Intracellular ROS mediates gas plasma-facilitated cellular transfection in 2D and 3D cultures

Site-selected in situ polymerization for living cell surface engineering

The construction of polymer-based mimicry on cell surface to manipulate cell behaviors and functions offers promising prospects in the field of biotechnology and cell therapy. However, precise control of polymer grafting sites is essential to successful implementation of biomimicry and functional modulation, which has been overlooked by most current research. Herein, we report a biological site-selected, in situ controlled radical polymerization platform for living cell surface engineering. The method utilizes metabolic labeling techniques to confine the growth sites of polymers and designs a Fenton-RAFT polymerization technique with cytocompatibility. Polymers grown at different sites (glycans, proteins, lipids) have different membrane retention time and exhibit differential effects on the recognition behaviors of cellular glycans. Of particular importance is the achievement of in situ copolymerization of glycomonomers on the outermost natural glycan sites of cell membrane, building a biomimetic glycocalyx with distinct recognition properties.

Cold atmospheric plasma mediated cell membrane permeation and gene delivery-empirical interventions and pertinence

Delivery of genetic material to cells is an integral tool to analyze and reveal the genetic interventions in normal cellular processes and differentiation, disease development and for gene therapy. It has profound applications in pharmaceutical, agricultural, environmental and biotechnological sectors. The major methods relied for gene delivery or transfection requires either viral vectors or xenogenic carrier molecules, which renders probabilistic carcinogenic, immunogenic and toxic effects. A newly evolved physical method, Cold atmospheric plasma induced transfection neither needs vector nor carriers. The 4th state of matter 'Plasma' is a quasineutral ionized gas-containing ions, neutral atoms, electrons and reactive radical molecules; and possess electric and magnetic field, along with emanating photons and UV radiations. Plasma produced at atmospheric pressure conditions, and having room temperature is conferred as Low temperature plasma or Cold atmospheric plasma. Selective and controlled application of cold atmospheric plasma on tissues creates temporary, restorable pores on cell membranes that could be diligently manipulated for gene delivery. Research in this regard attained pace since 2016. Cold atmospheric plasma induces transfection by lipid peroxidation, electroporation, and clathrin dependent endocytosis in cell membranes, by virtue of its reactive radicals and electric field. Plasma formed reactive radicals, especially 'OH' penetrates to the cell membrane and cleaves the phosphate head group of membrane lipids, peroxidize and detaches fatty acid tails. This decreases membrane thickness, increases membrane fluidity and permeability. Simultaneously plasma formed ions, electrons and reactive radicals accumulate over cells, generating local electric field and neutralize the negative charge of cell membrane. This induces stress on cell membrane and disrupts its structural integrity, by infringing the dynamic equilibrium between surface tension, spatial repulsion and linear tension between the head groups of phospholipids, generating minute pores. Neutralization of membrane charge promote foreign, external plasmid and gene movement towards cells and its enhanced binding with ligands and receptors on cell membrane, instigating clathrin dependent endocytosis. In vitro and in vivo studies have successfully delivered plasmids, linear DNA, siRNA and miRNA to several established cell lines like, HeLa, PC12, CHL, HUVEC, Jurkat, MCF, SH-SY5Y, HT, B16F10, HaCaT, LP-1, etc., and live C57BL/6 and BALB/c mice, using cold atmospheric plasma. This review delineates the cell surface mechanism of plasma-induced transfection, critically summarizes the research progress in this context, plasma devices used, and the inimitable features of this method. Metabolic activity, cell function, and viability are not adversely affected by this process; moreover, the cell permeating plasma-formed reactive radicals are effectively defended by cellular antioxidant mechanisms like superoxide dismutase, glutathione reductase and cytokines, alleviating its toxicity. A deeper understanding on mechanism of plasma action on cells, its aftermath, and the research status in this field would provide a better insight on future avenues of research.

