Surface Modification Of Nanoparticles Research Articles

Preparation of Pickering Emulsions Stabilized by Modified Silica Nanoparticles via the Taguchi Approach.

In this study, oil-in-water Pickering emulsions (PEs) were prepared by modified silica nanoparticles (MSNs) with cetyltrimethylammonium bromide (CTAB) using the Taguchi approach. The surface modification of SiO2 nanoparticles (NPs) was performed in different conditions, temperatures, pH levels, and amounts of CTAB as a coating agent, followed by an evaluation of their physicochemical properties. After treatment of the SiO2 NPs, the relationship of the MSNs’ surface properties and their efficiency in stabilizing Pickering emulsions was investigated by considering the zeta potential (ZP) and emulsion physical stability as main responses, respectively. Results disclosed were then supported by additional characterization, such as thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), and scanning electron microscopy. Results demonstrated that temperature has the most important role in the treatment of SiO2 nanoparticles, and allows for the identification of the best experimental conditions, i.e., range of zeta potential of MSNs to produce more efficient NPs, as well as the best stabilization of PEs.

Fabrication and characterization of inner selective antibiofouling forward osmosis hollow fiber membranes for simultaneous wastewater treatment and desalination

Forward osmosis (FO) hollow-fiber membranes were prepared by in situ thin layer assembly of polyethyleneimine (PEI) on antifouling PES-based porous nanocomposite membranes during membrane formation by spinning and phase inversion, via incorporation of surface-modified silver nanoparticles (NPs) in the dope solution and addition of PEI in the bore liquid; after cross-linking with glutaraldehyde the FO selective layer was obtained at the lumen surface while the shell surface had ultrafilter (UF) properties. This design enabled the utilization of the FO membranes in active layer facing draw solution (DS) orientation to employ maximum effective osmotic pressure, while the UF layer in combination with the antibacterial NPs was supposed to reduce fouling by the wastewater used as feed solution (FS). The quality of the active layer assembly was characterized using atomic force microscopy and scanning electron microscopy analyses, as well as salt rejection, structural parameter (S), and molecular weight cut-off (MWCO) measurements. The separation performance of these membranes was evaluated in an osmotic membrane bioreactor (OMBR) system, showing for the best FO nanocomposite membranes less than 10% fouling and flux reduction over 5 cycles of operation over a total period of 5 days. The best-suited membrane showed promising separation performance in the OMBR system by providing 43.4 LMH water flux and only around 0.2 g/l specific reverse salt flux (SRSF) with 1 M NaCl and DI water serving as DS and feed, respectively. This study focused also on distinctive performance criteria in combined FO and OMBR systems, such as the membrane’s potential in a pretreatment step of brine streams (used as DS) to provide proper feed composition for RO units and introduced a new specific performance index (SPI) for better characterization of FO membranes which summarizes all essential characteristics of the membrane application, instead of using existing structural parameter equations for membrane characterization. The best-suited FO membrane offered an SPI of 778.2 gl−1 m−2 h−1, meaning 778.2 g/l reduction of TDS in DS per unit membrane surface area per hour.

Exploring the interfacial adsorption capability of bovine serum albumin

Proteins play a vital role in many applications related to protein corona, thin-film formation, surface modification of nanoparticles, biosensors, and other biological activities. Bovine serum albumin (BSA) is widely used in such applications. Many complex fluids can be engineered for their rheological and tribological activities using additives showing beneficial interfacial properties. The use of biocompatible additives definitely enhance the performance of such complex fluids for biomedical and biotechnological applications. Here we show the adsorption of BSA on the aqueous subphases. Appreciable surface pressure has been achieved for the BSA layer adsorbed on the aqueous subphases in the Langmuir trough. The isotherms with reference to time also justify the gradual adsorption of BSA on the air-liquid interface. The current findings can be effectively used for designing the thin films or coatings for biomedical applications and the biomechanical or micromechanical objects leading to improved rheological and tribological characteristics.

