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Investigation of protein-ligand interactions in physiological conditions is crucial for better understanding of biochemistry because the binding stoichiometry and conformations of complexes in biological processes, such as various types of regulation and transportation, could reveal key pathways in organisms. Nanoelectrospray ionization mass spectrometry is widely used in studies of biological processes and systems biology. However, non-volatile salts in biological fluid may adversely interfere with nanoelectrospray ionization mass spectrometry. In this study, the previously developed method of induced nanoelectrospray ionization was used to facilitate in situ desalting of protein in solutions with high concentrations of non-volatile salts, and direct investigation of protein-ligand interactions for the first time. In situ desalting occurred at the tip of emitters within a short period lasting for a few to tens of milliseconds, enabling the maintenance of nativelike conditions compatible with mass spectrometry measurements. Induced nanoelectrospray ionization was driven by pulsed potential and exhibited microelectrophoresis effect in each spray cycle, which is not observed in conventional nanoelectrospray ionization because the continuous spray procedure is driven by direct current. Microelectrophoresis caused desalting through micron-sized spray emitters (1–20 μm), as confirmed experimentally with proteins in 100 mM NaCl solution. The method developed in this study has been further illustrated as a potential option for fast and direct identification of protein-ligand (small molecules or metal ions) interactions in complex samples. The results of this study demonstrate that the newly developed method may represent a reliable approach for investigations of proteins and protein complexes in biological samples.

Gold nanoparticles (GNPs) are an attractive nanomaterial for potential applications in therapy and diagnostics due to their capability to direct toward specific sites in the organism. However, when exposed to plasma, GNPs can interact with different biomolecules that form a dynamic nano-bio interface called a "protein corona" (PC). Remarkably, the PC could affect multiple biological processes, such as cell targeting and uptake, cytotoxicity, and nanoparticle (NP) clearance. The interaction of nanomaterials with plasmatic proteins has been widely studied under bulk conditions, however, under dynamic conditions, it has just recently been explored. Thus, to mimic a dynamic natural environment found in arteries and veins, microfluidic devices were used. In this work, gold nanorods (GNRs) were synthesized and conjugated with polyethylene glycol (PEG) to reduce their interaction with plasma proteins and increase their biocompatibility. Then, GNRs were functionalized with folic acid, a targeting ligand typically used to recognize tumor cells. The resulting nanosystem was exposed to fibrinogen (FB) to study the development and biological impact of PC formation through two strategies: bulk and laminar flow conditions. The obtained nanosystems were characterized by absorption spectrophotometry, DLS, laser Doppler microelectrophoresis, neutron activation analysis, circular dichroism spectroscopy and TEM. Finally, cell viability and cellular uptake assays were performed to study the influence of the PC on the cell viability and delivery of nanosystems.

Results of studying the electric polarizability of colloidal graphite particles in an aqueous 1 : 1 electrolyte solution at frequencies of 100 Hz to 2.5 MHz have been presented. The polarizability anisotropy, surface conductivity, and electrokinetic potential of graphite particles have been investigated in aqueous KCl solutions with concentrations lower than 0.2 mmol/L. The dispersion of polarizability anisotropy of graphite particles has been determined by the electrooptical method, while their electrokinetic potential has been measured by laser Doppler microelectrophoresis. It has been shown that, at low electric field frequencies, the particles are polarized as dielectric ones. The theory of polarizability of dielectric particles has been employed to calculate the surface conductivity of graphite particles as a function of KCl concentration. As the frequency is increased, the mechanism of conductive particle polarizability begins to dominate over the mechanism of dielectric particle polarizability. In the aforementioned range of KCl concentrations, the electrokinetic potential of the particles varies significantly weaker than their polarizability and lies in a range of 30–36 mV.

The influence of kaempferol (K), myricetin (M) and lipoic acid (LA) on the properties of natural erythrocytes, isolated from animal blood and biological membrane models (monolayers and liposomes) made of phosphatidylcholine (PC), cholesterol (CHOL), and sphingomyelin (SM), CHOL in a ratio of 10:9, was investigated. The Langmuir method, Brewster angle microscopy (BAM) and microelectrophoresis were used. The presented results showed that modification of liposomes with kaempferol, myricetin and lipoic acid caused changes in the surface charge density and the isoelectric point value. Comparing the tested systems, several conclusions were made. (1) The isoelectric point for the DPPC:Chol:M (~2.2) had lower pH values compared to lipoic acid (pH~2.5) and kaempferol (pH~2.6). (2) The isoelectric point for the SM-Chol with myricetin (~3.0) had lower pH values compared to kaempferol (pH~3.4) and lipoic acid (pH~4.7). (3) The surface charge density values for the DPPC:Chol:M system in the range of pH 2–9 showed values from 0.2 to −2.5 × 10−2 C m−2. Meanwhile, for the DPPC:Chol:K and DPPC:Chol:LA systems, these values were higher at pH~2 (0.7 × 10−2 C m−2 and 0.8 × 10−2 C m−2) and lower at pH~9 (−2.1 × 10−2 C m−2 and −1.8 × 10−2 C m−2), respectively. (4) The surface charge density values for the SM:Chol:M system in the range of pH 2–9 showed values from 0.5 to −2.3 × 10−2 C m−2. Meanwhile, for the DPPC:Chol:K and DPPC:Chol:LA systems, these values were higher at pH~2 (0.8 × 10−2 C m−2), and lower at pH~9 (−1.0 × 10−2 C m−2 and −1.8 × 10−2 C m−2), respectively. (5) The surface charge density values for the erythrocytes with myricetin in the range of pH 2–9 showed values from 1.0 to −1.8 × 10−2 C m−2. Meanwhile, for the erythrocytes:K and erythrocytes:LA systems, these values, at pH~2, were 1.3 × 10−2 C m−2 and 0.8 × 10−2 C m−2 and, at pH~9, −1.7 × 10−2 C m−2 and −1.0 × 10−2 C m−2, respectively.

