Polystyrene Latex Nanoparticles Research Articles

Rapid and facile detection of PBTC antiscalant using functionalized polystyrene nanoparticles and latex agglutination

Organophosphate-based compounds, particularly 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), have been crucial in circulating cooling systems and wastewater treatments as corrosion inhibitors preventing scale deposits in industrial facilities. Employing the reagent within its optimum concentration range is essential for effective performance, minimizing costs and environmental impacts. However, measuring PBTC separately can be challenging due to its functional groups’ similarity to other common molecules found in natural water, necessitating complex procedures. In this study, amine-functionalized polystyrene (PS) latex nanoparticles were synthesized through emulsifier-free emulsion polymerization and utilized as nanosorbents for PBTC detection via a straightforward latex agglutination method. This phenomenon is facilitated by electrostatic and hydrogen bonding interactions between the positively charged layers on the particle’s surface and the negatively charged PBTC molecules. The pH and concentration of the PBTC solution are key factors influencing the adsorption behavior and capacity of the functionalized latex particles. A graphical representation of aggregation domains, dependent on both PBTC concentration and pH, was created. This map serves as an effective tool for detecting PBTC concentration. The resulting particles show great promise for monitoring the concentration range of phosphate additives in water, offering a simple, rapid detection process with low costs and reduced chemical and equipment requirements.

The Development of an AF4 Characterization Pipeline for Polymeric Nanoparicle-Protein Interactions

The centrifugation-wash method is currently the standard technique used for the recovery of nanoparticle-protein complexes from protein-containing serum. However, this technique is disruptive, and leads to changes in nanoparticle parameters and the surface-bound protein composition. In this study, we explore the use of field flow fractionation (FFF) for the development of a robust pipeline for the characterization of nanoparticle parameters following protein corona formation under physiologically-relevant conditions. Model surface-modified polystyrene latex nanoparticles were treated with protein-containing medium mimicking cell-culture conditions under physiologically-relevant conditions. Following incubation, nanoparticle-protein samples were then fractionated using the FFF system and characterized using in-line detectors. Conventional nanoparticle-protein studies typically use the highly invasive centrifugation-wash method which leads to changes in measured particle parameters. Our studies show that AF4 allows for high resolution and characterization of in-situ nanoparticle-protein complexes. This work will allow for the development of a more harmonized approach for characterizing nanoparticle-protein interactions under biologically-relevant conditions.

Comprehensive Comparison of the Capacity of Functionalized Sepharose, Magnetic Core, and Polystyrene Nanoparticles to Immuno-Precipitate Procalcitonin from Human Material for the Subsequent Quantification by LC-MS/MS

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. The fast and accurate diagnosis of sepsis by procalcitonin (PCT) has emerged as an essential tool in clinical medicine. Although in use in the clinical laboratory for a long time, PCT quantification has not yet been standardized. The International Federation of Clinical Chemistry working group on the standardization of PCT (IFCC-WG PCT) aims to provide an LC-MS/MS-based reference method as well as the highest metrological order reference material to address this diagnostic need. Here, we present the systematic evaluation of the efficiency of an immuno-enrichment method, based on functionalized Sepharose, magnetic-core, or polystyrene (latex) nano-particles, to quantitatively precipitate PCT from different human sample materials. This method may be utilized for both mass spectrometric and proteomic purposes. In summary, only magnetic-core nano-particles functionalized by polyclonal PCT antibodies can fulfil the necessary requirements of the international standardization of PCT. An optimized method proved significant benefits in quantitative and specific precipitation as well as in the subsequent LC-MS/MS detection of PCT in human serum samples or HeLa cell extract. Based on this finding, further attempts of the PCT standardization process will utilize a magnetic core-derived immuno-enrichment step, combined with subsequent quantitative LC-MS/MS detection.

Dual functionality of ferrocene-based metallopolymers as radical scavengers and nanoparticle stabilizing agents.

