Electrophoretic Light Scattering Research Articles

Synthesis and characterization of new surface modified magnetic nanoparticles and application for the extraction of letrozole from human plasma and analysis with HPLC-fluorescence

Acetic acid-functionalized magnetic nanoparticles modified by (3-amino-propyl)-tri-ethoxy silane was synthesized and used as a new solid-phases adsorbent. Infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy (EDX), vibrating sample magnetometer (VSM) and Electrophoretic Light Scattering (ELS) were used to characterize the modified nanoparticles. The molecular interaction between letrozole and nanoparticles (NPs) was studied using density functional theory (DFT) calculations. The developed nanoparticles were applied for dispersive solid-phase extraction of letrozole (an anticancer drug) from human plasma. Extracted letrozole was quantified using an isocratic HPLC/FL method. The extraction efficiency was optimized using one experiment at a time optimization method based on the adsorbent quantity, sample pH, adsorption time, desorption time, and elution solvent type/volume. The analysis method was fully validated according to the FDA guideline for bioanalytical method validation. The linear quantification range was 0.01−1 μg/mL and the lower limit of quantification (LLOQ) was 0.01 μg/mL. Plasma samples of 6 patients were analyzed and the measured letrozole concentrations range was 0.04−0.31 μg/mL. The newly synthesized magnetic nanoparticles were used successfully for the extraction of letrozole from spiked and clinical plasma samples. The developed method is a precise and simple method that is suitable for pharmacokinetic studies and clinical applications.

Binary ionic iron(III) porphyrin nanostructured materials with catalase-like activity

Supramolecular structures were prepared in water by ionic self-assembly of oppositely charged iron(III) porphyrins and tested as a new class of catalase mimics. Iron(III) porphyrins carrying the positively charged groups, N-methyl-4-pyridinium (FeTMPyP), 4-pyridinium (FeTHPyP) and tetrafluoro-4-imidazoliumphenyl (FeTFHImP) were assembled with iron tetrakis(4-sulfonatophenyl)porphyrin (FeTSPP), at an optimized pH. The material with the best catalase activity (FeTHPyP:FeTSPP) showed 65-77 catalase units (U)/mg in the pH range 3.5-7.0, which was significantly higher than the 3 U/mg observed for the individual porphyrins. Analogous metal-free structures had no catalytic activity. Micro-scale structures with nanoscale features were observed by Scanning Electron Microscopy. Studies of the chemical composition of materials by X-ray Photoelectron Spectroscopy showed the formation of structures with a 1:1 ratio for (+):(‒) tectons. Characterization of particles in solution was carried out at different pH and before and after catalysis by UV-vis spectroscopy, Dynamic Light Scattering (measurement of hydrodynamic diameters) and Electrophoretic Light Scattering (measurement of zeta potentials).

Effect of surface acidity of SiO2 nanoparticles on thermal stability of polymer solutions for application in EOR processes

This study has a primary objective the evaluation of the effect of surface acidity of silica nanoparticles for mitigation of time-dependent thermal degradation of polymer solutions of partially hydrolyzed polyacrylamide (HPAM), for employment in chemical enhanced oil recovery (EOR) processes. For this, silica (SiO2) nanoparticles were modified on the surface with NaOH (SiO2B) and HCl (SiO2A). The obtained nanoparticles were characterized through field emission electron microscopy, surface area, total acidity by NH3-Temperature programmed desorption, dynamic light scattering (DLS), and electrophoretic light scattering (ELS) for zeta potential. The nanoparticle-polymer interaction was analyzed by adsorption isotherms. Also, the rheological behavior of HPAM solutions at 500 mg L−1 with and without 3000 mg L−1 of raw and functionalized nanoparticles was evaluated at a temperature of 70 °C through steady-state rheometry and dynamic oscillatory measurements at the day zero and after 15 days of aging. Also, coreflooding tests were carried out at conditions of pressure and temperature of a reservoir of interest using the aged polymer solutions with and without nanoparticles. The results show that the polymer adsorption decreases in the order SiO2B > SiO2>SiO2A, indicating that polymer uptake is higher as the surface acidity of nanoparticles decreases. SiO2B nanoparticles showed greater interactions between the functional groups on the surface and the HPAM in solution, forming a polymer network more resistant to degradation. A lower viscosity reduction with the addition of the unmodified SiO2 nanoparticles and SiO2B up to 49.6% and 22.9% was observed, respectively, and is closely related to the adsorption affinity and nanoparticles’ surface acidity. Coreflooding tests also indicated that, there is lower polymer retention in the porous medium when nanoparticles are included. In addition, the aged polymer solution with nanoparticles promotes an additional oil recovery of about 30% regarding polymer without nanoparticles.