Direct chemical profiling and protein identification from living single cells using mass spectrometry (MS) have been demonstrated to further our understanding of biological variability and differential susceptibility to several diseases and treatments. Despite the great challenge from extremely complicated cytoplasm, we recently proposed a versatile MS strategy to achieve direct mass spectrometric characterization of both proteins and metabolite-like small molecules directly from living cells or single cells. Although the capability to directly handle cell cytoplasm was presumably attributed to microelectrophoresis in our previous studies, the assumption had only been partially explored by some preliminary experiments. To better understand the mechanism, herein, we systematically characterized its separation behavior with a series of model compounds covering a wide range of molecular size. With the merit of in situ separation, microelectrophoresis herein has been further demonstrated as an attractive and alternative tool, which can potentially contribute to direct MS measurements of more protein interactions or metabolic pathways in living single cells or a few cells.

When creating new materials, surface modification is an effective means of controlling the characteristics and the colloidal properties of cellulose nanocrystals (CNC), thereby increasing its compatibility with composite matrices. In this paper, the CNC surface is modified in aqueous media by cyanoethyl groups, followed by the hydrolysis of grafted nitrile groups. Particles having a surface composition close to that of native cellulose (N-CNC) and particles with sulfated surfaces (S-CNC) are used. The influence of the functional composition of CNC, as well as that of temperature and the ratio of reagents on the modified particles is investigated. It is shown that under identical synthesis conditions, a higher degree of cyanoethylation can be achieved for N-CNC. Particles modified with only nitrile groups and those with a polyfunctional composition modified with amide and carboxyl groups are obtained. Atomic force microscopy (AFM) and X-Ray diffraction (XRD) data indicate the preservation of both the morphology and structure of CNC post modification. The modified CNC particles are characterized by elemental analysis, synchronous thermal analysis (STA) and Fourier-transform infrared (FTIR) spectroscopy. The thermal stability of the resulting particles is close to that of the starting materials but higher for N-CNC and its derivatives. The acid-base properties of the CNC surface are established using a combination of methods (photometric measurements), namely potentiometric titration, dynamic light scattering, and microelectrophoresis. It is shown that the aggregative stability of modified particles along with the activity and number of acid-base centers on their surface increases sharply after the hydrolysis of nitrile groups.

Models predicting wettability alteration of mineral-brine-oil interfaces during low-salinity-waterflooding (LSW) should account for the elevated temperatures typically found in oil reservoirs. For the first time, high temperature ζ-potential (zeta potential) data for silica are collected and used to interpret surface chemistries and interactions at reservoir-like conditions to predict temperature’s effect on wettability alteration. Mobility data for amorphous silica in varying NaCl(aq) concentrations at 25, 100, and 150 °C and neutral pH were obtained through microelectrophoresis experiments. Calculated ζ-potentials were fit with surface complexation model (SCM) parameters to predict electrical double layer (EDL) parameters based upon the Gouy-Chapman-Stern-Grahame (GCSG) model. ζ-potentials increased with increasing temperature (around 50% increase from 25 to 150 °C) and decreasing NaCl concentrations (10−1–10−4 mol kg−1). These trends, along with Derjaguin-Verwey-Landau-Overbeek (DLVO) theory, suggests that overall repulsive forces extend farther from the surface at low salinity and higher temperatures, implying greater wetting thickness/surface wettability in these environments. The resulting surface concentration calculations suggest that LSW is most impactful up to 10−2 mol kg−1 of salt, and that additional dilution below 10−3 mol kg−1 will negligibly impact oil recovery, particularly at reservoir temperatures above 100 °C. The analysis provides a framework for treating more complex reservoir systems, such as carbonates in multivalent brines.

The purpose is to study the capability of the electric light scattering to determine the point of zero charge of native protein macromolecules adsorbed on colloid particles at low ionic strength and without using buffers. The chosen protein and particles are cytochrome c (cytC, globular haemoproteid) and montmorillonite (MM, negatively charged plate-like crystal). The pH-dependence of the electric polarizability γ(pH) in the range pH 6–11 shows minimum which coincides with the isoelectric point determined by measuring the electrophoretic mobility μ(pH) of the cytC-MM particles.

Low-level laser therapy (LLLT) is widely used in clinical practice for treatment of various pathologies. It is assumed that LLLT impact on microcirculation is among the mechanisms underlying its therapeutic effect. The microcirculation disorder is observed in the pathogenesis of any inflammatory process and is significantly influenced by red blood cells (RBCs). On this point, studying the RBCs morphology under the influence of LLLT on alterated organism is of scientific interest and practical importance. The aim of the present study was to analyze the LLLT effect on morphokinetic parameters of RBCs in hyperadrenalinemia. The LLLT effect was analyzed on rats intraperitoneally injected with adrenaline hydrochloride solution (0.1 mg/kg). As the comparison groups, the effects of LLLT, adrenaline, or saline injection as well as the parameters of intact animals were studied. LLLT was applied on the occipital region of rats for 10 min. The light irradiation with pulse frequency 415 Hz at 890 nm wavelength and average power density in the plane of the output window at 193 μW/cm2 was used. The dynamics of morphological characteristics of RBCs was studied by phase interference microscopy; the RBC electrophoretic mobility was tested by microelectrophoresis technique; photometric analyses of the RBCs amount, hemoglobin content, and osmotic fragility were performed. The adrenaline injection resulted in a significant increase in the amount of RBC pathological forms and a decrease in discocytes and normocytes by more than 50%. An increase in the optical density of RBC phase portraits, a decline in osmotic resistance, and electronegativity of RBC membranes and a reduction of their number in peripheral blood were also registered. The revealed effects persisted for 1 week after the adrenaline administration. LLLT did not significantly impact on the RBC parameters 1 h after adrenaline injection. However, a day later, LLLT reduced the severity of the adrenaline effect on RBSs, which was manifested in a decreased amount of the pathological forms of RBCs, restored RBC phase portraits, higher electrophoretic mobility and osmotic resistance, and RBSs amount in peripheral blood restored up to the level of intact animals. We suppose that the mechanism of LLLT action is realized both at cellular level through the laser radiation effect on RBC membranes, and at systemic level through the activation of stress-realizing systems of the organism with subsequent limitation of inflammatory response.

