Wireless electrical-molecular quantum signalling for cancer cell apoptosis.

Quantum biological tunnelling for electron transfer is involved in controlling essential functions for life such as cellular respiration and homoeostasis. Understanding and controlling the quantum effects in biology has the potential to modulate biological functions. Here we merge wireless nano-electrochemical tools with cancer cells for control over electron transfer to trigger cancer cell death. Gold bipolar nanoelectrodes functionalized with redox-active cytochrome c and a redox mediator zinc porphyrin are developed as electric-field-stimulating bio-actuators, termed bio-nanoantennae. We show that a remote electrical input regulates electron transport between these redox molecules, which results in quantum biological tunnelling for electron transfer to trigger apoptosis in patient-derived cancer cells in a selective manner. Transcriptomics data show that the electric-field-induced bio-nanoantenna targets the cancer cells in a unique manner, representing electrically induced control of molecular signalling. The work shows the potential of quantum-based medical diagnostics and treatments.

Electrochemical Immunosensor for Ultra-Low Detection of Human Papillomavirus Biomarker for Cervical Cancer.

Human papillomavirus (HPV) is the causative agent for cervical cancer. Of the various types of HPV, the high-risk HPV-16 type is the most important antigenic high-risk HPV. In this work, the antigenic HPV-16 L1 peptide was immobilized on a glassy carbon electrode and used to detect several concentrations of the anti-HPV-16 L1 antibody, and vice versa. Two electrode platforms were used: onion-like carbon (OLC) and its polyacrylonitrile (OLC-PAN) composites. Both platforms gave a wide linear concentration range (1.95 fg/mL to 6.25 ng/mL), excellent sensitivity (>5.2 µA/log ([HPV-16 L1, fg/mL]), and extra-ordinarily low limit of detection (LoD) of 1.83 fg/mL (32.7 aM) and 0.61 fg/mL (10.9 aM) for OLC-PAN and OLC-based immunosensors, respectively. OLC-PAN modified with the HPV-16 L1 protein showed low LoD for the HPV-16 L1 antibody (2.54 fg/mL, i.e., 45.36 aM), proving its potential use for screening purposes. The specificity of detection was proven with the anti-ovalbumin antibody (anti-OVA) and native ovalbumin protein (OVA). An immobilized antigenic HPV-16 L1 peptide showed insignificant interaction with anti-OVA in contrast with the excellent interaction with anti-HPV-16 L1 antibody, thus proving high specificity. The application of the immunosensor as a potential point-of-care (PoC) diagnostic device was investigated with screen-printed carbon electrodes, which detected ultra-low (ca. 0.7 fg/mL ≈ 12.5 aM) and high (ca. 12 µg/mL ≈ 0.21 µM) concentrations. This study represents the lowest LoD reported for HPV-16 L1. It opens the door for further investigation with other electrode platforms and realization of PoC diagnostic devices for screening and testing of HPV biomarkers for cervical cancer.

Biocompatible metallosurfactant-based nanocolloid-loaded Rose Bengal with excellent singlet oxygen-induced phototoxicity efficiency against cancer cells.