The beneficial redox properties of ferrocene-based polymers have been utilized during in situ preparation of metallic nanoparticles, while such redox features also indicate a great promise in applications as free radical scavengers. Here, colloidal dispersions of an antioxidant nanozyme composed of amidine-functionalized polystyrene latex (AL) nanoparticles, negatively charged poly(ferrocenylsilane) (PFS(-)) organometallic polyions, and ascorbic acid (AA) were formulated. The AL was first functionalized with PFS(-). Increasing the polymer dose resulted in charge neutralization and subsequent charge reversal of the particles. The strength of repulsive interparticle forces of electrostatic nature was significant at low and high doses leading to stable colloids, while attractive forces dominated near the charge neutralization point giving rise to unstable dispersions. The saturated PFS(-) layer adsorbed on the surface of the AL (p-AL nanozyme) enhanced the colloidal stability against salt-induced aggregation without affecting the pH-dependent charge and size of the particles. The joint effect of PFS(-) and the AA in radical decomposition was observed indicating the antioxidant potential of the system. The immobilization of PFS(-) deteriorated its scavenging activity, yet the combination with AA improved this feature. The results indicate that p-AL-AA is a promising radical scavenger since the high colloidal stability of the particles allows application in heterogeneous systems, such as in industrial manufacturing processes, where antioxidants are required to maintain acceptable product quality.

Optical-field-induced surface nanobumps in near-infrared laser direct cleaning of nanoparticles on silicon.

The evolution of surface damage in laser direct cleaning (LDC) of nanoparticulate contamination on silicon (Si) was theoretically and experimentally investigated. Nanobumps with a volcano-like shape were found in near-infrared laser cleaning of polystyrene latex nanoparticles on Si wafers. According to the finite-difference time-domain simulation and the high-resolution surface characterization, unusual particle-induced optical field enhancement in the vicinity of the interface between Si and nanoparticles is mainly responsible for the generation of volcano-like nanobumps. This work is of fundamental significance for the understanding of the laser-particle interaction during LDC and will promote the development of nanofabrication and nanoparticle cleaning applications in optics, microelectromechanical systems, and semiconductors.

Retention and Fouling during Nanoparticle Filtration: Implications for Membrane Purification of Biotherapeutics.

One major challenge in the development of nanoparticle-based therapeutics, including viral vectors for the delivery of gene therapies, is the development of cost-effective purification technologies. The objective of this study was to examine fouling and retention behaviors during the filtration of model nanoparticles through membranes of different pore sizes and the effect of solution conditions. Data were obtained with 30 nm fluorescently labeled polystyrene latex nanoparticles using both cellulosic and polyethersulfone membranes at a constant filtrate flux, and both pressure and nanoparticle transmission were evaluated as a function of cumulative filtrate volume. The addition of NaCl caused a delay in nanoparticle transmission and an increase in fouling. Nanoparticle transmission was also a function of particle hydrophobicity. These results provide important insights into the factors controlling transmission and fouling during nanoparticle filtration as well as a framework for the development of membrane processes for the purification of nanoparticle-based therapeutics.

Blind-zone formation in laser shockwave nano-cleaning.

Laser shockwave cleaning (LSC) has attracted growing attention due to its advantages in non-contact, site-selective nanoparticle removal on microelectronic/optical devices. However, an uncleaned blind-zone formed directly under the laser-induced plasma kernel severely affects the cleaning effect. Laser shockwave cleaning of 300 nm polystyrene latex nanoparticles on silicon wafers is fully explored to understand the blind-zone formation mechanism. The size of the uncleaned blind-zone quickly increases from 0.84 to 19.50 mm2 associated with a growing fraction of the uncleaned blind-zone area within the whole cleaned area from 0.05 to 0.93 as the plasma-substrate gap distance is increased from 0.5 to 2 mm and the laser fluence is increased from 75 to 150 J/cm2. Besides, the variation of the blind-zone size is more strongly dependent on the plasma-substrate gap distance than the laser fluence. A time-resolved analysis of the laser-induced plasma evolution shows an inseparable relationship between the blind-zone and the geometric location of the plasma kernel. Theoretical analysis of the removal force in LSC based on the rolling mode reveals that the lack of dragging force acting on the nanoparticles in the region right under the plasma kernel impedes their removal and causes the uncleaned blind-zone formation.

The Toxicity of Polystyrene-Based Nanoparticles in Saccharomyces cerevisiae Is Associated with Nanoparticle Charge and Uptake Mechanism.

