Antimicrobial particles from emulsion polymerization of methyl methacrylate in the presence of quaternary ammonium surfactants

Antibacterial and antifungal action of CTAB-containing silica nanoparticles against human pathogens

New antibiotic agents are urgently needed worldwide to combat the increasing tolerance and resistance of pathogenic fungi and bacteria to current antimicrobials. Here, we looked at the antibacterial and antifungal effects of minor quantities of cetyltrimethylammonium bromide (CTAB), ca. 93.8 mg g^-1, on silica nanoparticles (MPSi-CTAB). Our results show that MPSi-CTAB exhibits antimicrobial activity against Methicillin-resistant Staphylococcus aureus strain (S. aureus ATCC 700698) with MIC and MBC of 0.625 mg mL^-1 and 1.25 mg mL^-1, respectively. Additionally, for Staphylococcus epidermidis ATCC 35984, MPSi-CTAB reduces MIC and MBC by 99.99% of viable cells on the biofilm. Furthermore, when combined with ampicillin or tetracycline, MPSi-CTAB exhibits reduced MIC values by 32- and 16-folds, respectively. MPSi-CTAB also exhibited in vitro antifungal activity against reference strains of Candida, with MIC values ranging from 0.0625 to 0.5 mg mL^-1. This nanomaterial has low cytotoxicity in human fibroblasts, where over 80% of cells remained viable at 0.31 mg mL^-1 of MPSi-CTAB. Finally, we developed a gel formulation of MPSi-CTAB, which inhibited in vitro the growth of Staphylococcus and Candida strains. Overall, these results support the efficacy of MPSi-CTAB with potential application in the treatment and/or prevention of infections caused by methicillin-resistant Staphylococcus and/or Candida species.

Bacterial Response to the Surface Aging of PLA Matrices Loaded with Active Compounds

The use of active components in biomaterials improves the properties of existing ones and makes it possible to obtain new devices with antibacterial properties that prevent infections after implantation, thus guaranteeing the success of the implant. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles were incorporated into polylactic acid (PLA) films to assess the extent to which progressive aging of the new surfaces resists bacterial colonization processes. For this purpose, the films' surface was characterized by contact angle measurements, ToF-SIMS and AFM, and adhesion, viability and biofilm growth of Staphylococcus epidermidis bacteria on these films were also evaluated. The results show that the inclusion of Mg and CTAB in PLA films changes their surface properties both before and after aging and also modifies bacterial adhesion on the polymer. Complete bactericidal activity is exhibited on non-degraded films and films with CTAB. This antibacterial behavior is maintained after degradation for three months in the case of films containing a higher amount of CTAB.

Cationic Nanostructures as Adjuvants for Vaccines

Spherical or discoidal lipid polymer nanostructures bearing cationic charges successfully adsorb a variety of oppositely charged antigens (Ag) such as proteins, peptides, nucleic acids, or oligonucleotides. This report provides instructions for the preparation and physical characterization of four different cationic nanostructures able to combine and deliver antigens to the immune system: (1) dioctadecyl dimethylammonium bromide (DODAB) bilayer fragments (DODAB BF); (2) polystyrene sulfate (PSS) nanoparticles (NPs) covered with one cationic dioctadecyl dimethylammonium bromide bilayer (DODAB) named (PSS/DODAB); (3) cationic NPs of biocompatible polymer poly(methyl methacrylate) (PMMA) prepared by emulsion polymerization of the methyl methacrylate (MMA) monomer in the presence of DODAB BF (PMMA/DODAB NPs); (4) antigen NPs (NPs) where the cationic polymer poly(diallyl dimethyl ammonium chloride) (PDDA) directly combined at nontoxic and low dose with the antigen (Ag); when the oppositely charged model antigen is ovalbumin (OVA), NPs are named PDDA/OVA. These nanostructures provide adequate microenvironments for carrying and delivering antigens to the antigen-presenting cells of the immune system.

