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Optical stimulation technologies are gaining great consideration in cardiology, neuroscience studies, and drug discovery pathways by providing control over cell activity with high spatio-temporal resolution. However, this high precision requires manipulation of biological processes at genetic level concealing its development from broad scale application. Therefore, translating these technologies into tools for medical or pharmacological applications remains a challenge. Here, an all-optical nongenetic method for the modulation of electrogenic cells is introduced. It is demonstrated that plasmonic metamaterials can be used to elicit action potentials by converting near infrared laser pulses into stimulatory currents. The suggested approach allows for the stimulation of cardiomyocytes and neurons directly on commercial complementary metal-oxide semiconductor microelectrode arrays coupled with ultrafast pulsed laser, providing both stimulation and network-level recordings on the same device., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

3D vertical nanostructures have become one of the most significant methods for interfacing cells and the nanoscale and for accessing significant intracellular functionalities such as membrane potential. As this intracellular access can be induced by means of diverse cellular membrane poration mechanisms, it is important to investigate in detail the cell condition after membrane rupture for assessing the real effects of the poration techniques on the biological environment. Indeed, differences of the membrane dynamics and reshaping have not been observed yet when the membrane-nanostructure system is locally perturbed by, for instance, diverse membrane breakage events. In this work, new insights are provided into the membrane dynamics in case of two different poration approaches, optoacoustic- and electro-poration, both mediated by the same 3D nanostructures. The experimental results offer a detailed overview on the different poration processes in terms of electrical recordings and membrane conformation., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The dynamic interface between the cellular membrane and 3D nanostructures determines biological processes and guides the design of novel biomedical devices. Despite the fact that recent advancements in the fabrication of artificial biointerfaces have yielded an enhanced understanding of this interface, there remain open questions on how the cellular membrane reacts and behaves in the presence of sharp objects on the nanoscale. Here we provide a multifaceted characterization of the cellular membrane's mechanical stability when closely interacting with high-aspect-ratio 3D vertical nanostructures, providing strong evidence that vertical nanostructures spontaneously penetrate the cellular membrane to form a steady intracellular coupling only in rare cases and under specific conditions. The cell membrane is able to conform tightly over the majority of structures with various shapes while maintaining its integrity.

Plasmonic nanostructures capable of converting light to heat have found wide applications, thus giving rise to the field of thermoplasmonics. Among them, the use of gold-based plasmonic structures in near-infrared (NIR) spectral regions has catalyzed substantial research efforts due to the potential impact in clinical therapy applications. However, the photon scattering effect scaling with the square of the nanoparticle volume leads to high scattering and then low absorption efficiency. This limit has hindered the exploitation of gold nanoparticles, especially in NIR II regions above 1000 nm. Here, we make a step forward for overcoming this limitation by introducing hyperbolic metamaterial nanoparticles that are made of multi-layered gold/dielectric nanodisks and exhibit >70% absorption efficiency in the NIR II and III regions. Their high light-to-heat conversion is demonstrated by a much larger temperature increase than that of gold nanodisks with the same amount of gold. Efficient in vitro hyperthermia of living cells with negligible cytotoxicity shows the potential of our platform for versatile bio-medical applications. [ABSTRACT FROM AUTHOR]

Biological studies on in vitro cell cultures are of fundamental importance to investigate cell response to external stimuli, such as new drugs for the treatment of specific pathologies, or to study communication between electrogenic cells. Although three-dimensional (3D) nanostructures brought tremendous improvements on biosensors used for various biological in vitro studies, including drug delivery and electrical recording, there is still a lack of multifunctional capabilities that could help gain deeper insights in several bio-related research fields. In this work, the electrical recording of large cell ensembles and the intracellular delivery of few selected cells are combined on the same device by integrating microfluidic channels on the bottom of a multi-electrode array decorated with 3D hollow nanostructures. The novel platform allows the recording of intracellular-like action potentials from large ensembles of cardiomyocytes derived from human induced pluripotent stem cells (hiPSC) and from the HL-1 line, while different molecules are selectively delivered into single/few targeted cells. The proposed approach shows high potential for enabling new comprehensive studies that can relate drug effects to network level cell communication processes. [ABSTRACT FROM AUTHOR]

Three-dimensional nanostructures are becoming the standard tools for interfacing cells with biosensors and other devices. A morphology that develops in three dimensions leads to the engulfment of the nanostructures by the cell, reducing the cleft and largely improving the cell/material coupling and sealing. The recording of action potentials from electrogenic cells, as well as biomolecular sensing of generic biological samples, can benefit from 3D nano-objects due to the improved bio-interface. In this context, we present here a novel fabrication technique for producing 3D vertical nanostructures that can be tuned both in material composition and shape, being thus suitable for a large variety of applications, from SERS spectroscopy and microfluidics to intracellular recording. The technique is based on focus ion beam milling and gold electrodeposition. This combination allows to fabricate coaxial-like nanocylinders with a metallic core and an insulating shell. Moreover, the metallic core can be structured as a hollow donut to act as nano-channel, or as a bulky head to increase the contact surface. The nanostructure coupling with cells is evaluated by fluorescence imaging, SERS spectroscopy and FIB/SEM cross-section imaging of HL-1 cardiac cells cultured on the devices. [ABSTRACT FROM AUTHOR]