Self-powered, light-controlled, bioresorbable platforms for programmed drug delivery

TREM2 scFv-Engineering Escherichia coli Displaying Modulation of Macrophages to Boost Cancer Radio-Immunotherapy

Preoperative neoadjuvant radio-chemotherapy is a cornerstone in the treatment of low rectal cancer, yet its effectiveness can be limited by the insensitivity of some patients, profoundly impacting their quality of life. Through preliminary research, it is found that TREM2+ macrophages play a pivotal role in the non-responsiveness to immunotherapy. To address this challenge, a novel ionizing radiation-responsive delivery system is developed for the precise expression of anti-TREM2 single-chain antibody fragments (scFv) using an engineered probiotic, Escherichia coli Nissle 1917 (EcN), to modulate immunotherapy. The released anti-TREM2 scFv can be precisely targeted and delivered to the tumor site via the engineered EcN outer membrane vesicles (OMVs), thereby reversing the immunosuppressive tumor microenvironment and enhancing tumor therapeutic efficiency when used in combination with the αPD-L1 immune checkpoint inhibitor. Additionally, these engineered bacteria can be further modified to enhance the intestinal colonization capabilities through oral administration, thereby regulating the gut microbiota and its metabolic byproducts. Consequently, the ionizing radiation-responsive drug delivery system based on the engineered bacteria not only introduces a promising new therapeutic option for low rectal cancer but also showcases the potential to finely tune immune responses within the intricate tumor microenvironment, paving the way for innovative strategies in tumor radio-immunotherapy.

Self-powered biomedical devices: biology, materials, and their interfaces

Integrating biomedical electronic devices holds profound promise for advancements in healthcare and enhancing individuals' quality of life. However, the persistent challenges associated with the traditional batteries' limited lifespan and bulkiness hinder these devices' long-term functionality and consistent power supply. Here, we delve into the biology and material interfaces in self-powered medical devices by summarizing the intrinsic electric demands in humans, analyzing material and biological mechanisms for electricity generation and storage, and discussing the pathways toward self-chargeable powering. As a result, the current challenges in material designs and biological integrations emerged to shape the future directions in advancing self-powered medical devices. This paper calls on the community to integrate biology and material science to develop self-powering medical devices and improve their clinical prospects.

Ionic Diode-Based Drug Delivery System

Drug delivery systems hold promise for delivering cytotoxic drugs by controlling the timing and location of the drug release. However, conventional delivery mechanisms often fall short of achieving spatiotemporally controlled yet sustained release, which is crucial for ensuring drug efficacy and minimizing impact on surrounding tissues. Here, an ionic diode-based drug delivery system is reported that is controlled by an electric potential and capable of releasing drugs at scales ranging from nanogram to microgram. The migrated drug is slowly but continuously diffused to the lesion through the hydrogel at the desired rate. The ionic diode provides flow-free drug delivery while minimizing unintended drug leakage over prolonged periods. Implanted in a freely moving tumor-bearing mouse model, the system filled with doxorubicin demonstrated superior anti-tumor efficacy and minimal off-target immune toxicity compared to the intratumoral injection of free doxorubicin. With its mechanically compliant and biocompatible components, the system offers a safe and readily translatable approach to patients with surgically unresectable tumors.

Advances in integrated power supplies for self-powered bioelectronic devices

Bioelectronic devices with medical functions have attracted widespread attention in recent years. Power supplies are crucial components in these devices, which ensure their stable operation. Biomedical devices that utilize external power supplies and extended electrical wires limit patient mobility and increase the risk of discomfort and infection. To address these issues, self-powered devices with integrated power supplies have emerged, including triboelectric nanogenerators, piezoelectric nanogenerators, thermoelectric generators, batteries, biofuel cells, solar cells, wireless power transfer, and hybrid energy systems. This mini-review highlights the recent advances in the power supplies utilized in these self-powered devices. A concluding section discusses the subsisting challenges and future perspectives in integrated power supply technologies and design and manufacturing of self-powered devices.