Screening strategies for surface modification of lipid-polymer hybrid nanoparticles

Lipid-polymer hybrid nanoparticles are promising platforms in the field of targeted drug delivery, integrating the positive features of polymeric and lipid nanocarriers. However, the use of bulk procedures in lipid-polymer hybrid nanoparticles formulation is hindering their large-scale manufacturing. Therefore, the aim of this study is to explore the suitability of alternative formulation methods, such as microfluidics, to obtain surface-tunable nanoparticles displaying suitable characteristics. Formulations were prepared by single-step nanoprecipitation or using a micromixer chip. The nanocarriers were then surface-modified with an aptamer and an antibody, two common nanoparticle vectorization strategies, developing an optimized functionalization protocol. Both naked and surface-modified nanoparticles were characterized in terms of size, polydispersity, zeta potential and morphology. Moreover, the aptamer/antibody association efficiency was also determined. Nano-sized monodisperse nanoparticles, exhibiting a spherical core–shell structure, were obtained through both procedures. Furthermore, all the nanocarriers were successfully functionalized, showing association efficiency values above 70%. Interestingly, microfluidic-based nanoparticles displayed a smaller size and a more positive zeta potential than those prepared by single-step nanoprecipitation. Outcomes suggest both techniques led to lipid-polymer hybrid nanoparticles displaying a similar functionalization efficiency. Conversely, the microfluidic approach provided an improved control over critical parameters, as particle size or charge, constituting an interesting alternative to traditional formulation procedures.

Acid-Responsive Multifunctional Zeolitic Imidazolate Framework-8 (ZIF-8) Nanocomposites for Tumor Chemo-Photothermal Synergistic Therapy.

Camptothecin (CPT), a broad-spectrum anticancer drug, has been extensively used clinically. However, its hydrophobic properties seriously hinder its antitumor therapeutic effect. Herein, we synthesized acid-degradable Fe3O4@poly(vinylpyrrolidone) (Fe3O4@PVP)/gold nanoclusters@zeolitic imidazolate framework-8 composite nanoparticles (ZIF-8CNPs) via a facile method and utilized them as carriers to efficiently load CPT. The excellent fluorescence properties of gold nanoclusters (AuNCs) and the photothermal properties of Fe3O4@poly(vinylpyrrolidone) (Fe3O4@PVP) endowed the nanocomposites with excellent cell imaging and photothermal functions. In addition, the surface modification of the composite nanoparticles with folic acid-grafted bovine serum albumin (FA-BSA) enables them to efficiently target tumor cells. Once FA-BSA/ZIF-8CNPs-CPT are taken up by tumor cells and irradiated with a near-infrared laser, the nanoparticles show a highly effective inhibitory effect against various tumor cells through a chemo-photothermal synergistic effect. Hence, it is conceivable that this acid-responsive multifunctional ZIF-8 nanocomposite has promising bioapplication prospects in cancer treatment.

High-Density Branched PEGylation for Nanoparticle Drug Delivery.

The surface modification of nanoparticles (NP) with a dense layer of polyethylene glycol (PEG) has been widely used to improve NP circulation time, bioavailability, and diffusion through biological barriers [e.g. extracellular matrix (ECM), mucus]. While linear PEG coatings are commonly used, branched PEG coatings have not been widely explored as a design parameter for NP drug delivery systems. NPs were densely coated with either linear 2, 5, 10kDa linear PEG or with 10kDa star-shaped, 4-arm branched PEG. NP cellular uptake was evaluated in HEK-293T and A549 cells. NP stability was evaluated in fetal bovine serum over 24h using dynamic light scattering. Diffusion of NPs within a Matrigel ECM model and sputum (mucus) collected from individuals with cystic fibrosis (CF) lung disease were analyzed through multiple particle tracking. PEG-coated NPs appeared more stable in serum compared to uncoated NPs, but the reduction in total protein adsorbed was most significant for branched PEG coated NP. All PEGylated NPs had similar cellular uptake in HEK-293T and A549 cells. Interestingly, branched-PEG coated NPs had the largest diffusion coefficient and moved most rapidly through Matrigel. However in CF mucus, linear 2 and 5 kDa PEG coated NPs had the largest fraction of rapidly diffusing particles while branched PEG coated NPs had less hindered mobility compared to linear 10 kDa PEG coated NPs. Branched PEGylation may have the potential to increase NP efficiency in reaching target cells based on an apparent increase in diffusion through an ECM model while maintaining NP stability and uptake in target cells comparable to their linear PEG counterparts.

