosensor arrays for the energy metabolites oxygen, lactate, and glucose. Advanced microstructures allow straightforward cell matrix integration with standard laboratory equipment, compartmentalization, and microfluidic access. Single, patient-derived, triple-negative breast cancer stem cells develop into tumour organoids in a heterogeneous spheroid culture on-chip. Our system allows unprecedented control of culture conditions, including hypoxia, and simultaneous verification by integrated sensors. Beyond previous works, our results demonstrate precise and reproducible on-chip multi-analyte metabolite monitoring under dynamic conditions from a matrix-based culture over more than one week. Responses to alterations in culture conditions and cancer drug exposure, such as metabolite consumption and production rates, could be accessed quantitatively and in real-time, in contrast to endpoint analyses. Our approach highlights the importance of continuous, in situ metabolite monitoring in 3D cell cultures regarding the standardization and control of culture conditions, and drug screening in cancer research. Overall, the results underline the potential of microsensors in organ-on-chip systems for successful application, e.g. in personalized medicine.

Microfluidic organ-on-chip system for multi-analyte monitoring of metabolites in 3D cell cultures.

Organ-like cell clusters, so-called organoids, which exhibit self-organized and similar organ functionality as the tissue of origin, have provided a whole new level of bioinspiration for ex vivo systems Microfluidic organoid or organs-on-a-chip platforms are a new group of micro-engineered promising models that recapitulate 3D tissue structure and physiology and combines several advantages of current in vivo and in vitro models Microfluidics technology is used in numerous applications since it allows us to control and manipulate fluid flows with a high degree of accuracy This system is an emerging tool for understanding disease development and progression, especially for personalized therapeutic strategies for cancer treatment, which provide well-grounded, cost-effective, powerful, fast, and reproducible results In this review, we highlight how the organoid-on-a-chip models have improved the potential of efficiency and reproducibility of organoid cultures More widely, we discuss current challenges and development on organoid culture systems together with microfluidic approaches and their limitations Finally, we describe the recent progress and potential utilization in the organs-on-a-chip practice

Microfluidic Organoids-on-a-Chip: Quantum Leap in Cancer Research.

In recent decades, three-dimensional (3D) cancer cell models have attracted increasing interest in the field of drug screening due to their significant advantages in more accurate simulations of heterogeneous tumor behavior in vivo compared to two-dimensional models. Furthermore, drug sensitivity testing based on 3D cancer cell models can provide more reliable in vivo efficacy prediction. The gold standard fluorescence staining is hard to achieve real-time and label-free viability monitoring in 3D cancer cell models. In this study, a microgroove impedance sensor (MGIS) was specially developed for the dynamic and noninvasive monitoring of 3D cell viability. 3D cancer cells were trapped in microgrooves with gold electrodes on opposite walls for in situ impedance measurement. The change in the number of live cells caused inversely proportional changes to the impedance magnitude of the entire cell/Matrigel construct and reflected the proliferation and apoptosis of the 3D cells. It was confirmed that the 3D cell viability detected by the MGIS was highly consistent with the standard live/dead staining by confocal microscope characterization. Furthermore, the accuracy of the MGIS was validated quantitatively using a 3D lung cancer model and sophisticated drug sensitivity testing. In addition, the parameters of the MGIS in the measurement experiments were optimized in detail using simulations and experimental validation. The results demonstrated that the MGIS coupled with 3D cell culture would be a promising platform to improve the efficiency and accuracy of cell-based anticancer drug screening in vitro. A new micro groove impedance sensor enables the real-time and high-throughput analysis of 3D lung cancer cell models. In-vitro cell-based assays are important for the screening of new cancer drugs. However, many drug screening approaches only work for 2D arrangements of cells, yet it is known that 3D arrangements can behave very differently. Electrochemical impedance spectroscopy is widely used for monitoring the behavior of 2D arrangements of cells, yet attempts to extend it to 3D are limited. Now, a team led by Ping Wang from Zhejiang University demonstrate a micro groove impedance sensor for drug screening of 3D cancer cell models. Substantial differences were seen compared to 2D analysis, demonstrating the importance of tools for assessing 3D cancer models in drug development.

/pdf/3d-microgroove-electrical-impedance-sensing-to-examine-3d-293qechsn5.pdf

3D microgroove electrical impedance sensing to examine 3D cell cultures for antineoplastic drug assessment