Supramolecular Nanostructures for Vaccines

Although this is an era of pandemics and many devastating diseases, this is also a time when bionanotechnology flourishes, illuminating a multidisciplinary field where vaccines are quickly becoming a balsam and a prevention against insidious plagues. In this work, we tried to gain and also give a deeper understanding on nanovaccines and their way of acting to prevent or cure cancer, infectious diseases, and diseases caused by parasites. Major nanoadjuvants and nanovaccines are temptatively exemplified trying to contextualize our own work and its relative importance to the field. The main properties for novel adjuvants seem to be the nanosize, the cationic character, and the biocompatibility, even if it is achieved in a low dose-dependent manner.

Cationic and Biocompatible Polymer/Lipid Nanoparticles as Immunoadjuvants

Nanostructures have been of paramount importance for developing immunoadjuvants. They must be cationic and non-cytotoxic, easily assembling with usually oppositely charged antigens such as proteins, haptens or nucleic acids for use in vaccines. We obtained optimal hybrid nanoparticles (NPs) from the biocompatible polymer poly(methyl methacrylate) (PMMA) and the cationic lipid dioctadecyl dimethyl ammonium bromide (DODAB) by emulsion polymerization of methyl methacrylate (MMA) in the presence of DODAB. NPs adsorbed ovalbumin (OVA) as a model antigen and we determined their adjuvant properties. Interestingly, they elicited high double immune responses of the cellular and humoral types overcoming the poor biocompatibility of DODAB-based adjuvants of the bilayer type. The results suggested that the novel adjuvant would be possibly of use in a variety of vaccines.

Biomimetic Lipid Polymer Nanoparticles for Drug Delivery

Biomimetic nanoparticles are hybrid nanostructures in which the uppermost layer is similar to a cell membrane. In these nanoparticles, lipids and biopolymers can be organized to improve drug incorporation and delivery. This report provides instructions for the preparation and physical characterization of four different biomimetic nanoparticles: (1) polystyrene sulphate (PSS) nanoparticles covered with one cationic dioctadecyl dimethylammonium bromide bilayer (DODAB), which incorporates dimeric channels of the antimicrobial peptide Gramicidin D; (2) silica nanoparticles covered with one single bilayer of the antimicrobial cationic lipid DODAB; (3) hybrid lipid/polymer indomethacin (IND) nanoparticles from injection of IND/DODAB ethanolic solution in a water solution of carboxymethyl cellulose (CMC); (4) bactericidal and fungicidal nanoparticles from DODAB bilayer fragments (BF) covered consecutively by a CMC and a poly(diallyl dimethyl ammonium chloride) (PDDA) layer. These examples provide the basis for the preparation and characterization of novel biomimetic nanoparticles with lipids and/or biopolymers in their composition. The polymers and lipids in the hybrid nanoparticle composition may impart stability and/or bioactivity and/or provide adequate microenvironments for carrying bioactive drugs and biomolecules.

Biocompatible Lipid Polymer Cationic Nanoparticles for Antigen Presentation

Biocompatible lipid polymer nanoparticles (NPs) previously used as antimicrobial agents are explored here as immuno-adjuvants. Poly (methyl methacrylate) (PMMA)/dioctadecyldimethylammonium bromide (DODAB)/poly (diallyldimethylammonium chloride) (PDDA) nanoparticles (NPs) were prepared by emulsion polymerization of methyl methacrylate (MMA) in the presence of DODAB and PDDA, with azobisisobutyronitrile (AIBN) as the initiator. NPs characterization after dialysis by dynamic light-scattering yielded 225 ± 2 nm hydrodynamic diameter (Dz), 73 ± 1 mV zeta-potential (ζ), and 0.10 ± 0.01 polydispersity (P). Ovalbumin (OVA) adsorption reduced ζ to 45 ± 2 mV. Balb/c mice immunized with NPs/OVA produced enhanced OVA-specific IgG1 and IgG2a, exhibited moderate delayed type hypersensitivity reaction, and enhanced cytokines production (IL-4, IL-10, IL-2, IFN-γ) by cultured spleen cells. There was no cytotoxicity against cultured macrophages and fibroblasts. Advantages of the PMMA/DODAB/PDDA NPs were high biocompatibility, zeta-potential, colloidal stability, and antigen adsorption. Both humoral and cellular antigen-specific immune responses were obtained.