Synthesis, Biophysical Properties, and Antitumor Activity of Antisense Oligonucleotides Conjugated with Anisamide

Antisense oligonucleotides (ASONs) have proven potential for the treatment of various diseases. However, their limited bioavailability restricts their clinical application. New structures with improved enzyme resistance stability and efficient drug delivery are needed. In this work, we propose a novel category of ASONs bearing anisamide conjugation at phosphorothioate sites for oncotherapy. ASONs can be conjugated with the ligand anisamide very efficiently and flexibly in a solution. The conjugation sites and the ligand amount both influence anti-enzymatic stability and cellular uptake, resulting in changes in antitumor activity that are detectable by cytotoxicity assay. The conjugate with double anisamide (T6) was identified as the optimal conjugate, and its antitumor activity and the underlying mechanism were examined further in vitro and in vivo. This paper presents a new strategy for the design of nucleic acid-based therapeutics with improved drug delivery and biophysical and biological efficacy.

Plasma Promotes Fungal Cellulase Production by Regulating the Levels of Intracellular NO and Ca2

For the industrial-scale production of useful enzymes by microorganisms, technological development is required for overcoming a technical bottleneck represented by poor efficiency in the induction of enzyme gene expression and secretion. In this study, we evaluated the potential of a non-thermal atmospheric pressure plasma jet to improve the production efficiency of cellulolytic enzymes in Neurospora crassa, a filamentous fungus. The total activity of cellulolytic enzymes and protein concentration were significantly increased (1.1~1.2 times) in media containing Avicel 24–72 h after 2 and 5 min of plasma treatment. The mRNA levels of four cellulolytic enzymes in fungal hyphae grown in media with Avicel were significantly increased (1.3~17 times) 2–4 h after a 5 min of plasma treatment. The levels of intracellular NO and Ca²⁺ were increased in plasma-treated fungal hyphae grown in Avicel media after 48 h, and the removal of intracellular NO decreased the activity of cellulolytic enzymes in media and the level of vesicles in fungal hyphae. Our data suggest that plasma treatment can promote the transcription and secretion of cellulolytic enzymes into the culture media in the presence of Avicel (induction condition) by enhancing the intracellular level of NO and Ca²⁺.

Aberrant Expressional Profiling of Small RNA by Cold Atmospheric Plasma Treatment in Human Chronic Myeloid Leukemia Cells

Small RNAs (sRNAs), particularly microRNAs (miRNAs), are functional molecules that modulate mRNA transcripts and have been implicated in the etiology of various types of cancer. Cold atmospheric plasma (CAP) is a physical technology widely used in the field of cancer treatment after exhibiting extensive lethality on cancer cells. However, few studies have reported the exact role of miRNAs in CAP-induced anti-cancer effects. The aim of the present study was to determine whether miRNAs are involved in CAP-induced cytotoxicity by using high-throughput sequencing. Our research demonstrated that 28 miRNAs were significantly changed (17 upregulated and 11downregulated) following 24 h of treatment with a room-temperature argon plasma jet for 90 s compared with that of the untreated group in human chronic myeloid leukemia K562 cells. GO enrichment analysis revealed that these target genes were related to cell organelles, protein binding, and single-organism processes. Furthermore, KEGG pathway analysis demonstrated that the target genes of differentially expressed miRNAs were primarily involved in the cAMP signaling pathway, AMPK signaling pathway, and phosphatidylinositol signaling system. Taken together, our study demonstrated that CAP treatment could significantly alter the small RNA expression profile of chronic myeloid leukemia cells and provide a novel theoretical insight for elucidating the molecular mechanisms in CAP biomedicine application.