Photodynamic therapy (PDT) is facing challenges such as poor solubility, precise delivery, self-aggregation, and photobleaching of photosensitizers with cancer cells due to their less tendency to accumulate in tumor tissues. To address these challenges, we have explored a Rose Bengal (RB)-loaded metallocatanionic vesicles (MCVs) nanosystem for the phototoxicity of cancer cells. Different sets of MCVs were prepared by two different cationic single-chain metallosurfactants, i.e., hexadecylpyridinium trichlorocuprate (CuCPC I) and hexadecylpyridinium trichloroferrate (FeCPC I) in combination with anionic double-chain sodium bis(2-ethylhexyl)sulfosuccinate (AOT) surfactant in phosphate buffer saline of pH 7.4. The RB-loaded CuCPC I:AOT and FeCPC I:AOT vesicles enhanced the maximum singlet oxygen (1O2) generation by 1-fold and 3-fold, respectively, compared to pure RB. Upon irradiation with a 532 nm laser for 10 min, these RB-loaded CuCPC I:AOT and FeCPC I:AOT MCVs significantly decreased the metabolic activity of U-251 cells by 70% and 85% at MCVs concentration of 0.75 µM, respectively. Furthermore, RB-loaded MCVs showed the highest intracellular 1O2-mediated membrane damage and cell-killing effect as confirmed by singlet oxygen sensor green and differential nuclear staining assay, which is attributed to the cellular uptake profile of different RB-loaded MCVs fractions. Caspase 3/7 assay confirmed the apoptotic pathway of cell death by activating caspase. Therefore, the photoactivation of RB-loaded MCVs led to a significant reduction in the viability of U-251 cells (maximum 85%), which resulted in cell death. Our study demonstrated the advantage of using these dual-charge and biocompatible metallocatanionic vesicles as a promising delivery system of photodynamic therapy that can enhance 1O2 generation from PS and can be further utilized in photomedicine.

Electric field responsive nanotransducers for glioblastoma.

BACKGROUND: Electric field therapies such as Tumor Treating Fields (TTFields) have emerged as a bioelectronic treatment for isocitrate dehydrogenase wild-type and IDH mutant grade 4 astrocytoma Glioblastoma (GBM). TTFields rely on alternating current (AC) electric fields (EF) leading to the disruption of dipole alignment and induced dielectrophoresis (DEP) during cytokinesis. Although TTFields have a favourable side effect profile, particularly compared to cytotoxic chemotherapy, survival benefits remain limited (~ 4.9 months) after an extensive treatment regime (20 hours/day for 18 months). The cost of the technology also limits its clinical adoption worldwide. Therefore, the discovery of new technology that can enhance both the therapeutic efficiency and efficacy of these TTFields will be of great benefit to cancer treatment and decrease healthcare costs worldwide. METHODS: In this work, we report the role of electrically conductive gold (GNPs), dielectric silica oxide (SiO2), and semiconductor zinc oxide (ZnO) nanoparticles (NPs) as transducers for enhancing EF mediated anticancer effects on patient derived GBM cells. Physicochemical properties of these NPs were analyzed using spectroscopic, electron microscopy, and light-scattering techniques. RESULTS: In vitro TTFields studies indicated an enhanced reduction in the metabolic activity of patient-derived Glioma INvasive marginal (GIN 28) and Glioma contrast enhanced core (GCE 28) GBM As per our journal style, article titles should not include capitalised letters unless these are proper nouns/acronyms. We have therefore used the article title "Electric field responsive nanotransducers for glioblastoma" as opposed to "Electric Field Responsive Nanotransducers for Glioblastoma" as given in the submission system. Please check if this is correct.cells in groups treated with NPs vs. control groups, irrespective of NPs dielectric properties. Our results indicate the inorganic NPs used in this work enhance the intracellular EF effects that could be due to the virtue of bipolar dielectrophoretic and electrophoretic effects. CONCLUSIONS: This work presents preliminary evidence which could help to improve future EF applications for bioelectronic medicine. Furthermore, the merits of spherical morphology, excellent colloidal stability, and low toxicity, make these NPs ideal for future studies for elucidating the detailed mechanism and efficacy upon their delivery in GBM preclinical models.

Metallocatanionic vesicle-mediated enhanced singlet oxygen generation and photodynamic therapy of cancer cells.