Effect of the Surface Modification of Silica Nanoparticles on the Viscosity and Mechanical Properties of Silica/Epoxy Nanocomposites

ABSTRACT Silica/epoxy hybrid resin has high viscosity owing to its particle size and aggregation in the epoxy matrix, which leads to poor usability and processability. To control the size of the silica nanoparticles, surface modification of the colloidal silica (12 nm) was conducted in two steps using a silane coupling agent. The silica nanoparticles were then dispersed in the epoxy resin using an amphiphilic solvent with a high boiling point instead of mechanical dispersion. A nanosilica/epoxy hybrid resin with a low viscosity was obtained. The hybrid resin containing 3 wt% silica nanoparticles obtained a viscosity value that is 1.2% that of the neat epoxy resin. The tensile and flexural strengths of the silica/epoxy nanocomposite, as well as the impact strength of the silica/epoxy nanocomposite, were improved by plastic deformation cause by the introduction of silica nanoparticles. With silica nanoparticles loading of 10 wt%, the tensile strength of the silica/epoxy nanocomposite increased by 24%, and the impact strength increased by 112%. For higher amounts of loaded silica nanoparticles, the tensile strength of the silica/epoxy nanocomposite continuously increased, while the impact strength decreased.

Quantum efficiency of europium doped LaPO4 phosphors for UV sensing applications

The radiation conversion phenomenon is used for UV sensing applications with rare earth doped phosphors. This paper presents the results of structural and optical measurements of undoped and europium doped LaPO4 phosphors. LaPO4 phosphors with 1% mol, 2% mol, and 5% mol of europium were fabricated by the co-precipitation method. The effect of Eu3+ concentrations on the luminescence characteristics under UV LED excitation was investigated. The maximum quantum efficiency of luminescence (c.a. 82%) was obtained in sampled doped with 5% of europium. Full Text: PDF ReferencesM. Runowski, "Nanotechnologia – nanomateriały, nanocząstki i wielofunkcyjne nanostruktury typu rdzeń/powłoka", Chemik 68, 9, 766-775 (2014). DirectLink J. Zhou, J.L. Leano Jr., Z. Liu, D. Jin, K.-L. Wong, R.S. Liu, et al., "Impact of Lanthanide Nanomaterials on Photonic Devices and Smart Applications", Small 14, 1801882 (2018). CrossRef Z. Li, Y. Zhang, G. Han, "Lanthanide-Doped Upconversion Nanoparticles for Imaging-Guided Drug Delivery and Therapy", Springer Series in Biomater. Sci. Eng. 6, 139-164, (2016). CrossRef M. Lin, Y. Zhao, S. Wang, M. Liu, Z. Duan, Y. Chen, et al., "Recent advances in synthesis and surface modification of lanthanide-doped upconversion nanoparticles for biomedical applications", Biotechnol. Adv. 30, 1551-1561 (2012). CrossRef H. Su, Y. Nie, H. Yang, D. Tang, K. Chen, T. Zhang, "Improving the thermal stability of phosphor in a white light-emitting diode (LED) by glass-ceramics: Effect of Al2O3 dopant", J. Eur. Ceram. Soc. 38, 2005-2009 (2018). CrossRef J. Huang, X. Hu, J. Shen, D. Wu, C. Yin, R. Xiang, et al., "Facile synthesis of a thermally stable Ce3+:Y3Al5O12 phosphor-in-glass for white LEDs", Cryst. Eng. Comm 17, 7079-7085 (2015). CrossRef R. Zhang, H. Lin, Y. Yu, D. Chen, J. Xu, Y. Wang, "A new-generation color converter for high-power white LED: transparent Ce3+:YAG phosphor-in-glass", Laser Photon. Rev. 8, 158-164 (2014). CrossRef B. Zheng, Y. Bai, H. Chen, H. Pan, W. Ji, X. Gong, et al., "Near-Infrared Light-Excited Upconverting Persistent Nanophosphors in Vivo for Imaging-Guided Cell Therapy", ACS Appl. Mater. Interfaces 10, 19514 (2018). CrossRef J. Qiao, G. Zhou, Y. Zhou, Q. Zhang, Z. Xia, "Divalent europium-doped near-infrared-emitting phosphor for light-emitting diodes", Nature Communications 10 (1), 5267 (2019). CrossRef V. Singh, A. Kumar, C. Mehare, H. Jeong, S. Dhoble, "UV/VUV excited photoluminescence of Tb3+ doped LaPO4 green emitting phosphors for PDP applications", Optik 206, 163733 (2020). CrossRef G. Han, Y. Wang, C. Wu, J. Zhang, "Hydrothermal synthesis and vacuum ultraviolet-excited luminescence properties of novel Dy3+-doped LaPO4 white light phosphors", Mat. Res. Bull. 44 (12), 2255-2257 (2009). CrossRef K. S. Gupta, P. S. Ghosh, M. Sahu, K. Bhattacharyya, R. Tewari, V. Natarajan, "Intense red emitting monoclinic LaPO4:Eu3+ nanoparticles: host–dopant energy transfer dynamics and photoluminescence properties", RSC Adv. 5, 58832-58842 (2015). CrossRef

