scholarly journals Antimicrobial Coatings from Hybrid Nanoparticles of Biocompatible and Antimicrobial Polymers

2018 ◽  
Vol 19 (10) ◽  
pp. 2965 ◽  
Author(s):  
Carolina Galvão ◽  
Luccas Sanches ◽  
Beatriz Mathiazzi ◽  
Rodrigo Ribeiro ◽  
Denise Petri ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Contact Angles ◽  
Silicon Wafers ◽  
Hybrid Nanoparticles ◽  
Ammonium Bromide ◽  
Antimicrobial Coatings ◽  
Cell Counts ◽  
Conversion Rates ◽  
Nanoparticles Dispersions

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.

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

2019 ◽  
Vol 20 (24) ◽  
pp. 6150 ◽  
Author(s):  
Rodrigo Tadeu Ribeiro ◽  
Carolina Nascimento Galvão ◽  
Yunys Pérez Betancourt ◽  
Beatriz Ideriha Mathiazzi ◽  
Ana Maria Carmona-Ribeiro
Keyword(s):  
Antimicrobial Activity ◽  
Methyl Methacrylate ◽  
Ammonium Chloride ◽  
Silicon Wafers ◽  
Ammonium Bromide ◽  
Microbicidal Activity ◽  
Dimethyl Ammonium Chloride ◽  
Dimethyl Ammonium ◽  
Diallyl Dimethyl Ammonium Chloride

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.

Seed-mediated synthesis and PEG coating of gold nanoparticles for controlling morphology and sizes

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3353-3360
Author(s):  
Susana Helena Arellano Ramírez ◽  
Perla García Casillas ◽  
Christian Chapa González
Keyword(s):  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Room Temperature ◽  
Colloidal Stability ◽  
Infrared Spectrometry ◽  
Ammonium Bromide ◽  
Chloroauric Acid ◽  
Vis Spectroscopy ◽  
Seed Mediated ◽  
Peg Coating

AbstractA significant area of research is biomedical applications of nanoparticles which involves efforts to control the physicochemical properties through simple and scalable processes. Gold nanoparticles have received considerable attention due to their unique properties that they exhibit based on their morphology. Gold nanospheres (AuNSs) and nanorods (AuNRs) were prepared with a seed-mediated method followed of polyethylene glycol (PEG)-coating. The seeds were prepared with 0.1 M cetyltrimethyl-ammonium bromide (CTAB), 0.005 M chloroauric acid (HAuCl4), and 0.01 M sodium borohydride (NaBH4) solution. Gold nanoparticles with spherical morphology was achieved by growth by aggregation at room temperature, while to achieve the rod morphology 0.1 M silver nitrate (AgNO3) and 0.1 M ascorbic acid solution were added. The gold nanoparticles obtained by the seed-mediated synthesis have spherical or rod shapes, depending on the experimental conditions, and a uniform particle size. Surface functionalization was developed using polyethylene glycol. Morphology, and size distribution of AuNPs were evaluated by Field Emission Scanning Electron Microscopy. The average size of AuNSs, and AuNRs was 7.85nm and 7.96 x 31.47nm respectively. Fourier transform infrared spectrometry was performed to corroborate the presence of PEG in the AuNPs surface. Additionally, suspensions of AuNSs and AuNRs were evaluated by UV-Vis spectroscopy. Gold nanoparticles were stored for several days at room temperature and it was observed that the colloidal stability increased once gold nanoparticles were coated with PEG due to the shield formed in the surface of the NPs and the increase in size which were 9.65±1.90 nm of diameter for AuNSs and for AuNRs were 29.03±5.88 and 8.39±1.02 nm for length and transverse axis, respectively.