In clinics, photodynamic therapy (PDT) is established as a non-invasive therapeutic modality for certain types of cancers and skin disease. However, due to poor water solubility, photobleaching, and the dark toxicity of photosensitizers (PSs), further developments are required to improve the efficiency of PDT. Herein, we report the role of metallocatanionic vesicles (MCVs) in enhancing the phototoxicity of methylene blue (MB) against cancer cells. These MCVs were prepared via a facile and quick solution-solution mixing method using a cationic single-chain metallosurfactant (FeCPC I) in combination with anionic sodium oleate (Na Ol). For singlet oxygen (1O2) generation and PDT studies, two fractions of FeCPC I : Na Ol, i.e., 30 : 70 (V37) and 70 : 30 (V73), were chosen based on their long-term stability in aqueous media. A cationic PS MB was loaded into these vesicles. The MB-loaded MCV 30 : 70 and 70 : 30 fractions enhanced the 1O2 generation by 0.10- and 0.40-fold, respectively, compared with MB alone. Upon illumination using a 650 nm laser, these MB-loaded V73 and V37 MCVs significantly decreased the metabolic activity of MCF-7 cells by ≤50% at a concentration of 0.75 µM. Furthermore, the SOSG assay revealed that the synthesized MCVs enhanced the intracellular 1O2 compared with MB alone. The MB-loaded V73 MCVs showed the highest 1O2-mediated membrane damage and cell-killing effect, as confirmed using the differential nuclear staining assay (DNS), which is attributed to the cellular uptake profile of the different MCV fractions. Altogether, this work shows the advantage of using these biocompatible and dual-charge MCVs as promising delivery vehicles that can enhance the 1O2 generation from the PS. This work suggests the future application of these Fe-MCVs in magnetically guided PDT.

Impedimetric Characterization of Bipolar Nanoelectrodes with Cancer Cells.

Merging of electronics with biology, defined as bioelectronics, at the nanoscale holds considerable promise for sensing and modulating cellular behavior. Advancing our understanding of nanobioelectronics will facilitate development and enable applications in biosensing, tissue engineering, and bioelectronic medicine. However, studies investigating the electrical effects when merging wireless conductive nanoelectrodes with biology are lacking. Consequently, a tool is required to develop a greater understanding of merging conductive nanoparticles with cells. Herein, this challenge is addressed by developing an impedimetric method to evaluate bipolar electrode (BPE) systems that could report on electrical input. A theoretical framework is provided, using impedance to determine if conductive nanoparticles can be polarized and used to drive current. It is then demonstrated that 125 nm of gold nanoparticle (AuNP) bipolar electrodes (BPEs) could be sensed in the presence of cells when incorporated intracellularly at 500 µg/mL using water and phosphate-buffered saline (PBS) as electrolytes. These results highlight how nanoscale BPEs act within biological systems. This research will impact the rational design of using BPE systems in cells for both sensing and actuating applications.

Electric Field Induced Biomimetic Transmembrane Electron Transport Using Carbon Nanotube Porins.

Cells modulate their homeostasis through the control of redox reactions via transmembrane electron transport systems. These are largely mediated via oxidoreductase enzymes. Their use in biology has been linked to a host of systems including reprogramming for energy requirements in cancer. Consequently, the ability to modulate membrane redox systems may give rise to opportunities to modulate underlying biology. The current work aims to develop a wireless bipolar electrochemical approach to form on-demand electron transfer across biological membranes. To achieve this goal, it is shown that by using membrane inserted carbon nanotube porins (CNTPs) that can act as bipolar nanoelectrodes, one can control electron flow with externally applied electric fields across membranes. Before this work, bipolar electrochemistry has been thought to require high applied voltages not compatible with biological systems. It is shown that bipolar electrochemical reaction via gold reduction at the nanotubes can be modulated at low cell-friendly voltages, providing an opportunity to use bipolar electrodes to control electron flux across membranes. The authors provide new mechanistic insight into this newly describe phenomena at the nanoscale. The results presented give rise to a new method using CNTPs to modulate cell behavior via wireless control of membrane electron transfer.

Toward nanobioelectronic medicine: Unlocking new applications using nanotechnology.

Bioelectronic medicine aims to interface electronic technology with biological components and design more effective therapeutic and diagnostic tools. Advances in nanotechnology have moved the field forward improving the seamless interaction between biological and electronic components. In the lab many of these nanobioelectronic devices have the potential to improve current treatment approaches, including those for cancer, cardiovascular disorders, and disease underpinned by malfunctions in neuronal electrical communication. While promising, many of these devices and technologies require further development before they can be successfully applied in a clinical setting. Here, we highlight recent work which is close to achieving this goal, including discussion of nanoparticles, carbon nanotubes, and nanowires for medical applications. We also look forward toward the next decade to determine how current developments in nanotechnology could shape the growing field of bioelectronic medicine. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing.