Polystyrene latex (PSL) nanoparticles (NPs), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes, and hybrid NPs that have different concentrations, sizes, surface charges, and functional groups were used to determine their toxicity to Saccharomyces cerevisiae cells. The size, charge, and morphology of the nanoparticles were characterized by dynamic light scattering, electrophoretic light scattering, scanning transmission electron microscopy, and transmission electron microscopy analysis. The cell viabilities were determined by colony forming unit analysis and confocal laser scanning microscopy imaging. Uptake inhibition studies were performed to determine the internalization mechanism of PSL NPs. At 50 mg/L, both positively and negatively charged NPs were slightly toxic. With increasing concentration, however, full toxicities were observed with positively charged PSL NPs, while a marginal increase in toxicity was obtained with negatively charged PSL NPs. For negatively charged and carboxyl-functionalized NPs, an increase in size induced toxicity, whereas for positively charged and amine-functionalized NPs, smaller-sized NPs were more toxic to yeast cells. Negatively charged NPs were internalized by the yeast cells, but they showed toxicity when they entered the cell vacuole. Positively charged NPs, however, accumulated on the cell surface and caused toxicity. When coated with DOPC liposomes, positively charged NPs became significantly less toxic. We attribute this reduction to the larger-diameter and/or more-agglomerated NPs in the extracellular environment, which resulted in lower interactions with the cell. In addition to endocytosis, it is possible that the negatively charged NPs (30-C-n) were internalized by the cells, partly via direct permeation, which is preferred for high drug delivery efficiency. Negatively charged PSL NP exposure to the yeast cells at low-to-moderate concentrations resulted in low toxicities in the long term. Our results indicate that negatively charged PSL NPs provide safer alternatives as cargo carriers in drug delivery applications. Moreover, the variations in NP size, concentration, and exposure time, along with the use of hybrid systems, have significant roles in nanoparticle-based drug delivery applications in terms of their effects on living organisms.

Building Reversible Nanoraspberries.

The adsorption mechanism of small positively charged silica nanoparticles (SiO2 NPs) onto larger polystyrene latex nanoparticles (PSL NPs) forming hybrid particles was studied. CryoTEM showed the morphology of these supraparticles to be raspberry-like. After surface modification of the SiO2 NPs, the optimum pH regime to initiate the formation of nanoraspberries was determined. Thereafter, their size evolution was evaluated by dynamic light scattering for different surface charge densities. Reversibility of nanoraspberry formation was shown by cycling the pH of the mixture to make interparticle forces either attractive or repulsive, while their stability was confirmed experimentally. The number of SiO2 NPs on the PSL NPs as determined with cryoTEM matched the theoretically expected maximum number. Understanding and controlling the relevant parameters, such as size and charge of the individual particles and the Debye length, will pave the way to better control of the formation of nanoraspberries and higher-order assemblies thereof.

Measurement of the colloidal particle concentration and size within a drop using the time-shift technique

Liquid drops containing particles of nano to micron size are omnipresent in the chemical, pharmaceutical and process industries. In order to optimize such processes, there is a need to characterize these drops in terms of size and colloidal particle concentration. This study is devoted to estimating the colloidal nanoparticle concentration within such drops by using the time-shift technique. The estimation is achieved using two different approaches. The first utilizes the signal strength generated by light scattering from the particles in the drop relative to reflective scattering from the undisturbed drop surface. The second approach monitors the attenuation of the portion of the time-shift signal generated by second-order refractive scattering, i.e. light which has passed twice through the drop. These methods have been simulated using previously developed light scattering codes based on Monte Carlo ray tracing. Corresponding experiments have been implemented to validate these two estimation methods. For this, colloidal drops were generated by mixing water with the polystyrene latex nanoparticles and varying the volume concentration. Good agreement between the experimental and simulation results has been achieved, indicating that the time-shift technique can be further developed to meet this measurement task.