Carrier-Free Cellular Transport of CRISPR/Cas9 Ribonucleoprotein for Genome Editing by Cold Atmospheric Plasma

Simple Summary

CRISPR/Cas9 system as a potential gene editing platform has been widely applied in biological engineering and disease therapies. To achieve precise gene targeting, active CRISPR/Cas9 components must be efficiently transported to targeted cells. As a simple and effective strategy, Cold Atmospheric Plasma (CAP) treatment has been demonstrated for the transmembrane delivery of various exogenous materials. In comparison with carrier-dependent delivery methods, this carrier-free platform provides a promising alternative to circumvent the obstacles of biosafety and complicated preparation processes. In this work, a CAP-based CRISPR/Cas9 carrier-free delivery platform has been established and corresponding mechanism related to efficient transportation has been explored. Briefly, the efficient production of bioactive species in culture media after CAP treatment alters cell membrane potential and permeability, which facilitates cytosolic delivery of active CRISPR/Cas9 components via passive diffusion and ATP-dependent endocytosis pathways, resulting in efficient genome editing and gene silencing. This carrier-free strategy using CAP-based transportation may also be extended to other active biomolecules in drug delivery and gene therapy.

Abstract

A carrier-free CRISPR/Cas9 ribonucleoprotein delivery strategy for genome editing mediated by a cold atmospheric plasma (CAP) is described. The CAP is promising in many biomedical applications due to efficient production of bioactive ionized species. The MCF-7 cancer cells after CAP exposure exhibit increased extracellular reactive oxygen and nitrogen species (RONS) and altered membrane potential and permeability. Hence, transmembrane transport of Ca²⁺ into the cells increases and accelerates ATP hydrolysis, resulting in enhanced ATP-dependent endocytosis. Afterwards, the increased Ca²⁺ and ATP contents promote the release of cargo into cytoplasm due to the enhanced endosomal escape. The increased membrane permeability also facilitates passive diffusion of foreign species across the membrane into the cytosol. After CAP exposure, the MCF-7 cells incubated with Cas9 ribonucleoprotein (Cas9-sgRNA complex, Cas9sg) with a size of about 15 nm show 88.9% uptake efficiency and 65.9% nuclear import efficiency via passive diffusion and ATP-dependent endocytosis pathways. The efficient transportation of active Cas9sg after the CAP treatment leads to 21.7% and 30.2% indel efficiencies in HEK293T and MCF-7 cells, respectively. This CAP-mediated transportation process provides a simple and robust alternative for the delivery of active CRISPR/Cas9 ribonucleoprotein. Additionally, the technique can be extended to other macro-biomolecules and nanomaterials to cater to different biomedical applications.

Impact of Reactive Oxygen and Nitrogen Species Produced by Plasma on Mdm2-p53 Complex

The study of protein–protein interactions is of great interest. Several early studies focused on the murine double minute 2 (Mdm2)–tumor suppressor protein p53 interactions. However, the effect of plasma treatment on Mdm2 and p53 is still absent from the literature. This study investigated the structural changes in Mdm2, p53, and the Mdm2–p53 complex before and after possible plasma oxidation through molecular dynamic (MD) simulations. MD calculation revealed that the oxidized Mdm2 bounded or unbounded showed high flexibility that might increase the availability of tumor suppressor protein p53 in plasma-treated cells. This study provides insight into Mdm2 and p53 for a better understanding of plasma oncology.

Cold Atmospheric Plasma Promotes the Immunoreactivity of Granulocytes In Vitro

Cold atmospheric plasma (CAP) reduces bacteria and interacts with tissues and cells, thus improving wound healing. The CAP-related induction of neutrophils was recently described in stained sections of wound tissue in mice. Consequently, this study aimed to examine the functionality of human polymorphonuclear cells (PMN)/granulocytes through either a plasma-treated solution (PTS) or the direct CAP treatment with different plasma modes and treatment durations. PTS analysis yielded mode-dependent differences in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) after CAP treatment. Live-cell imaging did not show any chemo-attractive or NETosis-inducing effect on PMNs treated with PTS. The time to maximum ROS production (TmaxROS) in PMNs was reduced by PTS and direct CAP treatment. PMNs directly treated with CAP showed an altered cell migration dependent on the treatment duration as well as decreased TmaxROS without inducing apoptosis. Additionally, flow cytometry showed enhanced integrin and selectin expression, as a marker of activation, on PMN surfaces. In conclusion, the modification of PMN immunoreactivity may be a main supporting mechanism for CAP-induced improvement in wound healing.