Cationic Nanostructures for Vaccines Design

Subunit vaccines rely on adjuvants carrying one or a few molecular antigens from the pathogen in order to guarantee an improved immune response. However, to be effective, the vaccine formulation usually consists of several components: an antigen carrier, the antigen, a stimulator of cellular immunity such as a Toll-like Receptors (TLRs) ligand, and a stimulator of humoral response such as an inflammasome activator. Most antigens are negatively charged and combine well with oppositely charged adjuvants. This explains the paramount importance of studying a variety of cationic supramolecular assemblies aiming at the optimal activity in vivo associated with adjuvant simplicity, positive charge, nanometric size, and colloidal stability. In this review, we discuss the use of several antigen/adjuvant cationic combinations. The discussion involves antigen assembled to 1) cationic lipids, 2) cationic polymers, 3) cationic lipid/polymer nanostructures, and 4) cationic polymer/biocompatible polymer nanostructures. Some of these cationic assemblies revealed good yet poorly explored perspectives as general adjuvants for vaccine design.

Hybrid Nanoparticles of Poly (Methyl Methacrylate) and Antimicrobial Quaternary Ammonium Surfactants

Quaternary ammonium surfactants (QACs) are microbicides, whereas poly (acrylates) are biocompatible polymers. Here, the physical and antimicrobial properties of two QACs, cetyl trimethyl ammonium bromide (CTAB) or dioctadecyl dimethyl ammonium bromide (DODAB) in poly (methyl methacrylate) (PMMA) nanoparticles (NPs) are compared to those of QACs alone. Methyl methacrylate (MMA) polymerization using DODAB or CTAB as emulsifiers and initiator azobisisobutyronitrile (AIBN) yielded cationic, nanometric, homodisperse, and stable NPs. NPs’ physical and antimicrobial properties were assessed from dynamic light scattering (DLS), scanning electron microscopy, and viability curves of Escherichia coli, Staphylococcus aureus, or Candida albicans determined as log(colony-forming unities counting) over a range of [QACs]. NPs were spherical and homodisperse but activity for free QACs was higher than those for QACs in NPs. Inhibition halos against bacteria and yeast were observed only for free or incorporated CTAB in NPs because PMMA/CTAB NPs controlled the CTAB release. DODAB displayed fungicidal activity against C. albicans since DODAB bilayer disks could penetrate the outer glycoproteins fungus layer. The physical properties and stability of the cationic NPs highlighted their potential to combine with other bioactive molecules for further applications in drug and vaccine delivery.

Polymeric and inorganic nanoscopical antimicrobial fillers in dentistry

Failure of dental treatments is mainly due to the biofilm accumulated on the dental materials. Many investigations have been conducted on the advancements of antimicrobial dental materials. Polymeric and inorganic nanoscopical agents are capable of inhibiting microorganism proliferation. Applying them as fillers in dental materials can achieve enhanced microbicidal ability. The present review provides a broad overview on the state-of-the-art research in the field of antimicrobial fillers which have been adopted for incorporation into dental materials over the last 5 years. The antibacterial agents and applications are described, with the aim of providing information for future investigations. STATEMENT OF SIGNIFICANCE: Microbial infection is the primary cause of dental treatment failure. The present review provides an overview on the state-of-art in the field of antimicrobial nanoscopical or polymeric fillers that have been applied in dental materials. Trends in the biotechnological development of these antimicrobial fillers over the last 5 years are reviewed to provide a backdrop for further advancement in this field of research.

Microbicidal Dispersions and Coatings from Hybrid Nanoparticles of Poly (Methyl Methacrylate), Poly (Diallyl Dimethyl Ammonium) Chloride, Lipids, and Surfactants