Bridging Size and Charge Effects of Mesoporous Silica Nanoparticles for Crossing the Blood-Brain Barrier.

The blood–brain barrier (BBB) is a highly selective cellular barrier that tightly controls the microenvironment of the central nervous system to restrict the passage of substances, which is a primary challenge in delivering therapeutic drugs to treat brain diseases. This study aimed to develop simple surface modifications of mesoporous silica nanoparticles (MSNs) without external stimuli or receptor protein conjugation, which exhibited a critical surface charge and size allowing them to cross the BBB. A series of MSNs with various charges and two different sizes of 50 and 200 nm were synthesized, which showed a uniform mesoporous structure with various surface zeta potentials ranging from +42.3 to −51.6 mV. Confocal microscopic results showed that 50 nm of strongly negatively charged N4-RMSN50@PEG/THPMP (∼−40 mV) could be significantly observed outside blood vessels of the brain in Tg(zfli1:EGFP) transgenic zebrafish embryos superior to the other negatively charged MSNs. However, very few positively charged MSNs were found in the brain, indicating that negatively charged MSNs could successfully penetrate the BBB. The data were confirmed by high-resolution images of 3D deconvoluted confocal microscopy and two-photon microscopy and zebrafish brain tissue sections. In addition, while increasing the size to 200 nm but maintaining the similar negative charge (∼40 mV), MSNs could not be detected in the brain of zebrafish, suggesting that transport across the BBB based on MSNs occurred in charge- and size-dependent manners. No obvious cytotoxicity was observed in the CTX-TNA2 astrocyte cell line and U87-MG glioma cell line treated with MSNs. After doxorubicin (Dox) loading, N4-RMSN50@PEG/THPMP/Dox enabled drug delivery and pH-responsive release. The toxicity assay showed that N4-RMSN50@PEG/THPMP could reduce Dox release, resulting in the increase of the survival rate in zebrafish. Flow cytometry demonstrated N4-RMSN50@PEG/THPMP had few cellular uptakes. Protein corona analysis revealed three transporter proteins, such as afamin, apolipoprotein E, and basigin, could contribute to BBB penetration, validating the possible mechanism of N4-RMSN50@PEG/THPMP crossing the BBB. With this simple approach, MSNs with critical negative charge and size could overcome the BBB-limiting characteristics of therapeutic drug molecules; furthermore, their use may also cause drug sustained-release in the brain, decreasing peripheral toxicity.