Determination of Protein Charge in Aqueous Solution Using Electrophoretic Light Scattering: A Critical Investigation of the Theoretical Fundamentals and Experimental Methodologies.

Studies are reported of the measurement of electrophoretic mobilities of bovine serum albumin (BSA) in aqueous potassium chloride solutions as a function of ionic strength and pH using electrophoretic light scattering (ELS). It is demonstrated that the use of palladium or platinum electrodes should be avoided and that platinized platinum electrodes are necessary to avoid interference from unwanted electrochemical phenomena at the electrode-liquid interface. Potentiometric acid titration was performed to quantify the amount of protonic charge per protein molecule at the same pH values as the electrophoretic mobility measurements. It is shown that appropriate selection of an electrokinetic model yields excellent agreement between predicted and experimental electrophoretic mobilities across the ranges of pH and ionic strength studied in accordance with the protonic charge values obtained by titration. The experimental results are explained in terms of protonation, chloride counterion binding, and protein molecule permeability. This work highlights specific requirements of using ELS for confident analysis of proteins in aqueous solutions.

Personalized Graphene Oxide-Protein Corona in the Human Plasma of Pancreatic Cancer Patients.

The protein corona (PC) that forms around nanomaterials upon exposure to human biofluids (e.g., serum, plasma, cerebral spinal fluid etc.) is personalized, i.e., it depends on alterations of the human proteome as those occurring in several cancer types. This may relevant for early cancer detection when changes in concentration of typical biomarkers are often too low to be detected by blood tests. Among nanomaterials under development for in vitro diagnostic (IVD) testing, Graphene Oxide (GO) is regarded as one of the most promising ones due to its intrinsic properties and peculiar behavior in biological environments. While recent studies have explored the binding of single proteins to GO nanoflakes, unexplored variables (e.g., GO lateral size and protein concentration) leading to formation of GO-PC in human plasma (HP) have only marginally addressed so far. In this work, we studied the PC that forms around GO nanoflakes of different lateral sizes (100, 300, and 750 nm) upon exposure to HP at several dilution factors which extend over three orders of magnitude from 1 (i.e., undiluted HP) to 103. HP was collected from 20 subjects, half of them being healthy donors and half of them diagnosed with pancreatic ductal adenocarcinoma (PDAC) a lethal malignancy with poor prognosis and very low 5-year survival rate after diagnosis. By dynamic light scattering (DLS), electrophoretic light scattering (ELS), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and nano liquid chromatography tandem mass spectrometry (nano-LC MS/MS) experiments we show that the lateral size of GO has a minor impact, if any, on PC composition. On the other side, protein concentration strongly affects PC of GO nanoflakes. In particular, we were able to set dilution factor of HP in a way that maximizes the personalization of PC, i.e., the alteration in the protein profile of GO nanoflakes between cancer vs. non-cancer patients. We believe that this study shall contribute to a deeper understanding of the interactions among GO and HP, thus paving the way for the development of IVD tools to be used at every step of the patient pathway, from prognosis, screening, diagnosis to monitoring the progression of disease.

Implementation of High Gas Barrier Laminated Films Based on Cellulose Nanocrystals for Food Flexible Packaging

In this work, three types of cellulose nanocrystals (CNCs) were used: CNCSO3H extracted from wood pulp by sulfuric acid (H2SO4), CNCCOOH extracted from cotton linters by ammonium persulfate (APS) and CNCCOOR obtained by esterification of the previous two CNCCOOH and CNCSO3H. For a comparative assessment of gas barrier performance, plastic films such as PLA, PET, PE, PP, OPP and OPA were selected, coated with the three types of CNCs and finally laminated with a solvent-based polyurethanic adhesive. First, all dispersed CNCs were characterized by apparent hydrodynamic diameter and Z potential by means of dynamic light scattering (DLS) and electrophoretic light scattering (ELS) techniques, respectively, followed by the crystallinity index (XRD), thermogravimetric analysis (TGA) and evaluation of Fourier-transform infrared spectroscopy (FTIR), as well as the charges density. The surface chemistry of coated plastics (CNCs-P) was assessed by the Z potential through the electrokinetic technique (streaming potential method) and the optical contact angle (OCA). Lastly, laminated films (P-CNC-P) were evaluated by gas permeability measurements at 23 °C and 50–80% RH. It is worth noting that improvements between 90% and 100% of oxygen barrier were achieved after the lamination. This paper provides insights on the choice of cellulosic nanomaterials for the design and development of advanced and sustainable food packaging materials.