Use of electrical field-flow fractionation for gold nanoparticles after improving separation efficiency by carrier liquid optimization

Electrical field-flow fractionation (ElFFF) is a useful separation technique for nanoparticles, however, it has been limited by polarization/electrical double layer formation which reduces an effective field for separation. With an appropriate direct current (DC) applied voltage, sodium carbonate, FL-70, Triton X-100 and acetonitrile were explored as additive substances for preparation of carrier liquid used in normal ElFFF to enhance an amplitude of effective field by their ionic redox-active species, ionic and nonionic surfactant and wide electrochemical potential window nonionic organic solvent properties, respectively. Effective field was indirectly measured in each carrier liquid by investigating retention behavior of polystyrene latex nanoparticles and gold nanoparticles. Effective field improvement was observed in all carrier liquid types (except FL-70) by which the highest effective field existed in 16 μM sodium carbonate at 1.70 V and 0.01% (V/V) Triton X-100 and 50% (V/V) acetonitrile at 1.90 V as compared to deionized water at 1.90 V. In addition, those carrier liquids were applied for separation of 5 nm and 15 nm gold nanoparticles mixture by which Triton X-100 exhibited the best separation resolution (Rs = 1.11).

Accurate Measurement of Self-diffusion Coefficient of Nanoparticles in Aqueous Solutions Using a Dynamic Light Scattering

One of the standard methods used to measure the hydrodynamic diameter of nanoparticles is photon correlation spectroscopy, especially dynamic light scattering (DLS). In principle, this technique is to analyze correlation function of the scattered light from the nanoparticles undergoing Brownian motion in solution and to calculate the diffusion coefficient from the correlation function which is converted into the hydrodynamic diameter. However, when using this technique, one needs to pay careful attention to interaction effects (i.e., particle-particle and particle-solvent interactions) on the diffusion coefficient of the particles in solution. If not, then incorrect information can be obtained on the self-diffusion coefficients of nanoparticles. In order to facilitate a strict procedure for obtaining real size of the nanoparticles in solution, we used 20 nm, 50 nm and 100 nm-nominal polystyrene latex (PSL) nanoparticle solutions for DLS measurement. We represented that a rigorous scrutinizing the concentration dependence of the diffusion coefficient of the PSL nanoparticles made it possible to separate the interaction effect from the diffusion phenomena of the PSL nanoparticles suspended in water and to give real size of the PSL nanoparticles.

Morphology evolution of functionalized styrene and methyl methacrylate copolymer latex nanoparticles by one-step emulsifier-free emulsion polymerization

Evolution of morphology in the latex nanoparticles synthesized by emulsion polymerization methods has been an interesting challenge. Herein, a fast and facile methodology was developed for the synthesis of functionalized latex nanoparticles based on polystyrene (PS) and poly(methyl methacrylate) (PMMA) by one-step emulsifier-free emulsion copolymerization with functional acrylic comonomers. These functional latex nanoparticles display different particle size in the range of 150–1400 nm and morphologies depending on the surface functional groups. Morphological investigation of the functionalized latex nanoparticles by scanning electron microscopy and transmission electron microscopy display that PMMA and PS latex nanoparticles with amide and hydroxyl functionalities have cauliflower like morphology with a non-smooth surface. The PS latex nanoparticles functionalized with epoxy groups have vesicular morphology in colloidal and red blood cell-like morphology in solid state. The PMMA latex nanoparticles containing epoxy and hydroxyl functionalities on the surface and also the PS latex nanoparticles functionalized with amide groups display highly monodispersed spherical morphologies. The porous surface was observed for the spherical PMMA and PS latex nanoparticles functionalized with carboxylic acid groups by using 4,4′-azobis(4-cyanovaleric acid) as the initiator. Different morphologies observed for the functional PS and PMMA latex nanoparticles prepared by one-step emulsifier-free emulsion polymerization are very interesting and have potential applications in drug-delivery, bioimaging, cell-labeling, and chemosensors.

Effect of Temperature on 60nm and 100nm Nanosphere Size Standard using Dynamic Light Scattering

It is difficult to use kinetic motion as a measurement tool without temperature affecting the results. In this study, the size of a known nanosphere was used to monitor the effect of temperature towards particle size determination using dynamic light scattering principles. Temperature deviations are always picked up by size measurement using the principle of Brownian motion. The particle size of 60nm and 100nm polystyrene latex nanoparticles in 10mM NaCl solution was measured at four different temperatures set points of 20, 25, 30, 35 and 40°C using dynamic light scattering mechanism. As a result, the size of polystyrene latex nanoparticles was increased with the increases of the temperature. Therefore, for particle size analysis using dynamic light scattering mechanism the temperature of the test must be maintained at 25°C in order to obtain accurate measurement.