Cold Atmospheric Plasma Promotes Killing of Staphylococcus aureus by Macrophages

Macrophages are important immune cells that are involved in the elimination of microbial pathogens. Following host invasion, macrophages are recruited to the site of infection, where they launch antimicrobial defense mechanisms. Effective microbial clearance by macrophages depends on phagocytosis and phagolysosomal killing mediated by oxidative burst, acidification, and degradative enzymes. However, some pathogenic microorganisms, including some drug-resistant bacteria, have evolved sophisticated mechanisms to prevent phagocytosis or escape intracellular degradation. Cold atmospheric plasma (CAP) is an emerging technology with promising bactericidal effects. Here, we investigated the effect of CAP on Staphylococcus aureus phagocytosis by RAW 264.7 macrophage-like cells. We demonstrate that CAP treatment increases intracellular concentrations of reactive oxygen species (ROS) and nitric oxide and promotes the elimination of both antibiotic-sensitive and antibiotic-resistant S. aureus by RAW 264.7 cells. This effect was inhibited by antioxidants indicating that the bactericidal effect of CAP was mediated by oxidative killing of intracellular bacteria. Furthermore, we show that CAP promotes the association of S. aureus to lysosomal-associated membrane protein 1 (LAMP-1)-positive phagosomes, in which bacteria are exposed to low pH and cathepsin D hydrolase. Taken together, our results provide the first evidence that CAP activates defense mechanisms of macrophages, ultimately leading to bacterial elimination. IMPORTANCE Staphylococcus aureus is the most frequent cause of skin and soft tissue infections. Treatment failures are increasingly common due to antibiotic resistance and the emergence of resistant strains. Macrophages participate in the first line of immune defense and are critical for coordinated defense against pathogenic bacteria. However, S. aureus has evolved sophisticated mechanisms to escape macrophage killing. In the quest to identify novel antimicrobial therapeutic approaches, we investigated the activity of cold atmospheric plasma (CAP) on macrophages infected with S. aureus. Here, we show that CAP treatment promotes macrophage ability to eliminate internalized bacteria. Importantly, CAP could trigger killing of both antibiotic-sensitive and antibiotic-resistant strains of S. aureus. While CAP did not affect the internalization capacity of macrophages, it increased oxidative-dependent bactericidal activity and promoted the formation of degradative phagosomes. Our study shows that CAP has beneficial effects on macrophage defense mechanisms and may potentially be useful in adjuvant antimicrobial therapies.

Delivery and expression of plasmid DNA into cells by a novel non-thermal plasma source

Medical applications such as plasma assisted gene transfer is a minimally invasive approach that can substantially reduce potential discomfort of treated area. Atmospheric pressure plasma discharge is an effective approach to deliver plasmid DNA for in vitro and in vivo applications. We investigated plasma assisted delivery in vitro in mouse melanoma cells (B16F10) using a novel surface plasma device, which is operated in air. We evaluated the influence of applied voltage and distance between the surface device and cell monolayer. We found no significant effect on the viability of cells. Highest expression following delivery of a plasmid encoding green fluorescent protein was achieved with an applied voltage of 11.25 kV at a 2 mm distance and 5 s exposure time. To better understand the influence of oxidative damages and stress on cells after plasma delivery, a mRNA expression study was performed. Our results indicated that TNFα mRNA was significantly upregulated. The mRNA response may be attributed to the RONS generated by plasma; however, this mRNA upregulation was not adequate to be reflected in a coordinate protein upregulation. From the results reported here, it is clear that this novel plasma device could be used for plasmid delivery.