Top-Down Characterization of an Antimicrobial Sanitizer, Leading From Quenchers of Efficacy to Mode of Action.

We developed a top-down strategy to characterize an antimicrobial, oxidizing sanitizer, which has diverse proposed applications including surface-sanitization of fresh foods, and with benefits for water resilience. The strategy involved finding quenchers of antimicrobial activity then antimicrobial mode of action, by identifying key chemical reaction partners starting from complex matrices, narrowing down reactivity to specific organic molecules within cells. The sanitizer electrolyzed-water (EW) retained partial fungicidal activity against the food-spoilage fungus Aspergillus niger at high levels of added soils (30-750 mg mL-1), commonly associated with harvested produce. Soil with high organic load (98 mg g-1) gave stronger EW inactivation. Marked inactivation by a complex organics mix (YEPD medium) was linked to its protein-rich components. Addition of pure proteins or amino acids (≤1 mg mL-1) fully suppressed EW activity. Mechanism was interrogated further with the yeast model, corroborating marked suppression of EW action by the amino acid methionine. Pre-culture with methionine increased resistance to EW, sodium hypochlorite, or chlorine-free ozonated water. Overexpression of methionine sulfoxide reductases (which reduce oxidized methionine) protected against EW. Fluoroprobe-based analyses indicated that methionine and cysteine inactivate free chlorine species in EW. Intracellular methionine oxidation can disturb cellular FeS-clusters and we showed that EW treatment impairs FeS-enzyme activity. The study establishes the value of a top-down approach for multi-level characterization of sanitizer efficacy and action. The results reveal proteins and amino acids as key quenchers of EW activity and, among the amino acids, the importance of methionine oxidation and FeS-cluster damage for antimicrobial mode-of-action.

Iron-Catalysed Radical Polymerisation by Living Bacteria.

The ability to harness cellular redox processes for abiotic synthesis might allow the preparation of engineered hybrid living systems. Towards this goal we describe a new bacteria-mediated iron-catalysed reversible deactivation radical polymerisation (RDRP), with a range of metal-chelating agents and monomers that can be used under ambient conditions with a bacterial redox initiation step to generate polymers. Cupriavidus metallidurans, Escherichia coli, and Clostridium sporogenes species were chosen for their redox enzyme systems and evaluated for their ability to induce polymer formation. Parameters including cell and catalyst concentration, initiator species, and monomer type were investigated. Water-soluble synthetic polymers were produced in the presence of the bacteria with full preservation of cell viability. This method provides a means by which bacterial redox systems can be exploited to generate "unnatural" polymers in the presence of "host" cells, thus setting up the possibility of making natural-synthetic hybrid structures and conjugates.

Mechanistic insight into heterogeneity of trans-plasma membrane electron transport in cancer cell types.

Trans-plasma membrane electron transfer (tMPET) is a process by which reducing equivalents, either electrons or reductants like ascorbic acid, are exported to the extracellular environment by the cell. TPMET is involved in a number of physiological process and has been hypothesised to play a role in the redox regulation of cancer metabolism. Here, we use a new electrochemical assay to elucidate the 'preference' of cancer cells for different trans tPMET systems. This aids in proving a biochemical framework for the understanding of tPMET role, and for the development of novel tPMET-targeting therapeutics. We have delineated the mechanism of tPMET in 3 lung cancer cell models to show that the external electron transfer is orchestrated by ascorbate mediated shuttling via tPMET. In addition, the cells employ a different, non-shuttling-based mechanism based on direct electron transfer via Dcytb. Results from our investigations indicate that tPMETs are used differently, depending on the cell type. The data generated indicates that tPMETs may play a fundamental role in facilitation of energy reprogramming in malignant cells, whereby tPMETs are utilised to supply the necessary energy requirement when mitochondrial stress occurs. Our findings instruct a deeper understanding of tPMET systems, and show how different cancer cells may preferentially use distinguishable tPMET systems for cellular electron transfer processes.