Aquatic behavior and toxicity of polystyrene nanoplastic particles with different functional groups: Complex roles of pH, dissolved organic carbon and divalent cations

Herein we systematically examined the roles of water chemistry (pH, dissolved organic carbon (DOC), and divalent cations) and particle surface functionality that control the aqueous stability, aggregation, and toxicity of engineered nanoplastic particles in simulated natural environmental conditions. Model polystyrene latex nanoparticles (PLNPs) with three different functional groups, namely unmodified (uPLNPs), amine-modified (aPLNPs), and carboxyl-modified (cPLNPs), were investigated. Results indicate that the presence of only DOC increased the surface charge and exhibited negligible effects on the size distribution of the PLNPs in aqueous suspensions. The presence of the divalent cations (Ca2+ and Mg2+) was observed to decrease the surface charge and increase the size of the PLNPs. The coexistence of DOC and the divalent cations enhanced the extent of aggregation of the PLNPs in the water columns. The surface modification and pH were sensitive factors influencing the stability of PLNPs during long-term suspension when DOC and the divalent cations coexisted. Direct visual further testified the conclusions on the combined effects of solution and surface chemistry parameters. Furthermore, in situ transmission electron microscope observations revealed that the enhancement of PLNP aggregation in the presence of DOC and the divalent cation was caused by bridge formation. Toxicity test indicated the PLNPs exhibited acute toxicity and physical damage to Daphnia magna. The more complex the solution conditions, the more toxicity the aPLNPs and cPLNPs. Analysis of mode of toxic action implied that the PLNPs mainly caused the accumulation of oxidative damage to the gut of D. magna.

Direct measurements of colloidal behavior of polystyrene nanoparticles into budding yeast cells using atomic force microscopy and confocal microscopy

The colloidal behavior of positively charged polystyrene latex (PSL) nanoparticles (NPs) toward yeast cells (Saccharomyces cerevisiae) was investigated using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). AFM imaging revealed that the conically-shaped pits connected with endocytosis were observed in 154 mM NaCl, and the surface was completely covered with NPs within 60 s in 5 mM NaCl. AFM force measurements revealed that the adhesion rate of NPs in 5 mM NaCl was faster than that in 154 mM NaCl. This strongly suggested that in 5 mM NaCl, the NPs accumulated on the cell surface over a short time followed by cell death. Furthermore, the accumulation of NPs on the cell surface in 5 mM NaCl could be suppressed by adding polyethylene glycol to the medium, resulting in an increase in the number of living cells. This suggests that the adhesion rate of NPs primarily depended on the interaction forces between the surfaces, and the viscosity of the medium. Thus, the colloidal behavior of the positively charged PSL NPs toward yeast cells was controlled by the balance between the adhesion rate of NPs on the cells and the uptake rate of NPs into the cells. Additionally, the uptake of the PSL NPs and an endocytosis marker into the cells was inhibited by Latrunculin B and NaN3. However, their locations without inhibitor treatment were obviously different, indicating that NPs were not transported to the vacuole and accumulated in the vesicles.

Control of colloidal behavior of polystyrene latex nanoparticles and their cytotoxicity toward yeast cells using water-soluble polymers

Positively charged polystyrene latex (PSL) nanoparticles (NPs) dispersed in physiological saline (154 mM NaCl solution) are taken up by yeast cells. However, in low ionic strength solutions, the yeast cells are covered with the NPs, leading to cell death. The environmental conditions under which NPs are taken up are therefore limited. In this study, we attempted to control the uptake of positively charged PSL NPs by Saccharomyces cerevisiae in 5 mM NaCl solution using a water-soluble polymer. Addition of a small amount of anionic sodium carboxymethylcellulose (CMC), which has a carboxyl group, to 5 mM NaCl solution allowed the uptake of PSL NPs by living yeast cells. In contrast, non-ionic methylcellulose did not affect the NP behavior. This is because the negatively charged CMC adhered to the positively charged PSL NP surfaces and the surface charge changed from positive to negative. Atomic force microscopy using a single-NP probe consisting of one NP immobilized on the flattened end of the silicon nitride tip showed that CMC significantly reduced the interaction force between a negatively charged living yeast cell and a positively charged PSL NP.