Plasma enhance drug sensitivity to bortezomib by inhibition of cyp1a1 in myeloma cells

Background

Drug resistance is one of the major problems encountered in clinical therapy of multiple myeloma treatment. Combination treatment with several drugs may increase the sensitivity and overcome drug resistance.

Methods

Here, we combined chemotherapy with a newly developed technology, cold atmospheric plasma, to enhance drug sensitivity.

Results

We found that plasma treatment had a synergistic anti-cancer effect with a first line drug (bortezomib). Based on our previous study, we further found that plasma treatment could inhibit Notch pathway and down-regulate cyp1a1 expression and enzyme activity, which contributing to the enhanced drug sensitivity to bortezomib after combination of bortezomib with gas plasma.

Conclusions

Our results showed a new strategy to overcome drug resistance by combination of traditional chemotherapy with cold atmospheric plasma.

Direct transfection of clonal organoids in Matrigel microbeads: a promising approach toward organoid-based genetic screens

Organoid cultures in 3D matrices are relevant models to mimic the complex in vivo environment that supports cell physiological and pathological behaviors. For instance, 3D epithelial organoids recapitulate numerous features of glandular tissues including the development of fully differentiated acini that maintain apico-basal polarity with hollow lumen. Effective genetic engineering in organoids would bring new insights in organogenesis and carcinogenesis. However, direct 3D transfection on already formed organoids remains challenging. One limitation is that organoids are embedded in extracellular matrix and grow into compact structures that hinder transfection using traditional techniques. To address this issue, we developed an innovative approach for transgene expression in 3D organoids by combining single-cell encapsulation in Matrigel microbeads using a microfluidic device and electroporation. We demonstrate that direct electroporation of encapsulated organoids reaches up to 80% of transfection efficiency. Using this technique and a morphological read-out that recapitulate the different stages of tumor development, we further validate the role of p63 and PTEN as key genes in acinar development in breast and prostate tissues. We believe that the combination of controlled organoid generation and efficient 3D transfection developed here opens new perspectives for flow-based high-throughput genetic screening and functional genomic applications.

Alteration of metabolite profiling by cold atmospheric plasma treatment in human myeloma cells

Background

Despite new progress of chemotherapy in multiple myeloma (MM) clinical treatment, MM is still a refractory disease and new technology is needed to improve the outcomes and prolong the survival. Cold atmospheric plasma is a rapidly developed technology in recent years, which has been widely applied in biomedicine. Although plasma could efficiently inactivate various tumor cells, the effects of plasma on tumor cell metabolism have not been studied yet.

Methods

In this study, we investigated the metabolite profiling of He plasma treatment on myeloma tumor cells by gas-chromatography time-of-flight (GC-TOF) mass-spectrometry. Meanwhile, by bioinformatic analysis such as GO and KEGG analysis we try to figure out the metabolism pathway that was significantly affected by gas plasma treatment.

Results

By GC-TOF mass-spectrometry, 573 signals were detected and evaluated using PCA and OPLS-DA. By KEGG analysis we listed all the differential metabolites and further classified into different metabolic pathways. The results showed that beta-alanine metabolism pathway was the most significant change after He gas plasma treatment in myeloma cells. Besides, propanoate metabolism and linoleic acid metabolism should also be concerned during gas plasma treatment of cancer cells.

Conclusions

Cold atmospheric plasma treatment could significantly alter the metabolite profiling of myeloma tumor cells, among which, the beta-alanine metabolism pathway is the most susceptible to He gas plasma treatment.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0541-z) contains supplementary material, which is available to authorized users.

