ZnO nanowire arrays exhibit cytotoxic distinction to cancer cells with different surface charge density: cytotoxicity is charge-dependent

Energy-Efficient and Effective MCF-7 Cell Ablation and Electrothermal Therapy Enabled by M13-WS2-PEG Nanostructures

Thermal agents (TAs) have exhibited promise in clinical tests when utilized in cancer thermal therapy (TT). While rapid degradation of TAs may address safety concerns, it limits the thermal stability required for effective treatment. TAs, which possess exceptional thermal stability, experience gradual deterioration. There are few approaches that effectively address the trade-off between improving thermal stability and simultaneously boosting material deterioration. Here, we control the thermal character of tungsten disulfide (WS2)-based 2D materials by utilizing an M13 phage through Joule heating (the M13-WS2-PEG nanostructures were generated and termed a tripartite (T) nanostructure), and developed a T nanostructure-driven TT platform (we called it T-TT) for efficient thermal ablation of clinically relevant MCF-7 cells. A relative cell viability of ~59% was achieved, as well as onset time of degradation of ~0.5 week. The T-TT platform also discloses an energy density of 5.9 J/mL. Furthermore, the phage-conjugated WS2 can be utilized to achieve ultrasound imaging for disease monitoring. Therefore, this research not only presents a thermal agent that overcomes TA limitations, but also demonstrates a practical application of WS2-type material system in ultra-energy efficient and effective cancer therapy.

Optically Triggering and Monitoring Single-Cell-Level Metabolism Using Ormosil-Decorated Ultrathin Fibers

The integration of biological components and artificial devices requires a bio-machine interface that can simultaneously trigger and monitor the activities in biosystems. Herein, we use an organically modified silicate (ormosil) composite coating containing a light-responsive nanocapsule and a fluorescent bioprobe for reactive oxygen species (ROS) to decorate ultrathin optical fibers, namely, ormosil-decorated ultrathin fibers (OD-UFs), and demonstrate that these OD-UFs can optically trigger and monitor the intracellular metabolism activities in living cells. The sizes and shapes of UF tips were finely controlled to match the dimension and mechanical properties of living cells. The increased elasticity of the ormosil coating of OD-UFs reduces possible mechanical damage during the cell membrane penetration. The light-responsive nanocapsule was physically absorbed on the surface of the ormosil coating and could release a stimulant to trigger the metabolism activities in cells upon the guided laser through OD-UFs. The fluorescent bioprobe was covalently linked with the ormosil matrix for monitoring the intracellular ROS generation, which was verified by the in vitro experiments on the microdroplets of a hydrogen peroxide solution. Finally, we found that the living cells could maintain most of their viability after being inserted with OD-UFs, and the intracellular metabolism activities were successfully triggered and monitored at the single-cell level. The OD-UF provides a new platform for the investigation of intracellular behaviors for drug stimulations and represents a new proof of concept for a bio-machine interface based on the optical and chemical activities of organic functional molecules.

WS2/Polyethylene Glycol Nanostructures for Ultra-Efficient MCF-7 Cancer Cell Ablation and Electrothermal Therapy

Developing novel nanostructures and advanced nanotechnologies for cancer treatment has attracted ever-increasing interest. Electrothermal therapy offers many advantages such as high efficiency and minimal invasiveness, but finding a balance between increasing stability of the nanostructure state and, at the same time, enhancing the nanostructure biodegradability presents a key challenge. Here, we modulate the biodegradation process of two-dimensional-material-based nanostructures by using polyethylene glycol (PEG) via nanostructure disrupt-and-release effects. We then demonstrate the development of a previously unreported alternating current (AC) pulse WS₂/PEG nanostructure system for enhancing therapeutic performance. A decrease in cell viability of ∼42% for MCF-7 cells with WS₂/PEG was achieved, which is above an average of ∼25% for current electrothermal-based therapeutic methods using similar energy densities, as well as degradation time of the WS₂ of ∼1 week, below an average of ∼3.5 weeks for state-of-the-art nanostructure-based systems in physiological media. Moreover, the incubation time of MCF-7 cells with WS₂/PEG reached ∼24 h, which is above the average of ∼4.5 h for current electrothermal-based therapeutic methods and with the use of the amount of time harnessed to incubate the cells with nanostructures before applying a stimulus as a measure of incubation time. Material characterizations further disclose the degradation of WS₂ and the grafting of PEG on WS₂ surfaces. These WS₂-based systems offer strong therapeutic performance and, simultaneously, maintain excellent biodegradability/biocompatibility, thus providing a promising route for the ablation of cancer.