Wirelessly Actuated Microfluidic Pump and Valve for Controlled Liquid Delivery in Dental Implants

Enabling minimally invasive and precise control of liquid release in dental implants is crucial for therapeutic functions such as delivering antibiotics to prevent biofilm formation, infusing stem cells to promote osseointegration, and administering other biomedicines. However, achieving controllable liquid cargo release in dental implants remains challenging due to the lack of wireless and miniaturized fluidic control mechanisms. Here wireless miniature pumps and valves that allow remote activation of liquid cargo delivery in dental implants, actuated and controlled by external magnetic fields (<65 mT), are reported. A magnet-screw mechanism in a fluidic channel to function as a piston pump, alongside a flexible magnetic valve designed to open and close the fluidic channel, is proposed. The mechanisms are showcased by storing and releasing of liquid up to 52 µL in a dental implant. The liquid cargos are delivered directly to the implant-bone interface, a region traditionally difficult to access. On-demand liquid delivery is further showed by a metal implant inside both dental phantoms and porcine jawbones. The mechanisms are promising for controllable liquid release after implant placement with minimal invasion, paving the way for implantable devices that enable long-term and targeted delivery of therapeutic agents in various bioengineering applications.

Wearable and implantable biosensors: mechanisms and applications in closed-loop therapeutic systems

This review article examines the current state of wearable and implantable biosensors, offering an overview of their biosensing mechanisms and applications. We also delve into integrating these biosensors with therapeutic systems, discussing their operational principles and incorporation into closed-loop devices. Biosensing strategies are broadly categorized into chemical sensing for biomarker detection, physical sensing for monitoring physiological conditions such as pressure and temperature, and electrophysiological sensing for capturing bioelectrical activities. The discussion extends to recent developments in drug delivery and electrical stimulation devices to highlight their significant role in closed-loop therapy. By integrating with therapeutic devices, biosensors enable the modulation of treatment regimens based on real-time physiological data. This capability enhances the patient-specificity of medical interventions, an essential aspect of personalized healthcare. Recent innovations in integrating biosensors and therapeutic devices have led to the introduction of closed-loop wearable and implantable systems capable of achieving previously unattainable therapeutic outcomes. These technologies represent a significant leap towards dynamic, adaptive therapies that respond in real-time to patients' physiological states, offering a level of accuracy and effectiveness that is particularly beneficial for managing chronic conditions. This review also addresses the challenges associated with biosensor technologies. We also explore the prospects of these technologies to address their potential to transform disease management with more targeted and personalized treatment solutions.

Soft and Flexible Bioelectronic Micro-Systems for Electronically Controlled Drug Delivery

The concept of targeted and controlled drug delivery, which directs treatment to precise anatomical sites, offers benefits such as fewer side effects, reduced toxicity, optimized dosages, and quicker responses. However, challenges remain to engineer dependable systems and materials that can modulate host tissue interactions and overcome biological barriers. To stay aligned with advancements in healthcare and precision medicine, novel approaches and materials are imperative to improve effectiveness, biocompatibility, and tissue compliance. Electronically controlled drug delivery (ECDD) has recently emerged as a promising approach to calibrated drug delivery with spatial and temporal precision. This article covers recent breakthroughs in soft, flexible, and adaptable bioelectronic micro-systems designed for ECDD. It overviews the most widely reported operational modes, materials engineering strategies, electronic interfaces, and characterization techniques associated with ECDD systems. Further, it delves into the pivotal applications of ECDD in wearable, ingestible, and implantable medical devices. Finally, the discourse extends to future prospects and challenges for ECDD.

