The cellular zeta potential: cell electrophysiology beyond the membrane

H2S Donor Functionalized Molecular Machine for Combating Multidrug-Resistant Bacteria Infected Chronic Wounds

Chronic wounds are a worldwide medical challenge due to the complex and multifaceted etiologies, including bacterial infection, persistent inflammation, and impaired angiogenesis. Developing a comprehensive strategy integrating antibiosis and anti-inflammation to promote revascularization and accelerate wound healing is highly desirable. Nevertheless, current therapeutic methods still face two major challenges: 1) how to combat bacterial drug resistance, 2) how to achieve spatiotemporal control over bacterial elimination and inflammation reduction. To address these issues, a novel H2S donor functionalized molecular machine (MM), ACR-DM-HS, was developed. It selectively binds to and disturbs the bacterial membrane through a light-active vibronic-driven mechanochemical action (VDA), which synergizes with photodynamic therapy (PDT) to efficiently eradicate multidrug-resistant bacteria and biofilms, and conquers the evolution of bacterial resistance. Furthermore, it releases H2S in infected tissues to scavenge excess reactive oxygen species (ROS), inhibit the secretion of inflammatory factors, promote angiogenesis, and accelerate the healing of diabetic wounds in vivo. This work provides an integrated strategy combining antibiotics and anti-inflammation to treat with multidrug resistance bacterial-infected chronic wounds.

Selectivity of membrane-active peptides: the role of electrostatics and other membrane biophysical properties

Membrane-active peptides (MAPs) are versatile molecules that interact with lipid bilayers, facilitating processes such as antimicrobial defense, anticancer activity, and membrane translocation. Given that most MAPs are cationic, their selectivity for specific cell membranes has traditionally been attributed to variations in membrane surface charge. However, growing evidence suggests that electrostatics alone cannot fully explain MAPs selectivity. Instead, MAPs activity is also strongly influenced by other membrane biophysical properties, such as lipid packing, phase state, curvature, and the spatial distribution of hydrophobic and charged residues within the peptide sequence. In this review, we summarize the current knowledge on the biophysical determinants of MAPs selectivity. We begin by examining membrane and cell surface electrostatics and their influence on MAPs-membrane interactions, including electrostatically driven peptide conformational changes and lipid recruitment. We then broaden the discussion to include non-electrostatic factors, such as membrane curvature and rheology, which are primarily influenced by sterol or hopanoid content, as well as acyl chain unsaturation and branching. Together, these processes highlight that MAPs selectivity is not governed by any single membrane property but instead emerges from a synergistic interplay of electrostatic, hydrophobic, and topological factors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12551-025-01309-7.

Antibacterial Polymers Based on Two Orthogonal Binding Motifs Coalesce with Bacterial Matter

Addressing the growing concern about antibiotic-resistant bacteria, we have developed a series of polymers exhibiting intrinsic antibacterial activities with a dual-targeting system that induces physical lysis upon copolymer coalescence with bacterial matter. These polymers are equipped with two orthogonal binding motifs that form electrostatic interactions and dynamic covalent complexes on bacterial surfaces and exhibit potent antibacterial activity against Gram-positive and Gram-negative bacteria. The effect of the chemical composition and architecture of copolymers incorporating phenylboronic acid and quaternary ammonium groups on the antimicrobial activities was systematically examined. This work expands the current chemical repertoire to combat antimicrobial resistance by intrinsically antibacterial polymers with a unique mode of action.

Meeting Review: "National Cancer Institute Conference on Cancer Bioelectricity" September 12, 2024

The Office of Cancer Complementary and Alternative Medicine, part of the Division of Cancer Treatment and Diagnosis under the National Cancer Institute (NCI), supports research in diverse areas of cancer therapeutics such as microbial therapies, herbal remedies, and mind-body practices. Recently they have become especially interested in the emerging role of bioelectricity in cancer biology and organized a virtual meeting with some of the top scientists in the field. In this report, we overview this first-of-its-kind Naional Institute of Health (NIH)-sponsored meeting, which featured talks from 14 researchers exploring the role of bioelectricity in cancer biology. The talks covered a wide range of topics, including excellent background information on how cell collectives change their bioelectrical coupling and set points during cancer formation, new tools for reading and writing bioelectrical signatures in cells and whole organisms, how ion channels that are involved in setting those signatures affect canonical pathways in development and tumor growth, and the methods for modeling bioelectrical interactions and information transfer in cell collectives. Especially exciting were the translational technologies that were highlighted, including new diagnostics, metastasis inhibition therapies, and more efficient detection of surgical margins. The meeting concluded with funding opportunities available from the NCI Division of Cancer Biology, Innovative Molecular Analysis Technologies Program, and the Small Business Innovation Research Development Center.