Effects of neuronal cell adhesion molecule L1 and nanoparticle surface modification on microglia

Microelectrode arrays for neural recording suffer from low yield and stability partly due to the inflammatory host responses. A neuronal cell adhesion molecule L1 coating has been shown to promote electrode-neuron integration, reduce microglia activation and improve recording. Coupling L1 to surface via a nanoparticle (NP) base layer further increased the protein surface density and stability. However, the exact L1-microglia interaction in these coatings has not been studied. Here we cultured primary microglia on L1 modified surfaces (with and without NP) and characterized microglia activation upon phorbol myristate acetate (PMA) and lipopolysaccharide (LPS) stimulation. Results showed L1 coatings reduced microglia's superoxide production in response to PMA and presented intrinsic antioxidant properties. Meanwhile, L1 decreased iNOS, NO, and pro-inflammatory cytokines (TNF alpha, IL-6, IL-1 beta), while increased anti-inflammatory cytokines (TGF beta 1, IL-10) in LPS stimulated microglia. Furthermore, L1 increased Arg-1 expression and phagocytosis upon LPS stimulation. Rougher NP surface showed lower number of microglia attached per area than their smooth counterpart, lower IL-6 release and superoxide production, and higher intrinsic reducing potential. Finally, we examined the effect of L1 and nanoparticle modifications on microglia response in vivo over 8 weeks with 2-photon imaging. Microglial coverage on the implant surface was found to be lower on the L1 modified substrates relative to unmodified, consistent with the in vitro observation. Our results indicate L1 significantly reduces superoxide production and inflammatory response of microglia and promotes wound healing, while L1 immobilization via a nanoparticle base layer brings added benefit without adverse effects. Statement of significanceSurface modification of microelectrode arrays with L1 has been shown to reduce microglia coverage on neural probe surface in vivo and improves neural recording, but the specific mechanism of action is not fully understood. The results in this study show that surface bound L1 reduces superoxide production from cultured microglia via direct reduction reaction and signaling pathways, increases anti-inflammatory cytokine release and phagocytosis in response to PMA or LPS stimulation. Additionally, roughening the surface with nanoparticles prior to L1 immobilization further increased the benefit of L1 in reducing microglia activation and oxidative stress. Together, our findings shed light on the mechanisms of action of nanotextured and neuroadhesive neural implant coatings and guide future development of seamless tissue interface.

Determination of the Highly Sensitive Carboxyl-Graphene Oxide-Based Planar Optical Waveguide Localized Surface Plasmon Resonance Biosensor.

This study develops a highly sensitive and low-cost carboxyl-graphene-oxide-based planar optical waveguide localized surface plasmon resonance biosensor (GO-OW LSPR biosensor), a system based on measuring light intensity changes. The structure of the sensing chip comprises an optical waveguide (OW)-slide glass and microfluidic-poly (methyl methacrylate) (PMMA) substrate, and the OW-slide glass surface-modified gold nanoparticle (AuNP) combined with graphene oxide (GO). As the GO has an abundant carboxyl group (–COOH), the number of capture molecules can be increased. The refractive index sensing system uses silver-coated reflective film to compare the refractive index sensitivity of the GO-OW LSPR biosensor to increase the refractive index sensitivity. The result shows that the signal variation of the system with the silver-coated reflective film is 1.57 times that of the system without the silver-coated reflective film. The refractive index sensitivity is 5.48 RIU−1 and the sensor resolution is 2.52 ± 0.23 × 10−6 RIU. The biochemical sensing experiment performs immunoglobulin G (IgG) and streptavidin detection. The limits of detection of the sensor for IgG and streptavidin are calculated to be 23.41 ± 1.54 pg/mL and 5.18 ± 0.50 pg/mL, respectively. The coefficient of variation (CV) of the repeatability experiment (sample numbers = 3) is smaller than 10.6%. In addition, the affinity constants of the sensor for anti-IgG/IgG and biotin/streptavidin are estimated to be 1.06 × 107 M−1 and 7.30 × 109 M−1, respectively. The result shows that the GO-OW LSPR biosensor has good repeatability and very low detection sensitivity. It can be used for detecting low concentrations or small biomolecules in the future.

Fundamental insight into the interaction between a lithium salt and an inorganic filler for ion mobility using a synergic theoretical-experimental approach

The present paper aims at providing a fundamental insight into the interaction between a lithium salt and an inorganic filler in a perspective of lithium mobility. Through a synergistic approach, coupling experimental results and molecular dynamics simulations, the influence of the surface chemical state of the nanosilica Stöber-type on the dissociation of LiTFSI and its impact on the lithium conduction properties are studied. For this purpose, the surface modification of silica nanoparticles was performed by different methods such as calcination, lithiation and capping with organosilane. The impact of the surface modification on the dissociation of the lithium salt is further investigated by electrochemical impedance spectroscopy after impregnation of the material with a defined amount of lithium salt. The combined experimental and in silico analyses of the results, performed for the first time on such systems, allow a detailed understanding of the interaction between the salt and the support and should prove itself useful for the future design of hybrid polymer electrolytes in new generation batteries.