Basic Research in Plasma Medicine - A Throughput Approach from Liquids to Cells

In plasma medicine, ionized gases with temperatures close to that of vertebrate systems are applied to cells and tissues. Cold plasmas generate reactive species known to redox regulate biological processes in health and disease. Pre-clinical and clinical evidence points to beneficial effects of plasma treatment in the healing of chronic ulcer of the skin. Other emerging topics, such as plasma cancer treatment, are receiving increasing attention. Plasma medical research requires interdisciplinary expertise in physics, chemistry, and biomedicine. One goal of plasma research is to characterize plasma-treated cells in a variety of specific applications. This includes, for example, cell count and viability, cellular oxidation, mitochondrial activity, cytotoxicity and mode of cell death, cell cycle analysis, cell surface marker expression, and cytokine release. This study describes the essential equipment and workflows required for such research in plasma biomedicine. It describes the proper operation of an atmospheric pressure argon plasma jet, specifically monitoring its basic emission spectra and feed gas settings to modulate reactive species output. Using a high-precision xyz-table and computer software, the jet is hovered in millisecond-precision over the cavities of 96-well plates in micrometer-precision for maximal reproducibility. Downstream assays for liquid analysis of redox-active molecules are shown, and target cells are plasma-treated. Specifically, melanoma cells are analyzed in an efficient sequence of different consecutive assays but using the same cells: measurement of metabolic activity, total cell area, and surface marker expression of calreticulin, a molecule important for the immunogenic cell death of cancer cells. These assays retrieve content-rich biological information about plasma effects from a single plate. Altogether, this study describes the essential steps and protocols for plasma medical research.

Cold atmospheric plasma restores tamoxifen sensitivity in resistant MCF-7 breast cancer cell

Cancer recurrence, which is frequently accompanied by chemotherapy, has been a challenge in cancer treatment. This study was carried out to examine the potential applications of the reactive oxygen species (ROS)-producing cold atmospheric plasma (CAP) to overcome the cancer cells' drug resistance, which has been emerging as an alternative therapeutic tool for cancer. For this, we developed a tamoxifen (Tam)-resistant MCF-7 (MCF-7/TamR) breast cancer cell model and examined the effect of CAP on the recovery of Tam sensitivity at the cellular and molecular level. The ROS level was increased 1.9-fold in CAP-treated MCF-7/TamR cells compared to the non-treated cell. CAP was proven to restore sensitivity by up to 50% for MCF-7/TamR cells against Tam after CAP treatment. The comparison of genome-wide expression between the acquisition of Tam resistance and CAP treatment identified 20 genes that commonly showed significant expression changes. Notably, all the genes except two have been oppositely dysregulated in the two cellular statuses, and the majority of them are known to contribute to the acquisition of Tam resistance. The protein expression of selected genes, MX1 and HOXC6, was recovered to that of their parental cell by CAP. Furthermore, the dysregulation of MX1 and HOXC6 in MCF-7/TamR alleviated the drug sensitivity recovery effect of CAP. Taken together, CAP inhibited the growth of Tam-resistant MCF-7 cancer cells and reset it to the Tam-sensitive status by restoring the expression of drug resistance-related genes. These findings may lend credence to CAP as an alternative or complementary tool in the treatment or prevention of Tam-resistant cancer.

Surface chemistry and germination improvement of Quinoa seeds subjected to plasma activation

Plasma treatment is recognized as a suitable technology to improve germination efficiency of numerous seeds. In this work Quinoa seeds have been subjected to air plasma treatments both at atmospheric and low pressure and improvements found in germination rate and percentage of success. Seed water uptake by exposure to water vapor, although slightly greater for plasma treated seeds, did not justify the observed germination improvement. To identify other possible factors contributing to germination, the chemical changes experienced by outer parts of the seed upon plasma exposure have been investigated by X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM-EDX). XPS revealed that the outer layers of the Quinoa plasma treated seeds were highly oxidized and appeared enriched in potassium ions and adsorbed nitrate species. Simultaneously, SEM-EDX showed that the enrichment in potassium and other mineral elements extended to the seed pericarp and closer zones. The disappearance from the surface of both potassium ions and nitrate species upon exposure of the plasma treated seeds to water vapor is proposed as a factor favoring germination. The use of XPS to study chemical changes at seed surfaces induced by plasma treatments is deemed very important to unravel the mechanisms contributing to germination improvement.