Optimisation of Dyes@SWCNT Raman Nanoprobes

Single-Walled Carbon Nanotubes (SCWNTs) have attracted a lot of attention in biomedical fields. Their easily functionalised surface and ability to encapsulate different materials make them interesting not only for imaging, but also for other applications, such as drug delivery and cell targeting. This work concerns specifically the use of SWCNTs to fabricate Raman nanoprobes for bio-imaging. These nanoprobes are composed of dyes encapsulated inside the SWCNTs and the nanotubes are grafted with anti-bodies functionalized on the outer surface.First, we aim to optimize the encapsulation process so that the dye/SWCNTs nanohybrid gives a strong, uniform and reproductible signal that is easily detectable by Raman imaging. This is done by varying the parameters of the liquid-phase encapsulation process and crosschecking the results by Raman imaging. We also work to optimize the stability of the nanohybrid in biological media. This parameter is important to determine the best conditions for antibody attachment and cell/tissue interactions. Using different biological buffers, we study the dispersion of the assemblies with Dynamic Light Scattering (DLS) and their stability with Electrophoretic Light Scattering (ELS). The results of the analysis on the nanohybrids show an average hydrodynamic radius of 160 nm and a Zeta potential at -45 mV in aqueous media, proving that the stability of the short nanohybrids in water is favourable to the development of nanoprobes.

Calcium phosphate formation on TiO2 nanomaterials of different dimensionality

Calcium phosphates (CaPs) composites with different TiO2 nanomaterials (TiNMs) have recently attracted attention due to their potential application as implant materials for hard tissue regeneration. Among different synthetic routes for such composites, biomimetic synthesis attracts special attention as a green synthesis route. To rationalize biomimetic synthesis, the influence of surface structure and surface charge density of different TiNMs on CaPs precipitation should be determined. In this paper, for the first time, the influence of TiO2 nanoparticles (TiNPs) and titanate nanotubes (TiNTs) on CaPs spontaneous precipitation was investigated. In addition, the ability of TiNMs to induce CaPs formation in corrected simulated body fluid (c-SBF) was tested. The advancement of the CaPs precipitation was followed by potentiometric measurements, while the obtained materials were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS), powder X-ray diffraction (PXRD), scanning (SEM) and transmission (TEM) electron microscopy, electron paramagnetic resonance spectroscopy (EPR), Brunauer-Emmett-Teller surface area analysis (BET), dynamic (DLS) and electrophoretic light scattering (ELS), atomic force microscopy (AFM) and thermogravimetric (TGA) analysis. Both TiNMs showed poor ability to promote CaPs formation in c-SBF which can be attributed to their low absolute zeta-potential value. However, during spontaneous precipitation, they exhibited uncommon dual influence on precipitation kinetics, i.e. inhibition of initially formed amorphous calcium phosphate (ACP) transformation at lower and promotion at higher concentrations. After one hour of reaction time, in the presence of both TiNMs, calcium deficient hydroxyapatite was formed (CaDHA). Morphology of the CaDHA depended on the type and concentration of TiNMs. However, PXRD, EPR and TGA characterization confirmed that there is no significant difference between CaDHA formed in the presence of different TiNMs, which indicates that CaDHA composites with different TiNMs could be prepared at similar conditions. In addition, they can be prepared in a much shorter time compared to the usual procedure with SBF. Obtained results confirm the importance of surface structure and charge in CaPs – TiNMs interactions. They as well contribute to a deeper insight into precipitation processes on the nanosurfaces, which enables a rational approach not only in the biomimetic synthesis of novel biocomposites for hard tissue regeneration but also of composites for other applications.