Metabolism is a common biological mechanism in living cells. Acidification plays an important role in cell metabolism, in which the extracellular pH change is used to indicate the vitality of cells. For extracellular detection of cell metabolic substances, light addressable potentiometric sensor (LAPS) has many advantages, such as high sensitivity, easy encapsulation, and convenient integration with microfluidic system for cell experiments. LAPS is a spatially resolved biochemical sensor based on field-effect. In this work, we present a microfluidic system integrated with LAPS for real-time extracellular acidification rate (ECAR) detection. The functions of traditional microphysiometer are achieved with simpler structure devices. Polydimethylsiloxane (PDMS) chamber was manufactured for cell culture, and microfluidic flow paths were used for medium and drug delivery. A bubble trap device was applied to eliminate air bubbles generated in microfluidics. Characteristic tests and cell metabolism experiments were carried out to determine the performance of LAPS by monitoring the pH change of hepatoma HepG2 cells. Glucose and doxorubicin were delivered to the cell chamber to verify the effects of the drug. The pH sensitivity of LAPS is 335.5 nA/pH at the working point in constant voltage mode. The ECAR of HepG2 cells was -48.53 mpH/min in normal glucose medium (25 mM), and it changed to -114.42 mpH/min in high glucose medium (125 mM) and -17.88 mpH/min under the effect of doxorubicin (10 μM). The results show that the microfluidic LAPS presents good performance in real-time detection of cell acidification and provides a convenient means of assessing cellular specificity of drugs. The modular structure and high expandability make the microfluidic LAPS has good potential in the application of organ-on-chip.

Microfluidic chip system integrated with light addressable potentiometric sensor (LAPS) for real-time extracellular acidification detection

2D MXene-Ti3C2Tχ has demonstrated promising application prospects in various fields; however, it fails to function properly in biosensor setups due to restacking and anodic oxidation problems. To expand beyond these existing limitations, an effective strategy to for modifying the MXene by covalently grafting first-generation poly(amidoamine) dendrimers onto an MXene in situ (MXene@PAMAM) was reported herein. When used as a conjugated template, the MXene not only preserved the high conductivity but also conferred a specific 2D architecture and large specific surface areas for anchoring PAMAM. The PAMAM, an efficient spacer and stabilizer, simultaneously suppressed the substantial restacking and oxidation of the MXene, which endowed this hybrid with improved electrochemical performance compared to that of the bare MXene in terms of favorable conductivity and stability under anodic potential. Moreover, the massive amino terminals of PAMAM offer abundant active sites for adsorbing Au nanoparticles (AuNPs). The resulting 3D hierarchical nanoarchitecture, AuNPs/MXene@PAMAM, had advanced structural merits that led to its superior electrochemical performance in biosensing. As a proof of concept, this MXene@PAMAM-based nanobiosensing platform was applied to develop an immunosensor for detecting human cardiac troponin T (cTnT). A fast, sensitive, and highly selective response toward the target in the presence of a [Fe(CN)6]3-/4- redox marker was realized, ensuring a wide detection of 0.1-1000 ng/mL with an LOD of 0.069 ng/mL. The sensor's signal only decreased by 4.38% after 3 weeks, demonstrating that it exhibited satisfactory stability and better results than previously reported MXene-based biosensors. This work has potential applicability in the bioanalysis of cTnT and other biomarkers and paves a new path for fabricating high-performance MXenes for biomedical applications and electrochemical engineering. 

/pdf/covalently-grafting-first-generation-pamam-dendrimers-onto-1awsbc8w.pdf

Covalently grafting first-generation PAMAM dendrimers onto MXenes with self-adsorbed AuNPs for use as a functional nanoplatform for highly sensitive electrochemical biosensing of cTnT

A light-addressable potentiometric sensor (LAPS) is a semiconductor electrochemical sensor based on the field-effect which detects the variation of the Nernst potential on the sensor surface, and the measurement area is defined by illumination. Thanks to its light-addressability feature, an LAPS-based chemical imaging sensor system can be developed, which can visualize the two-dimensional distribution of chemical species on the sensor surface. This sensor system has been used for the analysis of reactions and diffusions in various biochemical samples. In this review, the LAPS system set-up, including the sensor construction, sensing and substrate materials, modulated light and various measurement modes of the sensor systems are described. The recently developed technologies and the affecting factors, especially regarding the spatial resolution and temporal resolution are discussed and summarized, and the advantages and limitations of these technologies are illustrated. Finally, the further applications of LAPS-based chemical imaging sensors are discussed, where the combination with microfluidic devices is promising.

https://www.mdpi.com/1424-8220/19/19/4294/pdf

Recent Developments of High-Resolution Chemical Imaging Systems Based on Light-Addressable Potentiometric Sensors (LAPSs).

/pdf/covalently-grafting-first-generation-pamam-dendrimers-onto-2z8j8w73.pdf

Yong Qiu

Papers

3D microgroove electrical impedance sensing to examine 3D cell cultures for antineoplastic drug assessment

Microfluidic chip system integrated with light addressable potentiometric sensor (LAPS) for real-time extracellular acidification detection

Covalently grafting first-generation PAMAM dendrimers onto MXenes with self-adsorbed AuNPs for use as a functional nanoplatform for highly sensitive electrochemical biosensing of cTnT

Recent Developments of High-Resolution Chemical Imaging Systems Based on Light-Addressable Potentiometric Sensors (LAPSs).

Covalently grafting first-generation PAMAM dendrimers onto MXenes with self-adsorbed AuNPs for use as a functional nanoplatform for highly sensitive electrochemical biosensing of cTnT