Direct evidence for cell adhesion-mediated radioresistance (CAM-RR) on the level of individual integrin β1 clusters

The cellular interaction with the extracellular matrix (ECM) modulates many key processes such as proliferation, migration, differentiation and survival. In addition, cells cultured under 3D conditions in presence of an ECM display a marked radioresistance towards ionizing radiation (IR) in comparison to conventionally 2D cultured cells. This process, also known as "cell-adhesion-mediated-radio-resistance" (CAM-RR), has been linked to the chromatin structure that differs between cells cultured on stiff surfaces versus cell grown on soft planar supports or in 3D environments. As integrins are the key mediators of cell adhesion and mechanosensing, they originate the molecular signalling towards chromatin remodelling in response to a cell's microenvironment. We aimed to investigate this molecular origin that leads to CAM-RR by investigating the distribution of integrins at the single molecule level and show that cells cultured in 2D keep a lower fraction of integrin β1 in clusters and maintain a less defined cluster status than 3D cultured cells. Upon X-irradiation this nanoscale distribution of integrin β1 is disturbed at much lower dosages in 2D versus 3D cultured cells. Radioresistance is thus linked to the ability to maintain a well defined organization of integrins in clusters, making integrin distribution a potential drug target for radiosensitization.

Membrane Oxidation in Cell Delivery and Cell Killing Applications

Cell delivery or cell killing processes often involve the crossing or disruption of cellular membranes. We review how, by modifying the composition and properties of membranes, membrane oxidation can be exploited to enhance the delivery of macromolecular cargoes into live human cells. We also describe how membrane oxidation can be utilized to achieve efficient killing of bacteria by antimicrobial peptides. Finally, we present recent evidence highlighting how membrane oxidation is intimately engaged in natural biological processes such as antigen delivery in dendritic cells and in the killing of bacteria by antimicrobial peptides. Overall, the insights that have been recently gained in this area should facilitate the development of more effective delivery technologies and antimicrobial therapeutic approaches.

How Does Membrane Oxidation Affect Cell Delivery and Cell Killing?

The biophysical properties of cellular membranes intimately influence the delivery of cargoes into cells by cell-penetrating peptides (CPPs) and the bactericidal activity of antimicrobial peptides (AMPs). Here, we discuss how lipid oxidation creates important chemical and biophysical changes in membranes, and hypothesize about the observed synergy between oxidized membranes and membrane-active peptides.

Gas-liquid interfacial plasmas producing reactive species for cell membrane permeabilization

Gas-liquid interfacial atmospheric-pressure plasma jets (GLI-APPJ) are used medically for plasma-induced cell-membrane permeabilization. In an attempt to identify the dominant factors induced by GLI-APPJ responsible for enhancing cell-membrane permeability, the concentration and distribution of plasma-produced reactive species in the gas and liquid phase regions are measured. These reactive species are classified in terms of their life-span: long-lived (e.g., H₂O₂), short-lived (e.g., O₂^•−), and extremely-short-lived (e.g., ^•OH). The concentration of plasma-produced ^•OH_aq in the liquid phase region decreases with an increase in solution thickness (<1 mm), and plasma-induced cell-membrane permeabilization is found to decay markedly as the thickness of the solution increases. Furthermore, the horizontally center-localized distribution of ^•OH_aq, resulting from the center-peaked distribution of ^•OH in the gas phase region, corresponds with the distribution of the permeabilized cells upon APPJ irradiation, whereas the overall plasma-produced oxidizing species such as H₂O_2aq in solution exhibit a doughnut-shaped horizontal distribution. These results suggest that ^•OH_aq is likely one of the dominant factors responsible for plasma-induced cell-membrane permeabilization.