The purpose is to determine the isoelectric point (IEP) pIμ of cytochrome c (cytC, a globular haemoproteid) adsorbed on montmorillonite (MM, plate-like colloid particles) by microelectrophoresis and to compare the pIμ value with pIf9.44 measured by isoelectric focusing in gel with covalently linked ampholytes, and with pInz10.0-10.6 of free cytC globule calculated by three programs for pH-dependent net charge nz using the crystallographic structure of cytC. The pH-dependence of the electrophoretic mobility μ(pH) in the range pH 6-11 shows out that IEP of cytC-MM particles appears at pH 9.35. The near courses of μ(pH) and nz(pH) reveal that the pH-independent negative charge of the MM substrate is hydrodynamically shielded by the adsorbed protein globules. The nearness of IEP and pIf allows attributing IEP value of cytC-MM particles to the isoelectric point pIμ of cytC. A short survey for pI of cytC reported in the literature since 1941 shows out that pI is dispersed in the range pH 9.0-10.65 although cytC is used now as pIf marker with well known IEP; the reason for that and the imperfections of the employed methods are discussed.

The pH-dependent surface charging of tellurium (IV) oxide has been studied. The isoelectric point (IEP) of tellurium (IV) oxide was determined by microelectrophoresis in various 1-1 electrolytes over a concentration range of 0.001–0.1 M. In all electrolytes studied and irrespective of their concentration the zeta potential of TeO2 was negative over the pH range 3–12. In other words the IEP of TeO2 is at pH below 3 (if any). TeO2 specifically adsorbs ionic surfactants, and their presence strongly affects the zeta potential. In contrast the effect of multivalent inorganic ions on the zeta potential of TeO2 is rather insignificant (no shift in the IEP). In this respect TeO2 is very different from metal oxides.

Legionella pneumophila cell surface hydrophobicity and charge are important determinants of their mobility and persistence in engineered water systems (EWS). These surface properties may differ depending on the growth phase of L. pneumophila resulting in variable adhesion and persistence within EWS. We describe the growth-dependent variations in L. pneumophila cell surface hydrophobicity and surface charge using the microbial adhesion to hydrocarbon assay and microelectrophoresis, respectively, and their role in cell adhesion to stainless steel using a quartz crystal microbalance with dissipation (QCM-D) monitoring instrument. We observed a steady increase in L. pneumophila hydrophobicity during their lifecycle in culture media. Cell surfaces of stationary phase L. pneumophila were significantly more hydrophobic than their lag and midexponential counterparts. No significant changes in L. pneumophila cell surface charge were noted. Morphology of L. pneumophila remained relatively constant throughout their lifecycle. In the QCM-D study, lag and exponential phase L. pneumophila weakly adhered to stainless steel surfaces resulting in viscoelastic layers. In contrast, stationary phase bacteria were tightly and irreversibly bound to the surfaces, forming rigid layers. Our results suggest that the stationary phase of L. pneumophila would highly favour their adhesion to plumbing surfaces and persistence in EWS.

Background Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents. Objectives This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments. Results Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 μg/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM. Conclusions Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.

Nanoparticles with specific properties and functions have been developed for various biomedical research applications, such as in vivo and in vitro sensors, imaging agents and delivery vehicles of therapeutics. The development of an effective delivery method of nanoparticles into the intracellular environment is challenging and success in this endeavor would be beneficial to many biological studies. Here, the well-established microelectrophoresis technique was applied for the first time to deliver nanoparticles into living cells. An optimal protocol was explored to prepare semiconductive quantum dots suspensions having high monodispersity with average hydrodynamic diameter of 13.2-35.0 nm. Micropipettes were fabricated to have inner tip diameters of approximately 200 nm that are larger than quantum dots for ejection but less than 500 nm to minimize damage to the cell membrane. We demonstrated the successful delivery of quantum dots via small electrical currents (-0.2 nA) through micropipettes into the cytoplasm of living human embryonic kidney cells (roughly 20-30 μm in length) using microelectrophoresis technique. This method is promising as a simple and general strategy for delivering a variety of nanoparticles into the cellular environment.

Elucidating electrokinetic stability by which surface charges regulate toxins interaction with erythrocytes is crucial for understanding the cell functionality. Electrokinetic properties of human erythrocytes upon treatment of Vipoxin, phospholipase A2 (PLA2) and Vipoxin acidic component (VAC), isolated from Vipera ammodytes meridionalis venom were studied using particle microelectrophoresis. PLA2 and Vipoxin treatments alter the osmotic fragility of erythrocyte membranes. The increased stability of cells upon viper toxins is presented by the increased zeta potential of erythrocytes before sedimentation of cells during electric field applied preventing the aggregation of cells. Lipid peroxidation of low dose toxin-treated erythrocytes shows reduced LP products compared to untreated cells. The apparent proton efflux and conductivity assays are performed and the effectiveness PLA2 > Vipoxin>VAC is discussed. The reported results open perspectives to a further investigation of the electrokinetic properties of the membrane after viper toxins treatment to shed light on the molecular mechanisms driving the mechanisms of inflammation and neurodegenerative diseases

With the growing interest of the medical industry in biocompatible nanoparticles (NPs), the current synthetic methods should be adapted to appropriate demands (toxicity, scalability, etc.). Most applications require colloidal systems to be stable not only in water but also in vivo, which represents a major challenge. In this study, biocompatible Ta2O5 NPs were synthesized by a solvothermal method avoiding toxic reagents, and surfactant-free stable hydrosols were obtained and used for computed tomography (CT) imaging. The small hydrodynamic size (2 nm) and colloidal stability of primary NPs were studied by dynamic light scattering (DLS). The particles were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analysis to confirm their structure and purity. To develop a stable hydrosol preparation protocol, the influence of pH and ultrasonication duration on the stability of Ta2O5 sols was analyzed by DLS and microelectrophoresis. To enhance the understanding of NP behavior in vivo, sol stability in conditions close to physiological (NaCl solutions) was studied in a pH range of 3-9. Hydrosols prepared by the proposed protocol were stable for at least 6 months and exhibited negligible cytotoxicity. Ta2O5 NPs also showed high CT contrast both in theoretical calculations and in vivo (rat gastrointestinal tract).