Hybrid and antimicrobial nanoparticles (NPs) of poly (methyl methacrylate) (PMMA) in the presence of poly (diallyl dimethyl ammonium) chloride (PDDA) were previously obtained by emulsion polymerization in absence of surfactant with low conversion. In the presence of amphiphiles such as cetyl trimethyl ammonium bromide (CTAB), dioctadecyl dimethyl ammonium bromide (DODAB) or soybean lecithin, we found that conversion increased substantially. In this work, the effect of the amphiphiles on the NPs core-shell structure and on the antimicrobial activity of the NPs was evaluated. NPs dispersions casted on silicon wafers, glass coverslips or polystyrene substrates were also used to obtain antimicrobial coatings. Methods for characterizing the dispersions and coatings were based on scanning electron microscopy, dynamic light scattering, determination of thickness, rugosity, and wettability for the coatings and determination of colony-forming unities (log CFU/mL) of microbia after 1 h interaction with the coatings or dispersions. The amphiphiles used during PMMA/PDDA/amphiphile NPs synthesis reduced the thickness of the NPs PDDA shell surrounding each particle. The antimicrobial activity of the dispersions and coatings were due to PDDA-the amphiphiles were either washed out by dialysis or remained in the PMMA polymeric core of the NPs. The most active NPs and coatings were those of PMMA/PDDA/CTAB-the corresponding coatings showed the highest rugosity and total surface area to interact with the microbes. The dispersions and coatings obtained by casting of the NPs dispersions onto silicon wafers were hydrophilic and exhibited microbicidal activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. In addition, a major effect of reduction in particle size revealed the suitability of nanometric and cationic NPs (sizes below 100 nm) represented by PMMA/PDDA/CTAB NPs to yield maximal microbicidal activity from films and dispersions against all microbia tested. The reduction of cell viability by coatings and dispersions amounted to 6-8 logs from [PDDA] ≥ minimal microbicidal concentration.

Takes Two to Tango: Choreography of the Coadsorption of CTAB and Hexanol at the Oil-Water Interface

Mixed surfactant systems at the oil-water interface play a vital role in applications ranging widely from drug delivery to oil-spill remediation. Synergistic mixtures are superior emulsifiers and more effective at modifying surface tension than either component alone. Mixtures of surfactants with dissimilar polar head groups are of particular interest because of the additional degree of control they offer. The interplay of hydrophobic and electrostatic effects in these systems is not well understood, in part because of the difficulty in examining their behavior at the buried oil-water interface where they reside. Here, surface-specific vibrational sum frequency spectroscopy is utilized in combination with surface tensiometry and computational methods to probe the cooperative molecular interactions between a cationic surfactant cetyltrimethylammonium bromide (CTAB) and a nonionic alcohol (1-hexanol) that induce the two initially reluctant surfactants to coadsorb synergistically at the interface. A careful deuteration study of CTAB reveals that hexanol cooperates with CTAB such that both molecules preferentially orient at the interface for sufficiently large enough concentrations of hexanol. This work's methodology is unique and serves as a guide for future explorations of macroscopic properties in these complex systems. Results from this work also provide valuable insights into how interfacial ordering impacts surface tensiometry measurements for nonionic surfactants.

Preparation and Evaluation of Antimicrobial Hyperbranched Emulsifiers for Waterborne Coatings

Nosocomial infections are a major problem in medical health care. To solve this problem, a series of antimicrobial waterborne paints were prepared by using antimicrobial hyperbranched (HB) emulsifiers. The HB-emulsifiers were prepared by polymerizing AB₂ monomers obtained in a one-step reaction of bis(hexamethylene)triamine and carbonyl biscaprolactam. The blocked isocyanate end groups (B groups) of the HB-polymer were utilized to introduce tertiary amino groups through the reaction with compounds comprising either a hydroxyl or a primary amino group and a tertiary amino group. Quaternization of the tertiary amines with 6 different alkyl bromides resulted in 12 amphiphilic cationic species. The 12 emulsifiers showed the successful inhibition and killing of 8 bacterial and 2 fungal strains. The killing efficacy increased with increasing alkyl chain length. The octyl-functionalized compound was chosen for suspension polymerizations because of the good compromise between killing and emulsifying properties. With this emulsifier, aqueous poly(methacrylate) suspensions were prepared, which were stable and had excellent killing properties.