Surface-Modified Nanoparticle Gelled-Acid System Stimulates Without Formation Damage

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22443, “Surface-Modified Nanoparticle-Based Novel Gelled-Acid System: A Unique Formation-Damage-Free Well-Stimulation Technology,” by Rajendra Kalgaonkar, SPE, and Nour Baqader, SPE, Saudi Aramco. The paper has not been peer reviewed. Copyright 2022 International Petroleum Technology Conference. Reproduced by permission. Gelled-acid systems based on the gelation of hydrochloric acid (HCl) are used extensively in both matrix and fracture acidizing to prevent acidizing-fluid leakoff. However, these systems can lead to formation damage. To mitigate this risk, the authors have developed a self-breaking, formation-damage-free, novel nanoparticle-based gelled-acid system to replace polymer-based gelled-acid systems. Nanoparticle-Based Gelled-Acid System The complete paper showcases a method for gelling up an acid formulation for stimulating a carbonate reservoir. The technique is based on surface-modified nanoparticles. The new gelled-acid system does not contain any polymer-based gelling agents. It consists of inorganic nanoparticles with a gelation-activator material to activate viscosification. The increase in viscosity will lead to a slowdown of the reaction rate of the acid with the carbonate formation. Suitable functionalities are used to surface-modify the nanoparticles to stabilize them in acidic media. The treatment fluid can be pumped downhole as a single homogeneous fluid system in the same pumping stage. The nanoparticles are easily miscible with the acid formulation without any need for the batch-mixing processes that may be required for a polymer-based gelled-acid system to account for polymer hydration. Thus, this formulation can be mixed easily while pumping the acidic fluid downhole. This ensures that the new gelled-acid system can increase operational efficiency by reducing operational time substantially. Nanoparticle gelation takes place in situ in the acid fluid and does not require a separate pumping stage to introduce the activator. The gelation of nanoparticles is predominantly a pH-based phenomenon. The gelation rate can be influenced also by temperature. As the fluid’s temperature increases, the treatment fluid viscosifies, thus diverting the tail-end acid to less-permeable zones in the reservoir. As the acid spends after reacting with the carbonate formation and the pH of the system increases beyond a pH of 4, the nanoparticles lose their ability to further viscosify the acid, thus reducing the viscosity of the fluid system. This enables easy flowback of the fluid post-treatment. Because the viscosifying material used in the present invention is a nanoparticulate, it will be potentially nondamaging to the formation because of effective flowback and no residual deposition inside the formation.

Surface modification of SiO2 nanoparticles for bacterial decontaminations of blood products

Bacterial infections can be caused by contamination of labile blood products with specific bacteria, such as Staphylococcus aureus and Staphylococcus epidermidis. Hospital equipment, bio-protective equipment, delivery systems, and medical devices can be easily contaminated by microorganisms. Multidrug-resistant bacteria can survive on various organic or inorganic polymeric materials for more than 90 days. Inhibiting the growth and eradicating these microorganisms is vital in blood transfusion processes. Blood bags and other related medical devices can be improved by the incorporation of organic or inorganic nanomaterials, particularly silicon dioxide (SiO2) nanoparticles. The addition of solid organic or inorganic nanoparticles to synthetic polymers or biopolymers can provide new properties in addition to antimicrobial activity. Among these NPs, formulations composed of SiO2 nanoparticles and polymers have been shown to improve the mechanical and antimicrobial properties of catheters, prosthetic inserts, blood bags, and other medical devices SiO2 nanoparticles possess several advantages, including large-scale synthetic availability, simple one-pot synthesis methods, porous structure for loading antibacterial agents, good biocompatibility, and thermal stability. Plasticized polyvinyl chloride is the main polymer, which has been functionalized by these nanoparticles. In this review, we discuss the recent advances and challenges regarding the functionalization of polyvinyl chloride by SiO2 nanoparticles to hinder bacterial contaminations in blood products.