Impact of surface-functionalized polystyrene latex nanoparticles on the growth of Methanosarcina barkeri

The impact of surface-functionalized polystyrene latex (PSL) nanoparticles (NPs) on Methanosarcina barkeri was assessed under anaerobic conditions. M. barkeri was cultured in DSM 120 medium in the presence of PSL NPs. As a result, amine-modified PSL NPs (PS-NH2) inhibited growth, whereas carboxylate-modified PSL NPs had no negative impact on growth. Interestingly, confocal observation revealed that the cells were alive even though the methane was hardly generated and no evidence of NP adhesion on the cell surfaces and NP internalization in the cells were identified. This is because the zeta potential of PS-NH2 decreased with an increase of the concentrations of yeast extract and Casitone in the DSM120 medium and the polarity changed from positive to negative. In addition, removal of yeast extract and Casitone from the DSM 120 medium induced the precipitation of phosphate compound containing calcium and magnesium. From the above experimental results, when PS-NH2 are added to DSM 120 medium, the phosphorus required for cell growth forms a phosphate compound on the PS-NH2 surface due to adsorption of components stabilizing calcium and magnesium in the medium, as a result of which the phosphorus source is deficient and growth is inhibited.

Application of a novel new multispectral nanoparticle tracking technique

Fast, reliable, and accurate particle size analysis techniques must meet the demands of evolving industrial and academic research in areas of functionalized nanoparticle synthesis, advanced materials development, and other nanoscale enabled technologies. In this study a new multispectral particle tracking analysis (m-PTA) technique enabled by the ViewSizer™ 3000 (MANTA Instruments, USA) was evaluated using solutions of monomodal and multimodal gold and polystyrene latex nanoparticles, as well as a spark eroded polydisperse 316L stainless steel nanopowder, and large (non-Brownian) borosilicate particles. It was found that m-PTA performed comparably to the DLS in evaluation of monomodal particle size distributions. When measuring bimodal, trimodal and polydisperse solutions, the m-PTA technique overwhelmingly outperformed traditional dynamic light scattering (DLS) in both peak detection and relative particle concentration analysis. It was also observed that the m-PTA technique is less susceptible to large particle overexpression errors. The ViewSizer™ 3000 was also found to be successful in accurately evaluating sizes and concentrations of monomodal and bimodal sinking borosilicate particles.

Measurement of the Density of Engineered Silver Nanoparticles Using Centrifugal FFF-TEM and Single Particle ICP-MS.

A methodology has been developed to measure nanoparticle mass and density, by combining centrifugal field-flow fractionation (CeFFF; more commonly called sedimentation FFF or SdFFF) and transmission electron microscopy (TEM). Particle effective mass obtained from CeFFF retention data and particle size obtained from the TEM images were used to calculate the nanoparticle density. The method was initially applied to measure the density of monodispersed polystyrene latex nanoparticles. Measured densities for latex nanoparticles of 160-300 nm in diameter were in the range of 1041-1063 kg m-3 with standard deviations of 0.6-1.1%. Densities of engineered silver nanoparticles with nominal diameters of 30, 60, 75, and 100 nm were measured using this methodology. For all four silver nanoparticle samples, the measured densities were 18-24% lower than the nominal density of metallic silver, with an overall mean value of 7900 ± 675 kg m-3. Density values calculated using nanoparticle mass values obtained from single particle inductively coupled plasma-mass spectrometry (spICP-MS) measurements, corroborated the CeFFF-TEM results. The difference in the density of the silver nanoparticles compared to that of bulk silver suggests that the synthesis process could impart 20-37% porosity in silver nanoparticles. The data has important implications in the fields of nanomaterial, nanomedicine and nanotoxicology, where assumption of the bulk density for nanoparticles can result in erroneous estimation of parameters such as mass, size, porosity, and dosage. The presented methodology provides a straightforward and reproducible means for measurement of the density and porosity of engineered nanoparticles with a wide range of density and size.