On-demand drug delivery bioelectronics through a water-processable low dimensional highly conductive MXene layer

On-demand drug delivery holds great promise to optimize pharmaceutical efficacy while minimizing the side effects. However, existing on-demand drug delivery systems often require complicated manufacturing processes that preclude their wide implementation of a broad range of drugs. In this work, we demonstrate the introduction of MXene-coated microneedles (MNs) into bioelectronics for digitally controllable gate-valve drug delivery. MXenes, featuring high electronic conductivity, excellent biocompatibility, and solution processibility, enable low-cost scalability for printable bioelectronics. In an electrolytic state (e.g., body fluid), the coated MXene is oxidized and desorbed due to redox reactions caused by electrical bias, allowing the underlying drug to be controllably released. The MXene-incorporated drug delivery system not only demonstrates excellent biocompatibility and operational stability, but also features low-cost construction and sustainable usage. Besides, these MXene-coated MNs allow both on-demand transformation and local-region customization, further increasing the structural versatility and capability of multidrug delivery systems.

Electrically Powered Dissipative Hydrogel Networks Reveal Transient Stiffness Properties for Out-of-Equilibrium Operations

Living systems use dissipative processes to enable precise spatiotemporal control over various functions, including the transient modulation of the stiffness of tissues, which, however, is challenging to achieve in soft materials. Here, we report a new platform to program hydrogel films with tunable, time-dependent mechanical properties under out-of-equilibrium conditions, powered by electricity. We show that the lifetime of the transient network of a surface-confined hydrogel film can be effectively controlled by programming the generation of an electrochemically oxidized mediator in the presence of a chemical or photoreducing agent in solution. It is, therefore, electrically possible to direct the transient stiffening or softening of the hydrogel film, enabling high modularity of the material functions with precise spatiotemporal control. Temporally controlled operations of the hydrogel films are demonstrated for the on-demand, dose-controlled release of multiple model protein payloads from electrode arrays using the present electrically powered dissipative system. This demonstration of electrically driven transient modulation of the stiffness properties of hydrogel films represents an important step toward the engineering of dissipative materials for developing future biomedical applications that can harness the temporal, adaptive properties of this new class of materials.

A soft implantable energy supply system that integrates wireless charging and biodegradable Zn-ion hybrid supercapacitors

The advent of implantable bioelectronic devices offers prospective solutions toward health monitoring and disease diagnosis and treatments. However, advances in power modules have lagged far behind the tissue-integrated sensor nodes and circuit units. Here, we report a soft implantable power system that monolithically integrates wireless energy transmission and storage modules. The energy storage unit comprises biodegradable Zn-ion hybrid supercapacitors that use molybdenum sulfide (MoS2) nanosheets as cathode, ion-crosslinked alginate gel as electrolyte, and zinc foil as anode, achieving high capacitance (93.5 mF cm-2) and output voltage (1.3 V). Systematic investigations have been conducted to elucidate the charge storage mechanism of the supercapacitor and to assess the biodegradability and biocompatibility of the materials. Furthermore, the wirelessly transmitted energy can not only supply power directly to applications but also charge supercapacitors to ensure a constant, reliable power output. Its power supply capabilities have also been successfully demonstrated for controlled drug delivery.

Advances in Bioresorbable Materials and Electronics

Transient electronic systems represent an emerging class of technology that is defined by an ability to fully or partially dissolve, disintegrate, or otherwise disappear at controlled rates or triggered times through engineered chemical or physical processes after a required period of operation. This review highlights recent advances in materials chemistry that serve as the foundations for a subclass of transient electronics, bioresorbable electronics, that is characterized by an ability to resorb (or, equivalently, to absorb) in a biological environment. The primary use cases are in systems designed to insert into the human body, to provide sensing and/or therapeutic functions for timeframes aligned with natural biological processes. Mechanisms of bioresorption then harmlessly eliminate the devices, and their associated load on and risk to the patient, without the need of secondary removal surgeries. The core content focuses on the chemistry of the enabling electronic materials, spanning organic and inorganic compounds to hybrids and composites, along with their mechanisms of chemical reaction in biological environments. Following discussions highlight the use of these materials in bioresorbable electronic components, sensors, power supplies, and in integrated diagnostic and therapeutic systems formed using specialized methods for fabrication and assembly. A concluding section summarizes opportunities for future research.