Study of Lysine and Asparagine as Capping Agent for Gold Nanoparticles

The wide application of gold nanoparticles has attracted much attention to the development of research in gold nanoparticles. In this study, the gold nanoparticles were prepared by chemical reduction method using potassium tetrachloroaurate as the gold source and sodium borohydride as reducer agent. The formation of gold nanoparticles was confirmed by surface plasmon spectra in ultraviolet-visible spectroscopy at wavelength 507 nm. The capping process of gold nanoparticles was studied using two different charges of amino acids. The asparagine had used as uncharge amino acid and lysine as a positive charge amino acid. The redshift in surface plasmon spectra showed the aggregation of the gold nanoparticles after being capped with amino acids that indicates the surface modification. The amine and carboxylate group was present on the gold nanoparticle surface after being capped with amino acids. The zeta potential results indicate the lysine capped gold nanoparticles have slightly higher stability than the asparagine capped gold nanoparticles. These stability and surface modification of gold nanoparticles are expected to increase their utilization on biological and medical applications.

Surface Modification of γ-Al2O3 Nanoparticles Using Conductive Polyaniline Doped by Dodecylbenzene Sulfonic Acid.

In this study, electrically conductive PANDB/γ-Al2O3 core–shell nanocomposites were synthesized by surface modification of γ-Al2O3 nanoparticles using polyaniline doped with dodecylbenzene sulfonic acid. The PANDB/γ-Al2O3 core–shell nanocomposites were synthesized by in situ polymerization. Pure PANDB and the PANDB/γ-Al2O3 core–shell nanocomposites were characterized using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, and measurement of a four-point probe. The conductivity of the PANDB/γ-Al2O3 core–shell nanocomposite was about 0.72 S/cm when the weight ratio of aniline/γ-Al2O3 was 3/1. The results showed that the conductivity of the PANDB/γ-Al2O3 core–shell nanocomposite decreased with increasing amounts of γ-Al2O3 nanoparticles. The transmission electron microscopy results indicated that the γ-Al2O3 nanoparticles were thoroughly coated with PANDB to form a core–shell structure. Transmission electron microscopy and field emission scanning electron microscopy images of the conductive PANDB/γ-Al2O3 core–shell nanocomposites also showed that the thickness of the PANDB layer decreased as the amount of γ-Al2O3 was increased.

Effect of a nanoparticle on wettability alteration and wettability retainment of carbonate reservoirs

The oil recovery in many carbonate reservoirs is low due to oil-wetness and heterogeneity. In this study, nanoparticles are evaluated for altering the wettability of oil-wet limestones and their properties are compared with those of an anionic surfactant. A surface-modified silica nanoparticle (SiNP) with a negative zeta potential was found to be aqueous stable in brines. Wettability studies showed that the SiNP cannot change the wettability of an initially oil-wet calcite plate, but SiNP treated calcite surface can remain water-wet after aging in oil. Spontaneous imbibition tests confirmed the observations of wettability tests and showed that a SiNP treated carbonate core retained its water-wettability during oil injection and aging. The imbibition into a SiNP treated and oil aged core was comparable to that in a water-wet core. However, SiNP was not able to remove the oil layers in initially oil-wet cores and imbibe water into these cores. In contrast, the anionic surfactant could alter the oil-wet carbonate rocks to a more water-wet condition, but failed to prevent the water-wet surface from getting oil-wet during oil-aging. The results suggest that the SiNP can be injected into wettability-altered (water-wet) reservoirs/regions to help retain the water-wettability during the long-term oil production. The 0.5 wt% SiNP dispersions transported through 18 mD limestone cores without any plugging. The SiNP retention was measured to be 2.5 mg/m2, much higher than that of the anionic surfactant.