Zinc oxide spiky nanoparticles: A promising nanomaterial for killing tumor cells

Zinc oxide (ZnO) nanostructures have been widely studied in biomedical fields due to their special properties. In recent years, ZnO spherical nanoparticles (SNPs) with nano-size as an anti-tumor agent have been widely concerned. While the effects of the non-spherical shaped ZnO nanoparticles on tumor cell death have been rarely reported. Here, we prepared ZnO spiky nanoparticles (SPNPs) as the research subject. We found that the SPNPs showed superiority in killing tumor cells. To be specific, SPNPs presented a long-term cytotoxicity effect on killing tumor cells, as plenty of SPNPs retained on the cell plasma membrane's exterior and still showed toxicity effect on tumor cells after co-incubation multiple times. Moreover, compared to SNPs, it was encouraging that SPNPs still showed stronger cytotoxicity in both simulated circulatory systems of tumor cells and 3D tumor cell spheroids. The stronger toxicity against tumor cells suggested that ZnO SPNPs have more advantages on killing tumor cells as a promising nanomedicine.

Bioelectricity, Its Fundamentals, Characterization Methodology, and Applications in Nano-Bioprobing and Cancer Diagnosis

Bioelectricity is an essential characteristic of a biological system that has played an important role in medical diagnosis particularly in cancer liquid biopsy. However, its biophysical origin and measurements have presented great challenges in experimental methodologies. For instance, in dynamic cell processes, bioelectricity cannot be accurately determined as a static electrical potential via electrophoresis. Cancer cells fundamentally differ from normal cells by having a much higher rate of glycolysis resulting in net negative charges on cell surfaces. The most recent investigations on cancer cell surface charge that is the direct bio-electrical manifestation of the "Warburg Effect," which can be directly monitored by specially designed nanoprobes, has been provided. The most up-to-date research results from charge-mediated cell targeting are reviewed. Correlations between the cell surface charge and cancer cell metabolism are established based on cell/probe electrostatic interactions. Bioelectricity is utilized not only as an analyte for investigation of the metabolic state of the cancer cells, but also applied in electrostatically and magnetically capturing of the circulating tumor cells from whole blood. Also reviewed is on the isolation of Candida albicans via bioelectricity-driven nanoparticle binding on fungus with surface charges.

Engineering Nanowire-Mediated Cell Lysis for Microbial Cell Identification

Researchers have demonstrated great promise for inorganic nanowire use in analyzing cells or intracellular components. Although a stealth effect of nanowires toward cell surfaces allows preservation of the living intact cells when analyzing cells, as a completely opposite approach, the applicability to analyze intracellular components through disrupting cells is also central to understanding cellular information. However, the reported lysis strategy is insufficient for microbial cell lysis due to the cell robustness and wrong approach taken so far ( i. e., nanowire penetration into a cell membrane). Here we propose a nanowire-mediated lysis method for microbial cells by introducing the rupture approach initiated by cell membrane stretching; in other words, the nanowires do not penetrate the membrane, but rather they break the membrane between the nanowires. Entangling cells with the bacteria-compatible and flexible nanowires and membrane stretching of the entangled cells, induced by the shear force, play important roles for the nanowire-mediated lysis to Gram-positive and Gram-negative bacteria and yeast cells. Additionally, the nanowire-mediated lysis is readily compatible with the loop-mediated isothermal amplification (LAMP) method because the lysis is triggered by simply introducing the microbial cells. We show that an integration of the nanowire-mediated lysis with LAMP provides a means for a simple, rapid, one-step identification assay (just introducing a premixed solution into a device), resulting in visual chromatic identification of microbial cells. This approach allows researchers to develop a microfluidic analytical platform not only for microbial cell identification including drug- and heat-resistance cells but also for on-site detection without any contamination.

Interfacing Inorganic Nanowire Arrays and Living Cells for Cellular Function Analysis

Inorganic nanowires are among the most attractive functional materials, which have emerged in the past two decades. They have demonstrated applications in information technology and energy conversion, but their utility in biological or biomedical research remains relatively under-explored. Although nanowire-based sensors have been frequently reported for biomolecular detection, interfacing nanowire arrays and living mammalian cells for the direct analysis of cellular functions is a very recent endeavor. Cell-penetrating nanowires enabled effective delivery of biomolecules, electrical and optical stimulation and recording of intracellular signals over a long period of time. Non-penetrating, high-density nanowire arrays display rich interactions between the nanostructured substrate and the micro/nanoscale features of cell surfaces. Such interactions enable efficient capture of rare cells including circulating tumor cells and trafficking leukocytes from complex biospecimens. It also serves as a platform for probing cell traction force and neuronal guidance. The most recent advances in the field that exploits nanowire arrays (both penetrating and non-penetrating) to perform rapid analysis of cellular functions potentially for disease diagnosis and monitoring are reviewed.