Evaluating refrigeration and antibiotic treatment for maintaining urine electrophysiology

BACKGROUND

Electrophysiological analysis of urine has shown utility in differentiating between healthy and bladder cancer specimens, offering a rapid, label-free alternative to molecular methods. However, transporting and preserving urine samples from collection to the laboratory poses logistical challenges that could impact the reliability of electrophysiological measurements.

OBJECTIVE

This study investigates the effects of prolonged refrigeration on the dielectric properties and ζ-potential of urine specimens and evaluate whether antibiotic treatment can enhance sample preservation without altering electrophysiological properties. A new methodology to evaluate urine specimen quality and determine bacterial contamination, using electrophysiological modalities, is presented.

METHODS

Mid-stream urine samples from healthy participants (n =  4) were collected and divided into untreated and 1% penicillin/streptomycin-treated groups. Samples were analysed at baseline prior to storage at 4°C, with further analysis every 24 hours for 96 hours. Changes in dielectrophoresis (DEP) response and ζ-potential were measured using a 3DEP cytometer (Deparator, UK) and Malvern Panalytical Zetasizer Nano ZS90 (Malvern, UK), respectively. Chemical analyses, including pH and nitrite levels, and microscopic examinations were also conducted.

RESULTS & LIMITATIONS

Significant electrophysiological changes were observed in both untreated and antibiotic-treated urine samples over time. Both groups showed a linear increase of change in DEP response and ζ-potential values, from baseline over time. Untreated samples exhibited significant deviations in DEP and ζ-potential from baseline after 48 hours, with significance at 72 hours (P < 0.05). Treated samples only showed significant changes in ζ-potential at 96 hours (P < 0.05). Chemical analysis indicated increased pH and nitrite presence in untreated samples at 48 hours, indicating bacterial growth. Treated samples took more than 48 hours to show changes in both chemical parameters. Limitations include the relatively small study sample size, not evaluating the preservatory effects of UTI-specific antibiotics, such as nitrofurantoin and trimethoprim, and exploring different drug concentrations.

CONCLUSION

Prolonged refrigeration can maintain the quality of urine samples for up to 48 hours with antibiotic treatment. Current UK and European guidelines recommend urinalysis within 24 hours of specimen collection; the findings of this study support the use of DEP and ζ-potential analysis as practical clinical tests in a mail-in screening setting, provided appropriate sample preservation measures are taken.

Transition metal complexes: next-generation photosensitizers for combating Gram-positive bacteria

The rise of antibiotic-resistant Gram-positive bacterial infections poses a significant threat to public health, necessitating the exploration of alternative therapeutic strategies. A photosensitizer (PS) can convert energy from absorbed photon into reactive oxygen species (ROS) for damaging bacteria. This photoinactivation action bypassing conventional antibiotic mechanism is less prone to resistance development, making antibacterial photodynamic therapy (aPDT) highly efficient in combating Gram-positive bacteria. Photodynamic transition metal complexes leveraging the unique properties of metals to enhance the aPDT activity are the next-generation PS. This review provides an overview of metal-based PS for combating Gram-positive bacteria. Based on the structures, these metal-PS could be mainly classified as metal-tetrapyrrole derivatives, ruthenium complexes, iridium complexes, and zinc complexes. PS based on complexes of other transition metals such as silver, cobalt, and rhenium are also presented. Finally, we summarize the advantages and shortcomings of these metal- PS, conclude some critical aspects impacting their aPDT performances and give a perspective on their future development.

Ion channels in macrophages: Implications for disease progression

RATIONALE

Macrophages are immune cells found throughout the body and exhibit morphological and functional diversity. Macrophages have been implicated in a wide range of diseases, including autoimmune diseases, acute liver injury, cardiovascular diseases, lung diseases and tumours. Ion channels are transmembrane glycoproteins with important functions in maintaining homeostasis in the intra- and extracellular environment and mediating signal transduction. Many studies have shown that different types of ion channels influence the role of macrophages in the development of various diseases. In recent years, studies on the role of ion channels in macrophages in immune regulation and inflammatory responses have attracted much attention.

OBJECTIVE AND FINDINGS

In order to gain a deeper understanding of the role of macrophage ion channels, this paper reviews the recent research progress on the role of macrophage ion channels in recent years. The aim is to explore the role of different ion channels in the regulation of macrophage function and their impact on a variety of disease processes. The most studied channels are calcium, sodium and potassium channels, most of which are located in the cell membrane. Among these, TRP channels have a more complex role in M1 and M2 macrophage types.