Nanoparticles with desirable properties and functions have been actively developed for various bio-medical research, such as in vivo and in vitro sensors, imaging agents and delivery vehicles of therapeutics. However, an effective method to deliver nanoparticles into the intracellular environment is a major challenge and critical to many biological studies. Current techniques, such as intracellular uptake, electroporation and microinjection, each have their own set of benefits and associated limitations (e.g., aggregation and endosomal degradation of nanoparticles, high cell mortality and low throughput). Here, the well-established microelectrophoresis technique is applied for the first time to deliver nanoparticles into target cells, which overcomes some of these delivery difficulties. Semiconductive quantum dots, with average hydrodynamic diameter of 24.4 nm, have been successfully ejected via small electrical currents (−0.2 nA) through fine-tipped glass micropipettes as an example, into living human embryonic kidney cells (roughly 20 - 30μm in length). As proposed by previous studies, micropipettes were fabricated to have an average tip inner diameter of 206 nm for ejection but less than 500 nm to minimize the cell membrane damage and cell distortion. In addition, delivered quantum dots were found to stay monodispersed within the cells for approximately one hour. We believe that microelectrophoresis technique may serve as a simple and general strategy for delivering a variety of nanoparticles intracellularly in various biological systems.

Thylakoid membranes of photosynthetic plant chloroplasts are involved in a wide range of energy producing pathways. Their stacking can be employed in order to provide increased surface area for biocatalytic purposes. Here we probe the aggregate formation of higher plants' thylakoids using low-molecular poly-l-lysine as an electrostatic polymer linker in low ionic strength media. Microelectrophoresis, actinic light scattering, millisecond-delayed fluorescence and free radical production of thylakoid membranes are measured and analyzed in the presence of the cationic polypeptide to track its influence on the surface electrical properties, the electron-transport processes and the proton gradient accumulation across membranes. Enhanced proton gradient in polylysine-treated thylakoids is obtained upon illumination due to alterations of the proton intake across the membrane resulting from the non-specific electrostatic interactions of the cationic polypeptide with thylakoids. We report lower rates of lipid peroxidation in polylysine-treated thylakoids measured both in the dark and under illumination in salt-free medium. The gained insight on the effect of polycations on photosynthetic membranes may be used in future developments of thylakoid-based approaches for energy transfer applications.

The characteristics of the wetting process of the porous surface of silica gel when penetrated by base liquids (water and n-octane), ethanol and stable drug systems (naproxen, ibuprofen and cyclosporine A), as biologically active substances in two ethanol concentrations, were determined by the wetting rate vs. time. The tests were performed for contacted and non-contacted plates with the vapours of the wetting liquid. Thin-layer liquid chromatography was used to determine the penetration rate of the SiO2-coated plates, taking into account the linear dependence consistent with the Washburn equation. Additionally, the changes in the adhesive tension ΔG were determined for the tested drugs. Drug stability tests were conducted using the dynamic light scattering technique and microelectrophoresis. The penetration time of the plate depends on the properties and structure of the wetting liquid droplets. The types of interactions (dispersive, electrostatic and hydrogen bonding) formed between the silanol surface groups of the silica gel and the groups contained in the adsorbate particles are also very important factors. The greater the impact force, the slower the wetting process due to the strong penetration of the liquid into the pores of the substrate. The characteristics of the drug wetting/stability process may contribute to the development of their new forms, creating delivery systems with greater efficiency and lower side effects.

An online combination of isotachophoresis (ITP) and capillary zone electrophoresis (CZE) was employed on a microchip with a column-coupling technology for the determination of homocysteine in various body fluids. ITP with its high concentration ability was used as a sample pretreatment and injection technique for CZE, which facilitated the rapid and sensitive determination of homocysteine. The resolution of the analyte from other constituents present in real complex samples was enhanced by discrete spacers, which were added to the injected sample. A solid-phase microextraction (SPME) pretreatment technique based on silver- and barium-form resins was used prior to the ITP-CZE analysis to remove high concentrations of chloride and sulfate naturally present in the analyzed samples. The combination of the micropretreatment and microelectrophoresis techniques facilitated the determination of trace concentrations of homocysteine in samples of urine and saliva

Stimuli-responsive particles of crosslinked poly-N-vinylcaprolactam and poly-N,N-(dimethylamino)ethyl methacrylate (microgels) have been synthesized in oil-in-water emulsion without using of emulsifier. Dispersions of spherical particles of about 200 nm in size rather narrowly distributed as defined by dynamic light scattering and TEM microscopy were stable in time in case of 50 and more mol. % of N,N-(dimethylamino)ethyl methacrylate. Zeta potential, measured by laser Doppler microelectrophoresis, revealed negative (-4.4 mV) and low positive (+6.6 mV) charges on particle surface. Positive charge in the case of 70 mol. % of N,N-(dimethylamino)ethyl methacrylate is provided by the protonated nitrogen atom of the monomer on the interphase surface. Low positive and negative instead of expected more positive value of zeta potential can be explained by specific sorption SO42- ions on the particle surface during the polymerization, which are formed by decomposition of initiator K2S2O8. Investigation of the effect of pH on the stability and particles size of the microgel with 50 mol. % of N,N-(dimethylamino)ethyl methacrylate showed that they remain stable in a wide range of pH values. An increase in the size of particles caused by polyelectrolyte swelling is observed in an acidic medium. Synthesized microgels exhibit thermosensitive properties. It is shown that, with an increase of N,N-(dimethylamino)ethyl methacrylate units, the volume phase transition temperature shifts to a lower temperatures, while the degree of particle compression is decreasing. It should also be noted that the change in particles size under the effect of temperature is reversible.

The aim of research was first, to study the interactions between components for finding out how pH effects on ζ-potential, dewatering rate and retention of TiO2/MCC mixtures with/without titanyl sulphate in order to find a way to titanyl sulphate hydrolysis in a papermaking process. The maximum heterocoagulation interactions between TiO2, MCC and TiOSO4 were revealed in the pH range 4.4–5.6. Second, handsheets made from refined chemical pulp, titanyl sulphate and TiO2 at pH 4.4 were investigated. The handsheets were formed and studied conventionally and with scanning electron microscopy (SEM). It was shown that titanyl sulphate hydrolysis leads to formation of translucent polymer film covering the fibres and TiO2 particles. The maximum first-pass ash retention reached is lower than its values usually obtained with an organic polymer. Addition of titanyl sulphate led to higher strength, but lowered opacity and brightness compared to a reference sample. The use of low dosage of titanyl sulphate together with a filler improved air permeability. As there exist certain advantages/disadvantages of titanyl sulphate application, extended research is needed to find suitable conditions for its applying to mass paper and board grades production.