Synthesis of silver nanoparticles in context of their cytotoxicity, antibacterial activities, skin penetration and application in skincare products

ABSTRACT The benefits of silver nanoparticles (AgNPs) have been known in many fields from catalysis through optics to medicine due to their unique size-dependent properties. Recently, there is also a growing interest in novel skincare formulations containing AgNPs. In this work, AgNPs were successfully synthesised and were characterised by UV-Vis spectroscopy and Transmission Electron Microscopy (TEM). In addition, an analysis of particle size distribution (measured by Dynamic Light Scattering – DLS) and zeta potential (using the method Electrophoretic Light Scattering – ELS) were made. The obtained AgNPs were in two sizes: small (20 nm ± 5 nm) and large (100 nm ± 5 nm). The assessment of the cytotoxic effect on human skin cells was done. Smaller AgNPs showed less cytotoxicity and thus greater safety for skin, so they were introduced into new skincare formulations such as oil/water (O/W) emulsion, water/oil (W/O) emulsion and hydrogel. Moreover, the study of release AgNPs from emulsions and hydrogel using Franz diffusion chamber with pig skin as a membrane has been conducted. The receptor fluid measurements were performed by Atomic Absorption Spectroscopy (AAS). The last point of the research was the performance of microbiological tests to determine the antibacterial effect of the smaller AgNPs in both solution and cosmetic.

Sucupira Oil-Loaded Nanostructured Lipid Carriers (NLC): Lipid Screening, Factorial Design, Release Profile, and Cytotoxicity.

Essential oils are odorant liquid oily products consisting of a complex mixture of volatile compounds obtained from a plant raw material. They have been increasingly proven to act as potential natural agents in the treatment of several human conditions, including diabetes mellitus (DM). DM is a metabolic disorder characterized by chronic hyperglycemia closely related to carbohydrate, protein and fat metabolism disturbances. In order to explore novel approaches for the management of DM our group proposes the encapsulation of sucupira essential oil, obtained from the fruits of the Brazilian plants of the genus Pterodon, in nanostructured lipid carriers (NLCs), a second generation of lipid nanoparticles which act as new controlled drug delivery system (DDS). Encapsulation was performed by hot high-pressure homogenization (HPH) technique and the samples were then analyzed by dynamic light scattering (DLS) for mean average size and polydispersity index (PI) and by electrophoretic light scattering (ELS) for zeta potential (ZP), immediately after production and after 24 h of storage at 4 °C. An optimal sucupira-loaded NLC was found to consist of 0.5% (m/V) sucupira oil, 4.5% (m/V) of Kollivax® GMS II and 1.425% (m/V) of TPGS (formulation no. 6) characterized by a mean particle size ranging from 148.1 ± 0.9815 nm (0 h) to 159.3 ± 9.539 nm (at 24 h), a PI from 0.274 ± 0.029 (0 h) to 0.305 ± 0.028 (24 h) and a ZP from −0.00236 ± 0.147 mV (at 0 h) to 0.125 ± 0.162 (at 24 h). The encapsulation efficiency and loading capacity were 99.98% and 9.6%, respectively. The optimized formulation followed a modified release profile fitting the first order kinetics, over a period of 8 h. In vitro cytotoxicity studies were performed against Caco-2 cell lines, for which the cell viability above 90% confirmed the non-cytotoxic profile of both blank and sucupira oil-loaded NLC.

Fast Production of Cellulose Nanocrystals by Hydrolytic-Oxidative Microwave-Assisted Treatment.

In contrast to conventional approaches, which are considered to be energy- and time-intensive, expensive, and not green, herein, we report an alternative microwave-assisted ammonium persulfate (APS) method for cellulose nanocrystals (CNCs) production, under pressurized conditions in a closed reaction system. The aim was to optimize the hydrolytic-oxidative patented procedure (US 8,900,706), replacing the conventional heating with a faster process that would allow the industrial scale production of the nanomaterial and make it more appealing to a green economy. A microwave-assisted process was performed according to different time–temperature programs, varying the ramp (from 5 to 40 min) and the hold heating time (from 60 to 90 min), at a fixed reagent concentration and weight ratio of the raw material/APS solution. Differences in composition, structure, and morphology of the nanocrystals, arising from traditional and microwave methods, were studied by several techniques (TEM, Fourier transform infrared spectroscopy (FTIR)-attenuated total reflectance (ATR), dynamic light scattering (DLS), electrophoretic light scattering (ELS), thermogravimetric analysis (TGA), X-ray diffraction (XRD)), and the extraction yields were calculated. Fine tuning the microwave treatment variables, it was possible to realize a simple, cost-effective way for faster materials’ preparation, which allowed achieving high-quality CNCs, with a defined hydrodynamic diameter (150 nm) and zeta potential (−0.040 V), comparable to those obtained using conventional heating, in only 90 min instead of 16 h.