Mammalian-Cell-Driven Polymerisation of Pyrrole.

A model cancer cell line was used to initiate polymerisation of pyrrole to form the conducting material polypyrrole. The polymerisation was shown to occur through the action of cytosolic exudates rather than that of the membrane redox sites that normally control the oxidation state of iron as ferricyanide or ferrocyanide. The data demonstrate for the first time that mammalian cells can be used to initiate synthesis of conducting polymers and suggest a possible route to detection of cell damage and/or transcellular processes through in situ and amplifiable signal generation.

New Perspectives on Iron Uptake in Eukaryotes.

All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the "macroscopic" transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions.

Electrochemical System for the Study of Trans-Plasma Membrane Electron Transport in Whole Eukaryotic Cells.

The study of trans-plasma membrane electron transport (tPMET) in oncogenic systems is paramount to the further understanding of cancer biology. The current literature provides methodology to study these systems that hinges upon mitochondrial knockout genotypes in conjunction with cell surface oxygen consumption, or the detection of an electron acceptor using colorimetric methods. However, when using an iron redox based system to probe tPMET, there is yet to be a method that allows for the simultaneous quantification of iron redox states while providing an exceptional level of sensitivity. Developing a method to simultaneously analyze the redox state of a reporter molecule would give advantages in probing the underlying biology. Herein, we present an electrochemical based method that allows for the quantification of both ferricyanide and ferrocyanide redox states to a highly sensitive degree. We have applied this system to a novel application of assessing oncogenic cell-driven iron reduction and have shown that it can effectively quantitate and identify differences in iron reduction capability of three lung epithelial cell lines.

Fast, Ultrasensitive Detection of Reactive Oxygen Species Using a Carbon Nanotube Based-Electrocatalytic Intracellular Sensor.

Herein, we report a highly sensitive electrocatalytic sensor-cell construct that can electrochemically communicate with the internal environment of immune cells (e.g., macrophages) via the selective monitoring of a particular reactive oxygen species (ROS), hydrogen peroxide. The sensor, which is based on vertically aligned single-walled carbon nanotubes functionalized with an osmium electrocatalyst, enabled the unprecedented detection of a local intracellular "pulse" of ROS on a short second time scale in response to bacterial endotoxin (lipopolysaccharide-LPS) stimulation. Our studies have shown that this initial pulse of ROS is dependent on NADPH oxidase (NOX) and toll like receptor 4 (TLR4). The results suggest that bacteria can induce a rapid intracellular pulse of ROS in macrophages that initiates the classical innate immune response of these cells to infection.

Electrically-driven modulation of surface-grafted RGD peptides for manipulation of cell adhesion.

Reported herein is a switchable surface that relies on electrically-induced conformational changes within surface-grafted arginine-glycine-aspartate (RGD) oligopeptides as the means of modulating cell adhesion.

Electrochemical detection of oestrogen binding protein interaction with oestrogen in Candida albicans cell lysate.

Previously we reported an electrochemical method to quantitatively detect vertebrate oestrogens using wild type Saccharomyces cerevisiae cells. That assay required the use of a double mediator system, a five-hour incubation period and had a maximum detection limit of around 11 nM 17ß-oestradiol. In the work reported here we have sought to systematically increase the utility and decrease the complexity of the whole cell assay. The steps we took to achieve this goal were in order; lysing the cells to remove transport constraints, removing the lipophilic mediator and conducting the assay with the hydrophilic mediator only and finally performing the assay in a complex medium to demonstrate its specificity. Linear sweep voltammetry was used to investigate the interaction of mediators with NADH. The assay is now cell free and functions in a complex substrate. The linear response range upper limit has been raised to 100 nM with a calculated limit of detection of 0.005 nM with a limit of determination of 0.014 nM and the assay period has been reduced to 20 min.