Dual-Color Optical Recording of Bioelectric Potentials by Polymer Electrochromism

Organic electro-scattering antenna: Wireless and multisite probing of electrical potentials with high spatial resolution

Monitoring electrical potentials with high recording site density and micrometer spatial resolution in liquid is critical in biosensing. Organic electronic materials have driven remarkable advances in the field because of their unique material properties, yet limitations in spatial resolution and recording density remain. Here, we introduce organic electro-scattering antennas (OCEANs) for wireless, light-based probing of electrical signals with micrometer spatial resolution, potentially from thousands of sites. The technology relies on the unique dependence of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate light scattering properties to its doping level. Electro-optic characteristics of individual antennas varying in diameters and operating voltages were systematically characterized in saline solution. Signal-to-noise ratios up to 48 were achieved in response to 100-mV stimuli, with 2.5-mV detection limits. OCEANs demonstrated millisecond time constants and exceptional long-term stability, enabling continuous recordings over 10 hours. By offering spatial resolution of 5 μm and a recording density of 4 × 106 cm-2, OCEANs unlock new readout capabilities, potentially accelerating fundamental and clinical research.

Advancing Intelligent Organ-on-a-Chip Systems with Comprehensive In Situ Bioanalysis

In vitro models are essential to a broad range of biomedical research, such as pathological studies, drug development, and personalized medicine. As a potentially transformative paradigm for 3D in vitro models, organ-on-a-chip (OOC) technology has been extensively developed to recapitulate sophisticated architectures and dynamic microenvironments of human organs by applying the principles of life sciences and leveraging micro- and nanoscale engineering capabilities. A pivotal function of OOC devices is to support multifaceted and timely characterization of cultured cells and their microenvironments. However, in-depth analysis of OOC models typically requires biomedical assay procedures that are labor-intensive and interruptive. Herein, the latest advances toward intelligent OOC (iOOC) systems, where sensors integrated with OOC devices continuously report cellular and microenvironmental information for comprehensive in situ bioanalysis, are examined. It is proposed that the multimodal data in iOOC systems can support closed-loop control of the in vitro models and offer holistic biomedical insights for diverse applications. Essential techniques for establishing iOOC systems are surveyed, encompassing in situ sensing, data processing, and dynamic modulation. Eventually, the future development of iOOC systems featuring cross-disciplinary strategies is discussed.

Transparent-to-Brown-Black Patterned Electrochromic Metal-Organic Frameworks

Metal-organic frameworks (MOFs) exhibit promising electrochromic (EC) performance owing to their porous structure, regular channel, and tunable component characteristics. However, few reports focus on MOF materials with the EC performance of a transparent to brown-black (neutral colored state) change that is more suitable for smart windows. In this work, we proposed a strategy for synthesizing MOF (named Ni-BPY) EC materials and corresponding films fabricated via a low-cost electrostatic spray deposition technique. The obtained film exhibits excellent EC performance with a neutral color change from transparent to brown-black, a large optical modulation of 70% at 430 nm, and a fast response within 10 s. Benefiting from good electrical and chemical stability, the Ni-BPY film can be cycled over 500 times. Notably, the Ni-BPY MOF film also delivers a stepwise-controlled process during the bleached state due to its porous characteristics. In addition, the unique color variation of the Ni-BPY film derives from the redox reaction of the Ni metal node between Ni2+ and Ni3+, which is verified by the in situ potential-dependent Raman and X-ray photoelectron spectroscopy (XPS) measurement. As a proof of application, the patterned Ni-BPY EC films and devices are additionally constructed to demonstrate their potential application in electronic tags and logo displays.