CONCLUSION

Ion channels are critical for the functional regulation of macrophages. Targeting ion channels provides new avenues for disease prevention and treatment. This review provides researchers with new ideas and introduces readers to the current state of research on ion channels in macrophages.

Role of DHA in a Physicochemical Study of a Model Membrane of Grey Matter

The present study investigates a multicomponent lipid system that simulates the neuronal grey matter membrane, employing molecular acoustics as a precise, straightforward, and cost-effective methodology. Given the significance of omega-3 polyunsaturated fatty acids in the functionality of cellular membranes, this research examines the effects of reducing 1-palmitoyl-2-docosahexaenoylphosphatylcholine (PDPC) content on the compressibility and elasticity of the proposed membrane under physiological conditions. Our results align with bibliographic data obtained through other techniques, showing that as the proportion of PDPC increases in the grey matter membrane model, the system's compressibility decreases, and the membrane's elasticity increases, as evidenced by the reduction in the bulk modulus. These results could be interpreted in light of the emerging model of lipid rafts, in which esterified DHA infiltrates and remodels their architecture. We contend that the results obtained may serve as a bridge between biophysics and cellular biology.

Translational insights into the hormetic potential of carbon dioxide: from physiological mechanisms to innovative adjunct therapeutic potential for cancer

Background

Carbon dioxide (CO2), traditionally viewed as a mere byproduct of cellular respiration, plays a multifaceted role in human physiology beyond simple elimination through respiration. CO2 may regulate the tumor microenvironment by significantly affecting the release of oxygen (O2) to tissues through the Bohr effect and by modulating blood pH and vasodilation. Previous studies suggest hypercapnia (elevated CO2 levels) might trigger optimized cellular mechanisms with potential therapeutic benefits. The role of CO2 in cellular stress conditions within tumor environments and its impact on O2 utilization offers a new investigative area in oncology.

Objectives

This study aims to explore CO2's role in the tumor environment, particularly how its physiological properties and adaptive responses can influence therapeutic strategies.

Methods

By applying a structured translational approach using the Work Breakdown Structure method, the study divided the analysis into six interconnected work packages to comprehensively analyze the interactions between carbon dioxide and the tumor microenvironment. Methods included systematic literature reviews, data analyses, data integration for identifying critical success factors and exploring extracellular environment modulation. The research used SMART criteria for assessing innovation and the applicability of results.

Results

The research revealed that the human body's adaptability to hypercapnic conditions could potentially inform innovative strategies for manipulating the tumor microenvironment. This could enhance O2 utilization efficiency and manage adaptive responses to cellular stress. The study proposed that carbon dioxide's hormetic potential could induce beneficial responses in the tumor microenvironment, prompting clinical protocols for experimental validation. The research underscored the importance of pH regulation, emphasizing CO2 and carbonic acid's role in modulating metabolic and signaling pathways related to cancer.

Conclusion

The study underscores CO2 as vital to our physiology and suggests potential therapeutic uses within the tumor microenvironment. pH modulation and cellular oxygenation optimization via CO2 manipulation could offer innovative strategies to enhance existing cancer therapies. These findings encourage further exploration of CO2's therapeutic potential. Future research should focus on experimental validation and exploration of clinical applications, emphasizing the need for interdisciplinary and collaborative approaches to tackle current challenges in cancer treatment.

Rapid Surface Charge Mapping Based on a Liquid Crystal Microchip

Rapid surface charge mapping of a solid surface remains a challenge. In this study, we present a novel microchip based on liquid crystals for assessing the surface charge distribution of a planar or soft surface. This chip enables rapid measurements of the local surface charge distribution of a charged surface. The chip consists of a micropillar array fabricated on a transparent indium tin oxide substrate, while the liquid crystal is used to fill in the gaps between the micropillar structures. When an object is placed on top of the chip, the local surface charge (or zeta potential) influences the orientation of the liquid crystal molecules, resulting in changes in the magnitude of transmitted light. By measuring the intensity of the transmitted light, the distribution of the surface charge can be accurately quantified. We calibrated the chip in a three-electrode configuration and demonstrated the validity of the chip for rapid surface charge mapping using a borosilicate glass slide. This chip offers noninvasive, rapid mapping of surface charges on charged surfaces, with no need for physical or chemical modifications, and has broad potential applications in biomedical research and advanced material design.