A number of new membrane anchors based on water-soluble aminoglycerides with geraniol fragments have been synthesized. A biomimetic approach was used based on the design of meroterpenes structurally similar to archaeal lipids. Turbidimetry and laser Doppler microelectrophoresis showed that the synthesized compounds were incorporated into unilamellar dipalmitoylphosphatidylcholine (DPPC) vesicles.

As a bioactive and functional polysaccharide, sea cucumber fucoidan has received increasing attention. Chain conformation and physicochemical properties of fucoidan extracted from Thelenota ananas (Ta-FUC) was investigated by utilizing HPSEC-MALLS-Visc-RI, microelectrophoresis and steady shear measurements. The conformation parameter α s (0.61 ± 0.02), the Mark-Houwink-Kuhn-Sakurada exponent α η (0.92 ± 0.01), α h (0.64 ± 0.01) and the Smidsrod-Haug stiffness parameter B (0.036 ± 0.010) consistently manifested that Ta-FUC adopted a semi-flexible coil conformation in NaCl solution. Based on a wormlike cylinder model, stiffness parameters, including persistence length q (13.27 ± 0.80 nm) and cylinder diameter d (0.79 nm), were calculated. This polysaccharide demonstrated shear-thinning rheological behaviour, and critical concentration from dilute to semidilute concentration regime was determined as 3.6 mg/ml. Ta-FUC exhibited as a negative polyelectrolyte in wide pH and ionic strength ranges. These molecular characteristics and physicochemical properties would facilitate further application of Ta-FUC as a functional ingredient in food.

Amyloid β (Aβ) peptide contributes to Alzheimer’s disease by a yet unidentified mechanism. In the brain tissue, Aβ occurs in various forms, including an undecapeptide Aβ25-35, which exerts a neurotoxic effect through the mitochondrial dysfunction and/or Ca2+-permeable pore formation in cell membranes. This work was aimed at the biophysical characterization of membrane binding and pore formation by Aβ25-35. Interaction of Aβ25-35 with anionic and zwitterionic membranes was analyzed by microelectrophoresis. In pore formation experiments, Aβ25-35 was incubated in aqueous buffer to form oligomers and added to Quin-2-loaded vesicles. Gradual increase in Quin-2 fluorescence was interpreted in terms of membrane pore formation by the peptide, Ca2+ influx, and binding to intravesicular Quin-2. The kinetics and magnitude of this process were used to evaluate the rate constant of pore formation, peptide–peptide association constants, and the oligomeric state of the pores. Decrease in membrane anionic charge and high...

The flocculation by compositions, based on synthetic poly-1,2-dimethyl-5-vinylpyridinium methyl sulfate (K1),poly-trimethyl(methacryloyloxyethyl)-ammonium methyl sulfate (K2) and natural polyelectrolyte (chitosan, Cs) using an aqueous kaolin dispersion was studied. Floccule formation parameters and sedimentation rates were determined by optical microscopy, turbidimetry and microelectrophoresis. The synergistic effect is observed using the polyelectrolyte compositions, it appears in 40% increase of the floccule sedimentation rates and promotes the formation of two times more dense floccules compared to using individual flocculants. The synergistic effect of two cationic polyelectrolytes was confirmed by the flocculation research results in aqueous-salt solutions at various NaCl salt concentrations. A study of the behavior of the two polyelectrolytes macromolecules in solution was performed to explain the observed synergistic effect. The decrease of macromolecules hydrodynamic radius in the joint presence of two like-charged polyelectrolytes was revealed by the capillary viscometry, dynamic and static light scattering. It was determined, that the behavior of two cationic polyelectrolytes in the common solution determines the character of their behavior on the dispersed phase surface in the flocculation process.

The electrophoretic mobility and the zeta potential (ζ) of fluorescently labeled colloidal silica rods, with an aspect ratio of 3.8 and 6.1, were determined with microelectrophoresis measurements using confocal microscopy. In the case where the colloidal particles all move at the same speed parallel to the direction of the electric field, we record a xyz-stack over the whole depth of the capillary. This method is faster and more robust compared to taking xyt-series at different depths inside the capillary to obtain the parabolic flow profile, as was done in previous work from our group. In some cases, rodlike particles do not move all at the same speed in the electric field, but exhibit a velocity that depends on the angle between the long axis of the rod and the electric field. We measured the orientation-dependent velocity of individual silica rods during electrophoresis as a function of κa, where κ-1 is the double layer thickness and a is the radius of the rod associated with the diameter. Thus, we determined the anisotropic electrophoretic mobility of the silica rods with different sized double layers. The size of the double layer was tuned by suspending silica rods in different solvents at different electrolyte concentrations. We compared these results with theoretical predictions. We show that even at already relatively high κa when the Smoluchowski limiting law is assumed to be valid (κa > 10), an orientation dependent velocity was measured. Furthermore, we observed that at decreasing values of κa the anisotropy in the electrophoretic mobility of the rods increases. However, in low polar solvents with κa < 1, this trend was reversed: the anisotropy in the electrophoretic mobility of the rods decreased. We argue that this decrease is due to end effects, which was already predicted theoretically. When end effects are not taken into account, this will lead to strong underestimation of the experimentally determined zeta potential. (Figure Presented).

The objectives of this study were to characterize the physicochemical properties and evaluate the antimicrobial capacity of polyelectrolyte complexes (PECs) consisting of cationic epsilon‐polylysine·HCl (e·PL·HCl) and anionic high‐methoxyl pectin (HMP). The physicochemical properties were analysed by microelectrophoresis (ζ‐potentials), mean diameter (Z‐average), differential scanning calorimetry (DSC) and Fourier‐transform infrared spectroscopy (FTIR). Experimental results indicated that PECs have different physicochemical properties or behaviour dependent on e·PL·HCl/HMP mass ratio and e·PL·HCl concentration. The antimicrobial activity was tested by minimal inhibitory concentration (MIC), which showed that the PECs had effective antimicrobial activity. Finally, this study found that using an appropriate proportion of PECs could not only avoid the formation of undesirable precipitates resulting from the interaction between e·PL·HCl and anionic components within the soymilk systems, but also could extend their shelf‐life. PRACTICAL APPLICATIONS: e‐polylysine and its derivatives would interact with anionic components within foods and beverages through ionic adsorption resulting in forming undesirable precipitates, which will cause the decrease in its antimicrobial activity and the loss of food nutrients. In this study, HMP with e·PL·HCl were used to form polyelectrolyte complexes as antimicrobial delivery systems and further reveal their physicochemical and antimicrobial properties. They could be satisfactorily applied in soymilk systems without sacrificing effective antimicrobial activity of e·PL·HCl as well as avoiding undesirable precipitation. This information is expected to practical into protein‐containing beverage systems to extend their shelf‐life.