Direct determination of contact angles of model soils in comparison with wettability characterization by capillary rise

2010 ◽  
Vol 382 (1-4) ◽  
pp. 10-19 ◽  
Author(s):  
Juan Carlos Ramírez-Flores ◽  
Jörg Bachmann ◽  
Abraham Marmur
Keyword(s):  
Capillary Rise ◽  
Direct Determination ◽  
Contact Angles

scholarly journals Development and Validation of Optical Methods for Zeta Potential Determination of Silica and Polystyrene Particles in Aqueous Suspensions

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 290
Author(s):  
Yannic Ramaye ◽  
Marta Dabrio ◽  
Gert Roebben ◽  
Vikram Kestens
Keyword(s):  
Zeta Potential ◽  
Particle Tracking ◽  
Colloidal Stability ◽  
Optical Methods ◽  
Intermediate Precision ◽  
Electrophoretic Light Scattering ◽  
Measurement Uncertainties ◽  
Development And Validation ◽  
Direct Implementation

Zeta potential is frequently used to examine the colloidal stability of particles and macromolecules in liquids. Recently, it has been suggested that zeta potential can also play an important role for grouping and read-across of nanoforms in a regulatory context. Although the measurement of zeta potential is well established, only little information is reported on key metrological principles such as validation and measurement uncertainties. This contribution presents the results of an in-house validation of the commonly used electrophoretic light scattering (ELS) and the relatively new particle tracking analysis (PTA) methods. The performance characteristics were assessed by analyzing silica and polystyrene reference materials. The ELS and PTA methods are robust and have particle mass working ranges of 0.003 mg/kg to 30 g/kg and 0.03 mg/kg to 1.5 mg/kg, respectively. Despite different measurement principles, both methods exhibit similar uncertainties for repeatability (2%), intermediate precision (3%) and trueness (4%). These results confirm that the developed methods can accurately measure the zeta potential of silica and polystyrene particles and can be transferred to other laboratories that analyze similar types of samples. If direct implementation is impossible, the elaborated methodologies may serve as a guide to help laboratories validating their own methods.

Determination of contact angles and pore sizes of porous media by column and thin layer wicking

1992 ◽  
Vol 6 (4) ◽  
pp. 413-428 ◽  
Author(s):  
C.J. Van Oss ◽  
R.F. Giese ◽  
Z. Li ◽  
K. Murphy ◽  
J. Norris ◽  
...  
Keyword(s):  
Porous Media ◽  
Thin Layer ◽  
Contact Angles ◽  
Pore Sizes

Dose determination of nickel implantations in silicon wafers

1991 ◽  
Vol 341 (3-4) ◽  
pp. 245-247 ◽  
Author(s):  
H. Bubert ◽  
P. Burba ◽  
R. Klockenk�mper ◽  
A. Sch�nborn ◽  
M. Wielunski
Keyword(s):  
Silicon Wafers ◽  
Dose Determination ◽  
Determination Of Nickel

scholarly journals Quantitation of mast cell heparin by flow cytofluorometry.

1976 ◽  
Vol 24 (12) ◽  
pp. 1231-1238 ◽  
Author(s):  
L Enerbäck ◽  
G Berlin ◽  
I Svensson ◽  
I Rundquist
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Mixed Cell ◽  
Flow Cytofluorometry ◽  
Frequency Distributions ◽  
Cell Counts ◽  
Mixed Cell Population ◽  
Number Of Cells ◽  
Excellent Reproducibility

Mast cells can be automatically identified in a mixed cell population by flow cytofluorometry after Berberine sulphate staining. Volume specific counts of the total number of cells and number of mast cells, as well as frequency distributions of fluorescence intensities of mast cells, based on a large number of cells, can be rapidly obtained. Results obtained by microscope fluorometry of cells identified by phase contrast microscopy showviously published results it may be inferred that the fluorescence intensity of individual mast cells is proportional to mast cell heparin content. The automated cell counts correlated very well with manual hemocytometer counts. Both cell counts and the determination of mean mast cell fluorescence showed excellent reproducibility.

Sign in / Sign up

Export Citation Format

Share Document