Colloidal Stability of Positively Charged Dispersions of Styrene and Acrylic Copolymers in the Presence of TiO2 and CaCO3

Increasing antibiotic resistance of several pathogenic microorganisms calls for alternative approaches to prevent spreading of bacterial diseases. We propose to employ for this purpose coatings obtained from positively charged latex dispersions. In this contribution we characterize aqueous mixed dispersions containing TiO2 or CaCO3 and methyl methacrylate-ethyl acrylate or styrene-ethyl acrylate copolymers synthesized using a cationic surfactant, cetyltrimethylammonium bromide as an emulsifier. Particle size, electrokinetic (ζ) potential of the mixed dispersions and the resulting thin films, as well as antimicrobial properties of the latter are described. The TiO2 and CaCO3 dispersions were stabilised with polyethyleneimine (PEI) and optimum pH for the mixed dispersions were chosen on the basis of ζ-potential measurements. For TiO2, the maximum ζ = +35 mV was found at pH 7.5, and for CaCO3, pH was set at 8.2 (ζ = +38 mV), to prevent its dissolution. In most 1:1 mixtures of TiO2 or CaCO3 with the cetyltrimethylammonium bromide (CTAB)-stabilised latex dispersions, two distinct particles populations were observed, corresponding to the bare latex and bare TiO2 or CaCO3 fractions. Films made of the mixed dispersions remained positively charged and showed antimicrobial activity similar or reduced with respect to the bare polymer films.

Antimicrobial Coatings from Hybrid Nanoparticles of Biocompatible and Antimicrobial Polymers

Hybrid nanoparticles of poly(methylmethacrylate) synthesized in the presence of poly (diallyldimethyl ammonium) chloride by emulsion polymerization exhibited good colloidal stability, physical properties, and antimicrobial activity but their synthesis yielded poor conversion. Here we create antimicrobial coatings from casting and drying of the nanoparticles dispersions onto model surfaces such as those of silicon wafers, glass coverslips, or polystyrene sheets and optimize conversion using additional stabilizers such as cetyltrimethyl ammonium bromide, dioctadecyldimethyl ammonium bromide, or soybean lecithin during nanoparticles synthesis. Methodology included dynamic light scattering, determination of wettability, ellipsometry of spin-coated films, scanning electron microscopy, and determination of colony forming unities (log CFU/mL) of bacteria after 1 h interaction with the coatings. The additional lipids and surfactants indeed improved nanoparticle synthesis, substantially increasing the conversion rates by stabilizing the monomer droplets in dispersion during the polymerization. The coatings obtained by spin-coating or casting of the nanoparticles dispersions onto silicon wafers were hydrophilic with contact angles increasing with the amount of the cationic polymer in the nanoparticles. Against Escherichia coli and Staphylococcus aureus, bacteria cell counts were reduced by approximately 7 logs upon interaction with the coatings, revealing their potential for several biotechnological and biomedical applications.

Self-Assembled Antimicrobial Nanomaterials

Nanotechnology came to stay improving the quality of human life by reducing environmental contamination of earth and water with pathogens. This review discusses how self-assembled antimicrobial nanomaterials can contribute to maintain humans, their water and their environment inside safe boundaries to human life even though some of these nanomaterials display an overt toxicity. At the core of their strategic use, the self-assembled antimicrobial nanomaterials exhibit optimal and biomimetic organization leading to activity at low doses of their toxic components. Antimicrobial bilayer fragments, bilayer-covered or multilayered nanoparticles, functionalized inorganic or organic polymeric materials, coatings and hydrogels disclose their potential for environmental and public health applications in this review.

Zeta Potential of Poly(methyl methacrylate) (PMMA) in Contact with Aqueous Electrolyte-Surfactant Solutions