Complex coacervation is a useful approach for creating biopolymer-based colloidal particles for the oral delivery of bioactives, such as nutraceuticals, vitamins, and pharmaceuticals. In this study, we examined the possibility of using anionic ɣ-poly-glutamic acid (PGA) and cationic ɛ-poly- l -lysine (PLL) to form polyelectrolyte complexes. Initially, the formation and properties of the complexes were characterized using visual observations, UV–visible spectrophotometry, microelectrophoresis (ζ-potential), and isothermal titration calorimetry (ITC). The impact of pH, ionic strength, temperature, and polymer ratio on complex formation was examined. The electrostatic complexes formed had a 1:4 mass ratio of polyanion-to-polycation at saturation (pH 7.4). The surface potential and aggregation stability of the complexes was highly dependent on solution pH (2–12), which was attributed to alterations in the electrical characteristics of the two polyelectrolytes. In particular, insoluble complexes were formed under pH conditions where there was a strong electrostatic attraction between the two polyelectrolytes, whereas soluble complexes were formed when there was only a weak attraction. The addition of salt (≥20 mM NaCl) promoted aggregation of the complexes, presumably due to screening of the electrostatic interactions between them. Conversely, temperature (25–90 °C) did not have a major impact on the stability of the complexes. These results may be useful for the design of effective oral delivery systems for bioactive agents in foods and other products.

Divalent ions, in particular calcium ions, constitute important macroelements in living organisms. They are also found in cell membranes, i.e., ensuring their stabilization or participating in synaptic transmission of nerve impulses. The aim of this work is to describe the interactions of divalent ions, such as Ca2+, Ba2+, and Sr2+, in electrolytes with the functional groups on the surface of liposomes formed from phosphatidylcholine (PC). Microelectrophoresis is used to determine the surface charge density as a function of pH. The interactions between ions found in solution and the functional groups of PC are described with the use of a seven-equilibrium mathematical model. Using this model along with experimental data on the charge density of the membrane surface, the association constants characterizing this equilibrium are determined. These parameters are used to calculate the theoretical model curves. The validity of the proposed model is confirmed by comparing the theoretically calculated changes in charge density on the liposome surface with the experimental results.

In this paper, we examined the effect of adsorbed monovalent ions on the surface charge of liposomal membranes formed from neutral (sphingomyelin), anionic (phosphatidylinositol) lipids mixed in various ratios. The surface charge density of the membrane was determined from electrophoretic mobility measurements at various pHs of solution. A four-quilibria model describing adsorption of ions on the sphingomyelin (SM) membrane and a two-equilibria model describing adsorption of ions on the phosphatidylinositol (PI) membrane was presented. We proposed a mathematical model for characterizing these equilibria. Using these models, together with experimental data of the membrane surface charge density, we determined association constants characterizing the equilibria. The correctness of the proposed model was proven by comparing the theoretical charge variation curves for SM and PI membranes with the experimental date.

The importance of fungicides uses to maintain healthy crops and reliable, high-quality yields poses environmental issues due to the water and soil contaminations. The montmorillonite is known as efficient adsorbent for many pesticides, while the organo modification enabled to use them in wider range of applications. In this study, the fungicide fludioxonil (FDX) was adsorbed on raw and organo-modified Patagonian montmorillonite. The effects of the organo treatment as well as the FDX adsorption on the surface properties were investigated by X-ray diffraction, microelectrophoresis and inverse gas chromatography. The importance of the organo treatment was revealed both for the changes in the surface properties (dispersive component of the surface energy, nanoroughness and surface acidity as well as zeta-potential) and for the adsorption of FDX as it enabled increase two times respect to the pristine montmorillonite. Fil: Flores, Federico Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Gamba, Martina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Torres Sanchez, Rosa Maria. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; Argentina Fil: Brendlé, Eric. Adscientis; Francia Fil: Brendlé, Jocelyne. Adscientis; Francia

Interactions of alkali metal cations (Li+, Na+, K+, Cs+) with phosphatidylcholine (PC) liposomal membranes were investigated through experimental studies and theoretical considerations. Using a microelectrophoresis technique, charge densities of experimental membrane surfaces were measured as a function of the pH of electrolyte solutions. Equilibria between the PC liposomal membranes and monovalent ions were mathematically analyzed and described quantitatively through a previously proposed theoretical model. Association constants between functional groups of PC and the studied ions were determined and used to define theoretical curves of membrane surface charge density versus pH. Theoretical and experimental data were compared to verify the model. The PC membrane was found to have the highest affinity for lithium ions, among the ions tested.

The sperm membrane undergoes extensive surface remodeling as it matures in the epididymis. During this process, the sperm is encapsulated in an extensive glycocalyx layer, which provides the membrane with its characteristic negative electrostatic charge. In this study, we develop a method of microelectrophoresis and standardize the protocol to isolate sperm with high negative membrane charge. Under an electric field, the percentage of positively charged sperm (PCS), negatively charged sperm (NCS), and neutrally charged sperm was determined for each ejaculate prior to and following density gradient centrifugation (DGC), and evaluated for sperm DNA damage, and histone retention. Subsequently, PCS, NCS, and neutrally charged sperm were selected using an ICSI needle and directly analyzed for DNA damage. When raw semen was analyzed using microelectrophoresis, 94 % were NCS. In contrast, DGC completely or partially stripped the negative membrane charge from sperm resulting PCS and neutrally charged sperm, while the charged sperm populations are increased with an increase in electrophoretic current. Following DGC, high sperm DNA damage and abnormal histone retention were inversely correlated with percentage NCS and directly correlated with percentage PCS. NCS exhibited significantly lower DNA damage when compared with control (P