Nanotechnology and Cancer Bioelectricity: Bridging the Gap Between Biology and Translational Medicine

Bioelectricity is the electrical activity that occurs within living cells and tissues. This activity is critical for regulating homeostatic cellular function and communication, and disruptions of the same can lead to a variety of conditions, including cancer. Cancer cells are known to exhibit abnormal electrical properties compared to their healthy counterparts, and this has driven researchers to investigate the potential of harnessing bioelectricity as a tool in cancer diagnosis, prognosis, and treatment. In parallel, bioelectricity represents one of the means to gain fundamental insights on how electrical signals and charges play a role in cancer insurgence, growth, and progression. This review provides a comprehensive analysis of the literature in this field, addressing the fundamentals of bioelectricity in single cancer cells, cancer cell cohorts, and cancerous tissues. The emerging role of bioelectricity in cancer proliferation and metastasis is introduced. Based on the acknowledgement that this biological information is still hard to access due to the existing gap between biological findings and translational medicine, the latest advancements in the field of nanotechnologies for cellular electrophysiology are examined, as well as the most recent developments in micro- and nano-devices for cancer diagnostics and therapy targeting bioelectricity.

Compact Electrochromic Optical Recording of Bioelectric Potentials

Electrochromic optical recording (ECORE) is a label-free method that utilizes electrochromism to optically detect electrical signals in biological cells with a high signal-to-noise ratio and is suitable for long-term recording. However, ECORE usually requires a large and intricate optical setup, making it relatively difficult to transport and to study specimens on a large scale. Here, we present a Compact ECORE (CECORE) apparatus that drastically reduces the spatial footprint and complexity of the ECORE setup whilst maintaining high sensitivity. An autobalancing differential photodetector automates common-mode noise rejection, removing the need for manually adjustable optics, and a compact laser module conserves space compared to a typical laser mount. The result is a simple, easy-to-use, and relatively low cost system that achieves a sensitivity of 16.7 μV (within a factor of 5 of the shot noise limit), and reliably detects action potentials from Human-induced pluripotent stem cell (HiPSC) derived cardiomyocytes. This setup can be further improved to within 1.5 dB of the shot noise limit by filtering out power-line interference.

Soluble polymer facilely self-grown in situ on conducting substrates at room temperature towards electrochromic applications

Electrochromic polymer film preparation methods such as spin coating, spray coating, and electrochemical polymerization, are commonly used. At present, developing new film preparation technology is an important aspect in the field of electrochromics. Herein, a continuous in situ self-growing method based on the chemical reaction occurring on the surface of an ITO glass between a metal oxide and organic acid groups was successfully applied to prepare electrochromic polymer films at a mild room temperature. SEM, FT-IR spectroscopy, XPS, and XRD characterization methods were combined to reveal the process and mechanism of film formation. The following notable electrochromic properties were observed: switching time within 6 s, contrast reached 35%, and minimal decrease of stability after 600 cycles. Finally, the patterned films were obtained through the directional growth of polymers in solution. This study provides an effective strategy for designing and preparing electrochromic films by self-growing methods in future applications.

Multifunctional Biosensing Platform Based on Nickel-Modified Laser-Induced Graphene

Nickel plating electrolytes prepared by using a simple salt solution can achieve nickel plating on laser-induced graphene (LIG) electrodes, which greatly enhances the electrical conductivity, electrochemical properties, wear resistance, and corrosion resistance of LIG. This makes the LIG-Ni electrodes well suited for electrophysiological, strain, and electrochemical sensing applications. The investigation of the mechanical properties of the LIG-Ni sensor and the monitoring of pulse, respiration, and swallowing confirmed that the sensor can sense insignificant deformations to relatively large conformal strains of skin. Modulation of the nickel-plating process of LIG-Ni, followed by chemical modification, may allow for the introduction of glucose redox catalyst Ni2Fe(CN)6 with interestingly strong catalytic effects, which gives LIG-Ni impressive glucose-sensing properties. Additionally, the chemical modification of LIG-Ni for pH and Na+ monitoring also confirmed its strong electrochemical monitoring potential, which demonstrates application prospects in the development of multiple electrochemical sensors for sweat parameters. A more uniform LIG-Ni multi-physiological sensor preparation process provides a prerequisite for the construction of an integrated multi-physiological sensor system. The sensor was validated to have continuous monitoring performance, and its preparation process is expected to form a system for non-invasive physiological parameter signal monitoring, thus contributing to motion monitoring, disease prevention, and disease diagnosis.