The addition of surfactants can considerably impact the electrical characteristics of an interface, and the zeta potential measurement is the standard method for its characterization. In this article, a comprehensive study of the zeta potential of poly(methyl methacrylate) (PMMA) in contact with aqueous solutions containing an anionic, a cationic, or a zwitterionic surfactant at different pH and ionic strength values is conducted. Electrophoretic mobilities are inferred from electrophoretic light scattering measurements of the particulate PMMA. These values can be converted into zeta potentials using permittivity and viscosity measurements of the continuous phase. Different behaviors are observed for each surfactant type, which can be explained with the various adsorption mechanisms on PMMA. For the anionic surfactant, the absolute zeta potential value below the critical micelle concentration (CMC) increases with the concentration, while it becomes rather constant around the CMC. At concentrations above the CMC, the absolute zeta potential increases again. We propose that hydrophobic-based adsorption and, at higher concentrations, the competing micellization process drive this behavior. The addition of cationic surfactant results in an isoelectric point below the CMC where the negative surface charge is neutralized by a layer of adsorbed cationic surfactant. At concentrations near the CMC, the positive zeta potential is rather constant. In this case, we propose that electrostatic interactions combined with hydrophobic adsorption are responsible for the observed behavior. The zeta potential in the presence of zwitterionic surfactant is influenced by the adsorption, because of hydrophobic interactions between the surfactant tail and the PMMA surface. However, there is less influence, compared to the ionic surfactants. For all three surfactant types, the zeta potential changes to more-negative or less-positive values for alkaline pH values, because of hydroxide adsorption. An increase of the ionic strength decreases the absolute value of the zeta potential, because of the shielding effects.

Antibacterial Adhesion of Poly(methyl methacrylate) Modified by Borneol Acrylate

Poly(methyl methacrylate) (PMMA) is a widely used biomaterial. But there is still a challenge facing its unwanted bacterial adhesion because the subsequent biofilm formation usually leads to failure of related implants. Herein, we present a borneol-modified PMMA based on a facile and effective stereochemical strategy, generating antibacterial copolymer named as P(MMA-co-BA). It was synthesized by free radical polymerization and studied with different ratio between methyl methacrylate (MMA) and borneol acrylate (BA) monomers. NMR, GPC, and EA, etc., were used to confirm their chemical features. Their films were challenged with Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive), showing a BA content dependent antibacterial performance. The minimum effective dose should be 10%. Then in vivo subcutaneous implantations in mice demonstrated their biocompatibilities through routine histotomy and HE staining. Therefore, P(MMA-co-BA)s not only exhibited their unique antibacterial character but also suggested a potential for the safe usage of borneol-modified PMMA frame and devices for further implantation.

Cationic amphiphile in phospholipid bilayer or oil-water interface of nanocarriers affects planktonic and biofilm bacteria killing

A cationic amphiphile, soyaethyl morpholinium ethosulfate (SME), immobilized in liposomes or nanoemulsions, was prepared in an attempt to compare the antibacterial activity between SME intercalated in the phospholipid bilayer and oil-water interface. Before antibacterial assessment, the size of the liposomes and nanoemulsions was respectively recorded as 75 and 214 nm. The data of minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) and live/dead cell count demonstrated a superior antimicrobial activity of nanoemulsions compared to liposomes against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and Staphylococcus epidermidis. Nanoemulsion incubation reduced biofilm thickness by 2.4-fold, whereas liposomes showed a 1.6-fold decrease in thickness. SME insertion in the oil-water phase was found to induce bacterial membrane disruption. SME nanosystems were nontoxic to keratinocytes. In vivo topical application of the cationic nanosystems reduced skin infection, MRSA load, and inflammation in mice. The deteriorated skin barrier function evoked by MRSA was recovered by nanoemulsion treatment.

Synthesis and characterization of crosslinked polyisothiouronium methylstyrene nanoparticles of narrow size distribution for antibacterial and antibiofilm applications

Background

Isothiouronium salts are well known in their variety of antimicrobials activities. The use of polymeric biocides, polymers with antimicrobial activities, is expected to enhance the efficacy of some existing antimicrobial agents, thus minimizing the environmental problems accompanying conventional antimicrobials.

Methods

The current manuscript describes the synthesis and characterization of crosslinked polyisothiouronium methylstyrene (PITMS) nanoparticles (NPs) of narrow size distribution by dispersion co-polymerization of the monomer isothiouronium methylstyrene with the crosslinking monomer ethylene glycol dimetacrylate.

Results and discussion

The effect of total monomer, crosslinker and initiator concentrations on the size and size distribution of the formed NPs was also elucidated. The bactericidal activity of PITMS NPs of 67 ± 8 nm diameter was illustrated for 4 bacterial pathogens: Listeria innocua, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. In order to demonstrate the potential of these PITMS NPs as inhibitor of biofilm formation, polyethylene terephthalate (PET) films were thin-coated with the PITMS NPs. The formed PET/PITMS films reduced the viability of the biofilm of Listeria by 2 orders of magnitude, making the coatings excellent candidates for further development of non-fouling surfaces. In addition, PITMS NP coatings were found to be non-toxic in HaCaT cells.