Stable highly concentrated TiO2 sol has been synthesized using binary titanyl ammonium sulfate monohydrate, (NH4)2TiO(SO4)2 · H2O. Treatment of the sol with an ammonia solution has yielded a stable hydrogel, which, after being dried, is transformed into a TiO2 xerogel. Study of the structure-related sorption and crystalline-chemical properties of the synthesized xerogel has shown that it represents a semicrystalline micro/mesoporous material with a rather developed specific surface area (Ssp = 120 m2/g). According to potentiometric titration data, the point of zero charge (PZC) of this material is located at pH 3.9. Measurements of the electrophoretic mobility (by microelectrophoresis) of TiO2 xerogel particles in solutions of HCl, NaOH, and salts of mono-, bi-, and trivalent cations have shown that (1) the isoelectric point (IEP) of the particles lies in the vicinity of pH 6.2, i.e., at a much higher pH than that for PZC; (2) the presence of increasing amounts of 1: 1 and 2: 1 electrolytes causes a gradual and a dramatic reduction in the ζ potential of the particles, respectively; and (3), in the presence of an electrolyte with a trivalent counterion, the surface charge is reversed. The behavior of TiO2 xerogel in an electric field is similar to that of lyophobic particles, with the difference that there is no maximum in the ζ potential versus 1: 1 electrolyte concentration dependence and the measured IEP of the xerogel is much higher than its PZC. Possible reasons for this discrepancy have been discussed.

Equilibria between the membranes of erythrocytes as well as thrombocytes and solution ions in fatal accidental hypothermia were analyzed using a theoretical four-equilibria model. The model was developed to determinate parameters characterizing cell membrane-surrounding ion interactions: the total surface concentrations of both acidic and basic groups C A, C B, and association constants K AH, K BOH. Knowledge of these parameters was necessary to calculate the theoretical values of surface charge density. The model was validated by curve-fitting the experimental data points to simulated data generated by the model. The experimental and theoretical surface charge density values agree at pH 2-8, at higher pH the deviation was observed.

This Review describes how in the period 1940-1959 cell electrophoresis (in the earlier literature often referred to as 'microelectrophoresis') was used to explore the surface chemistry of cells. Using the erythrocyte as a suitable model for the study of biological membranes, the early investigators were agreed on the presence of negatively charged groups at the surface of this cell. The contemporary dogma was that these were phosphate groups associated with phospholipids. Work in the 1960s, particularly on changes in the electrokinetic properties of erythrocytes following treatment with proteolytic enzymes, lead to the realization that the negatively charged groups at the red cell surface are predominantly due to sialic acids carried on glycoproteins. It quickly became apparent from cell electrophoresis that sialic acids have a ubiquitous presence on the surface of animal cells. This finding required that any complete model of the plasma membrane must include glycosylated molecules at the cell periphery, thus laying the foundations for the field termed 'Glycobiology of the Cell Surface'.

Clinoptilolite, an abundant and low cost natural zeolite, activated by sulphuric acid has been shown to be useful for treating coal seam gas (CSG) co-produced saline water. This paper aims to further examine the effect of the acid activation on changes in physicochemical properties of clinoptilolite which underpin the treatment of CSG saline water by clinoptilolite. Microelectrophoresis was applied to measure surface (zeta) potential of clinoptilolite particles before and after the acid activation as function of pH. The change in the surface potential was theoretically analysed applying the theory on the electrical double layers at solid-solution interfaces. The proton donor–acceptor reactions occurring simultaneously on amphoteric alumina and silica sites of clinoptilolite were considered. The mass balances were applied to link the zeolite active sites with the zeolite charge and potential. Comparing the model with the experimental data reveals the important role of the dealumination process occurred by the acid activation. The dealumination is the main reason for the increase in the surface charge and cation exchange capacity of clinoptilolite after the acid activation due to the increased defects in the crystal structure/lattice, which result in increasing numbers of charge vacancies. These results support our previous findings on the effectiveness of the acid activation of clinoptilolite in treating saline CSG co-produced water.

Reported values for the acid dissociation constant (p K a) of the saturated fatty acids show a wide range, depending on their method of measurement. Although the p K a values of the shorter chain saturated fatty acids are generally recognised to be approximately 4.5–5.0, p K a values for the longer chain fatty acids have been reported to be much higher, up to pH 10. It is the purpose of this study to investigate the values of p K a measured using microelectrophoresis for saturated fatty acids with chain lengths between C10 and C18. This returned an average p K a value of 4.0 for these saturated fatty acids. By the method of measurement, this value should be considered as the surface p K a value as opposed to bulk p K a values. The graphs of mobility vs. pH showed isoelectric points between 2 and 3, with the existence of positive surfaces on the particles of fatty acids confirmed. Some examples of the relevance of p K a values for saturated fatty acids in the flotation of non-sulphide minerals have also been given.

In this examination, we investigated the effect of lipoic acid (LA) on the properties of biological membrane models (monolayers, bilayers, and liposomes) formed from phosphatidylcholine (PC) or phosphatidylserine (PS) using the Langmuir, microelectrophoresis, and interfacial tension methods. The Langmuir technique allowed us to calculate the &pi, &ndash, A isotherms and determine the molecular surface areas of pure and mixed monolayers. Using mathematical equations, we established that LA and the lipids formed complexes at a 1:1 ratio. The interfacial tension method was based on Young and Laplace&rsquo, s equation. We assumed the formation of a 1:1 complex in the PC&ndash, LA system. Using the mathematical relationships, we derived the parameters characterizing the resulting complex, i.e., the surface occupied by the complex and the interfacial tension and stability constant of the formed complex. The microelectrophoretic method was used to determine the dependence of the zeta potential of the lipid membranes as a function of the pH (pH 2 to 10) of the electrolyte solution. The results indicate that modification of PC or PS membranes with LA affects changes in the zeta potential and the isoelectric point values.