Significantly enhancing electro-actuation performance of dielectric elastomer with ZrO2 nanoparticles

Dielectric elastomer is a kind of attractive artificial muscle with fast and reversible deformation excited by applied voltages. Typical dielectric elastomers suffer from low dielectric breakdown strength, which limits the achievable electro-actuation performance. We report that the introduction of surface-modified ZrO2 nanoparticles in dielectric elastomer (poly(styrene-b-butyl acrylate-b-styrene)) can significantly increase the dielectric breakdown strength. We highlight that the surface modifier molecules for ZrO2 nanoparticles should be designed to have an oligomeric chain compatible with the elastomer matrix to relieve the entropy loss of the elastomer chains. Thus, good dispersion of the nanoparticles can be achieved and the modulus is mildly increased. As a result, the maximum electro-actuation area strain is increased by a factor of 2.0 (from 19.1% to 37.8%), and the maximum energy density by a factor of 9.2 (from 5.96 kJ/m3 to 55.15 kJ/m3) by adding 1.7 vol% ZrO2 of 8 nm.

Dual-Approach Electrochemical Surface-Enhanced Raman Scattering Detection of Mycobacterium tuberculosis in Patient-Derived Biological Specimens: Proof of Concept for a Generalizable Method to Detect and Identify Bacterial Pathogens.

The recent surge in infectious disease-causing pathogens, resulting in global catastrophe, has merited a pivotal quest toward point-of-care (POC) diagnostics. Mycobacterium tuberculosis (MTB) is still the top bacterium-based infectious disease-causing pathogen worldwide. In a concerted effort toward simplifying and decentralizing the discriminatory screening of MTB causing pathogens, electrochemical surface-enhanced Raman scattering (EC-SERS) was adopted to create a customized screening tool. The development strategy combined five key factors, including (i) a simplified Tollens'-based chemical synthesis method for bulk supply of silver nanoparticles, (ii) the deliberate surface modification of nanoparticles with carefully selected polyelectrolytes to resemble the conditioning layer usually found on a natural substratum, (iii) uniform SERS-active films formed through simple unprogrammed assembly, (iv) the controlled manipulation of the local electric field through applied voltage using a technique that does not conform to the limitations of classical EC-SERS, and (v) the inherent specificity of the target-specific SERS vibrational signature. The EC-SERS platform was able to discriminatively detect and identify TB-derived mycobacteria, including three clinically relevant MTB strains, TB-H37Rv, TB-HN878, and TB-CDC1551. Moreover, a customized voltage stepping protocol, compatible with either the inclusion of a short preincubation step or with in situ EC-SERS is illustrated. From the obtained SERS vibrational signatures, a band indicating a mode unique to TB-derived/TB-affiliated mycobacteria and thus not observed for other bacterial types used in this study was illustrated. Furthermore, provisional investigation, done as prelude for assessing the potential for translational adaptability of the EC-SERS technique toward POC clinical settings for sputum and urine specimens, was carried out.

Glimpse into the Cellular Internalization and Intracellular Trafficking of Lipid- Based Nanoparticles in Cancer Cells.

Lipid-based nanoparticles, as drug delivery carriers, are commonly used for the delivery of anti-cancer therapeutic agents. Due to their smaller particle size and similarity to cell membranes, Lipid-based nanoparticles are readily internalized into cancer cells. Cancer cells also overexpress receptors for specific ligands, including folic acid, hyaluronic acid, and transferrin, on their surface, thus, allowing the use of their ligands for surface modification of the lipid-based nanoparticles for their specific recognition by receptors on cancer cells. This would also allow the gradual intracellular accumulation of the targeted functionalized nanoplatforms. These ligand-receptor interactions eventually enhance the internalization of desired drugs by increasing the nanoplatforms cellular uptake. The cellular internalization of the nanoplatforms varies and depends on their physicochemical properties, including particle size, zeta potential, and shape. The cellular uptake is also influenced by the types of ligand internalization pathways utilized by cells, such as phagocytosis, macropinocytosis, and multiple endocytosis pathways. This review classifies and discusses lipidbased nanoparticles engineered to carry specific ligands, their recognition by receptors on cancer cells, and their cellular internalization pathways. Moreover, the intracellular fate of nanoparticles decorated with specific ligands and their best internalization pathway (caveolae-mediated endocytosis) for safe cargo delivery are also discussed.