Conclusions

The high antibacterial activity and effective inhibition of bacterial adsorption indicate the potential of these nanoparticles for development of new types of antibacterial and antibiofilm additives.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-016-0208-7) contains supplementary material, which is available to authorized users.

The antimicrobial activity of free and immobilized poly (diallyldimethylammonium) chloride in nanoparticles of poly (methylmethacrylate)

Background

Several cationic polymers exhibit a useful antimicrobial property, however the structure–activity relationship still requires a more complete investigation. The main objective of this work is the comparison between the antimicrobial activity and toxicity of free and immobilized poly (diallyldimethylammonium) chloride (PDDA) in biocompatible poly (methylmethacrylate) (PMMA) nanoparticles (NPs).

Results

NPs synthesis by emulsion polymerization is performed over a range of [PDDA] at two methylmethacrylate (MMA) concentrations. The PMMA/PDDA dispersions are characterized by dynamic light-scattering for sizing, polydispersity and zeta-potential analysis, scanning electron microscopy (SEM), plating plus colony forming unities (CFU) counting for determination of the minimal microbicidal concentrations (MMC) against Escherichia coli, Staphylococcus aureus and Candida albicans and hemolysis evaluation against mammalian erythrocytes. There is a high colloidal stability for the cationic PMMA/PDDA NPs over a range of [PDDA]. NPs diverse antimicrobial activity against the microorganisms reduces cell viability by eight-logs (E. coli), seven-logs (S. aureus) or two-logs (C. albicans). The NPs completely kill E. coli over a range of [PDDA] that are innocuous to the erythrocytes. Free PDDA antimicrobial activity is higher than the one observed for PDDA in the NPs. There is no PDDA induced-hemolysis at the MMC in contrast to the hemolytic effect of immobilized PDDA in the NPs. Hemolysis is higher than 15 % for immobilized PDDA at the MMC for S. aureus and C. albicans.

Conclusions

The mobility of the cationic antimicrobial polymer PDDA determines its access to the inner layers of the cell wall and the cell membrane, the major sites of PDDA antimicrobial action. PDDA freedom does matter for determining the antimicrobial activity at low PDDA concentrations and absence of hemolysis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0123-3) contains supplementary material, which is available to authorized users.

Supramolecular cationic assemblies against multidrug-resistant microorganisms: activity and mechanism of action

The growing challenge of antimicrobial resistance to antibiotics requires novel synthetic drugs or new formulations for old drugs. Here, cationic nanostructured particles (NPs) self-assembled from cationic bilayer fragments and polyelectrolytes are tested against four multidrug-resistant (MDR) strains of clinical importance. The non-hemolytic poly(diallyldimethylammonium) chloride (PDDA) polymer as the outer NP layer shows a remarkable activity against these organisms. The mechanism of cell death involves bacterial membrane lysis as determined from the leakage of inner phosphorylated compounds and possibly disassembly of the NP with the appearance of multilayered fibers made of the NP components and the biopolymers withdrawn from the cell wall. The NPs display broad-spectrum activity against MDR microorganisms, including Gram-negative and Gram-positive bacteria and yeast.

Water-based synthesis of cationic hydrogel particles: effect of the reaction parameters and in vitro cytotoxicity study

Simple variation of reaction parameters can provide a library of cationic epoxy–amine hydrogel particles with a diverse collection of physical and chemical characteristics, temperature responsiveness, and cytocompatibility.

Functional surfaces obtained from emulsion polymerization using antimicrobial glycosylated block copolymers as surfactants

Antimicrobial surfaces were obtained from latex particles stabilized with amphiphilic block copolymer surfactants containing both quaternary ammonium and carbohydrate groups.

Synthesis and properties of quaternary ammonium surfactants containing a methoxy benzyl substitute

m-MDRA-n exhibit high surface activity, excellent adsorptive and bacterial properties, thermodynamic functions of micellization for m-MDRA-n were researched.