Solder paste dispensing is a key process in the electronics assembly. The increased global demand for smaller, lighter, faster and cheaper assemblies drives the electronics industry to use dispensers with finer apertures. However, reduction in the aperture size of dispensers faces the industry with increased clogging of dispensers and incomplete transfer of paste to the printed circuit board (PCB) pads. One factor contributing to the clogging of dispensers is the agglomeration of the solder powder suspensions which depends on the electrokinetic behavior of the particles. When suspensions are close to the point of no charge, wherein zeta potential is equal to zero, the particles tend to agglomerate. This work focuses on the determination of the zeta potential of Sn, SAC305 and PbSn5Ag2.5 suspensions in isopropyl alcohol (IPA) through microelectrophoresis. The effect of acid, base and flux additives were studied. Results showed that the zeta potential of the solder suspensions are negative in pure IPA and charge reversal occurs in both acidic and basic region. In systems containing flux additives, the zeta potential of the suspensions is highly dependent on the type efflux. FTIR spectroscopy, conductivity measurement, and surface analysis was done in order to explain the observed electrokinetic behavior.

Interactions between trivalent metal ions (Al3+, In3+, La3+) and phosphatidylcholine (PC) liposomes are studied by microelectrophoresis. The dependence of the PC membrane surface charge density and zeta potential on $p{\rm H}$ ( $p{\rm H}$ range from 2 to 10) of the aqueous metal chloride solutions is determined. The obtained results indicate the adsorption of Al3+, In3+ and La3+ ions on phosphatidylcholine model membranes, leading to changes in the electrical properties of the membranes. The theoretical considerations on equilibria occurring between phosphatidylcholine liposomal membrane and trivalent metal ions are presented. A mathematical model describing the interactions in a quantitative way is proposed.

Background: Cationic solid lipid nanoparticles (SLNs) have been given considerable attention for therapeutic nucleic acid delivery owing to their advantages over viral and other nanoparticle delivery systems. However, poor delivery efficiency and complex formulations hinder the clinical translation of SLNs. Aim: The aim of this study was to formulate and characterize SLNs incorporating the cholesterol derivative cholesteryl oleate to produce SLN-nucleic acid complexes with reduced cytotoxicity and more efficient cellular uptake. Methods: Five cholesteryl oleate-containing formulations were prepared. Laser diffraction and laser Doppler microelectrophoresis were used to evaluate particle size and zeta potential, respectively. Nanoparticle morphology was analyzed using electron microscopy. Cytotoxicity and cellular uptake of lipoplexes were evaluated using flow cytometry and fluorescence microscopy. The gene inhibition capacity of the lipoplexes was assessed using siRNAs to block constitutive luciferase expression. Results: We obtained nanoparticles with a mean diameter of approximately 150-200 nm in size and zeta potential values of 25-40 mV. SLN formulations with intermediate concentrations of cholesteryl oleate exhibited good stability and spherical structures with no aggregation. No cell toxicity of any reference SLN was observed. Finally, cellular uptake experiments with DNA- and RNA-SLNs were performed to select one reference with superior transient transfection efficiency that significantly decreased gene activity upon siRNA complexation. Conclusion: The results indicate that cholesteryl oleate-loaded SLNs are a safe and effective platform for nonviral nucleic acid delivery., We are grateful to many colleagues for their helpful suggestions, critical discussions, and comments. We thank Jose Alcami and Mayte Coiras (National Microbiology Center, Majadahonda, Madrid, Spain) for the TZM-bl cells. This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (grant number BFU2014-54660-R) and the Andalusian Government (Excellence Project BIO-2515/2012) to CS and from the Spanish Ministry of Economy and Competitiveness (grant number BFU2016-79699-P) to CHM. Support from the European Region Development Fund (ERDF [FEDER]) is also acknowledged. MSP was supported by a fellowship from the Spanish Ministry of Education (FPU Program [Training Program for Academic Staff]).

We examined the adsorption of Na+, Cl−, H+, and OH− ions on phosphatidylcholine-cardiolipin liposomal membrane surfaces using both experimental and theoretical approaches. The dependence of the membrane surface charge density on the pH of the electrolyte solution was determined using microelectrophoresis. A mathematical model comprising eight equilibria was formulated to describe the adsorption of the electrolyte ions. Combination of this model with experimental surface charge density values enabled the determination of association constants. From the good agreement between the experimental and theoretical data, we can conclude that the assumed model is compatible with the experimental data.

In the present study, particular emphasis was put on the effects of the type of functional groups of anionic and cationic polyacrylamide (PAM) and solution pH on the mechanism of polymer adsorption on the surface of dispersed alumina. The polymer-adsorbed amount, surface charge density and zeta potential of solid particles without and with PAM, as well as the stability of Al2O3 suspension containing the polymer, were determined. For this purpose, the spectrophotometry, potentiometric titration, microelectrophoresis and turbidimetry were applied. It was shown that adsorption of anionic PAM decreases with the pH rise, whereas in the case of cationic PAM, it increases. High adsorption level is a result of more coiled structure of adsorbed macromolecules. The anionic PAM has greater impact on the suspension stability deterioration in comparison to the cationic polymer in the whole range of studied pH values. The more pronounced effect of alumina suspension destabilization in the anionic PAM presence was obtained at pH 6, at which solid surface charge neutralization occurs.

For Aqualat filtering material, which is supposed to be used for electroadsorption post-treatment of waters, three methods of zeta-potential determining were applied: streaming potential method, microelectrophoresis and method implemented by Zetatrac analyzer. Besides, the conductive properties of the material were determined in a wide range of electrolyte concentrations .

Fabrication of “cyborg” cells (biological cells with surfaces functionalised using a variety of nanomaterials) has become a fascinating area in cell surface engineering. Here we report a simple procedure for fabrication of polycation-stabilised 50 nm silver nanoparticles and application of these nanoparticles for fabrication of viable “cyborg” microbial cells (yeast and bacteria). Cationic polymer-stabilised nanoparticles electrostatically adhere to microbial cells producing an even monolayer on the cell walls, as demonstrated using enhanced dark-field microscopy, atomic force microscopy and microelectrophoresis. Our procedure is exceptionally fast, being completed within 20 min after introduction of cells into nanoparticle aqueous suspensions. Polymer-stabilised silver nanoparticles are highly biocompatible, with viability rates reaching 97%. We utilised “cyborg” cells built using bacteria and silver nanoparticles to deliver nanoparticles into C. elegans microworms. We believe that the technique described here will find numerous applications in cell surface engineering.