Preparation and characterization of dithiocarbazate Schiff base–loaded poly(lactic acid) nanoparticles and analytical validation for drug quantification

Dithiocarbazate Schiff bases have been reported as a class of compounds that exhibit a wide range of pharmacological activities against neglected diseases such as malaria, trypanosomiasis, and tuberculosis. This work reports the encapsulation of the 1-(S-benzyldithiocarbazate)-3-methyl-5-phenyl-pyrazole (DTC) into biodegradable polymeric nanoparticles (NPs) of poly(lactic acid) (PLA) aiming potential drug delivery application. The DTC-loaded PLA-NPs were prepared by the single-nanoemulsification method using the poly(vinyl alcohol) (PVA) as a surfactant. The nanostructured system was characterized mainly by dynamic light scattering (DLS), electrophoretic light scattering (ELS), and transmission electron microscopy (TEM). The NPs show good colloidal stability exhibiting mean hydrodynamic diameter 157 ± 5 nm and zeta potential − 36 ± 3 mV. The encapsulation efficiency and drug loading were 52 ± 14% and 4.8 ± 1.5%, respectively. The quantifications of DTC and residual PVA in the NPs were performed by UV-Vis absorption spectroscopy. The analytical methods were validated according to regulatory agencies. Both quantification analytical curves showed good precision, in repeatability (intra-day) and intermediate (inter-day), and also good accuracy with low values of detection and quantification. The new nanostructured system, DTC-loaded PLA-NPs, shows advantages to improve stability and to overcome water solubility problems of the dithiocarbazate Schiff bases aiming potential drug delivery applications.

Core‐crosslinking as a pathway to develop inherently antibacterial polymeric micelles

ABSTRACTPositively charged polymeric materials have been an alternative to combat bacteria as they exhibit inherently antibacterial potency via bacteria membrane disruption. In this study, we report facile preparation of positively charged core‐crosslinked polymeric micelles with inherent antibacterial properties. Spherical micelles were prepared by self‐assembling of poly(4‐vinylpyridine)‐b‐(oligoethylene glycol methyl ether methacrylate) copolymer in aqueous solution. Herein, quaternization reaction was utilized for the first time to core crosslink the micelles through the pyridine rings utilizing their hydrophobic core and thus resulting positively charged nanostructures. Dynamic light scattering (DLS) results identified that the micelles have an average hydrodynamic diameter of 114 nm with a polydispersity index ranging between 0.105 and 0.114. The electrophoretic light scattering (ELS) measurements demonstrated that the micelles have zeta potential values ranging from +38 to +63 mV. It was evident from both ELS and DLS results that the micelles in solution exhibit long‐term stability as the samples were able to maintain their size and charge even after a year of storage. Further, the micelles exhibited inherently antibacterial activity against Escherichia coli and furthermore, this antibacterial efficacy was sustained over a period of 1 year. These stable core‐crosslinked micelles are proposed to have great potential as antibacterial materials for long‐term applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48393.

Synthesis and Characterization of Bacterial Nanocellulose from Banana Peel for Water Filtration Membrane Application

This research reports the result obtained from the synthesis and characterization of Bacterial Nano Cellulose (BNC) from Nangka banana peel (Musa sp L.) media for water filtration membrane application. The BNC synthesis is successfully achieved under the condition of banana peel and water ratio of 1:3, bacterial nutrition : Glucose 10% (w/v), Ammonium Sulphate (NH4)2SO4 1% (w/v), pH: 4, and amount of starter: 15% (w/v). The duration of fermentation is 7 days. The water content obtained in BNC banana peel is 86,59%. The Scanning Electron Microscopy (SEM) analysis shows the resulting nanocellulose is nanofibril 30-50 nm in diameter. The X ray diffraction (XRD) shows the banana peel BNC crystallinity index (Ic) is 86,94% and cellulose Type I. The Fourier Transform Infra-Red (FTIR) spectra confirms the bond and functional group of nanocellulose. These results support the required properties for strong but flexible membrane filter. The potential zeta absolute value -11.39 mV from the Electrophoretic Light Scattering (ELS) shows that BNC colloidal solution has good stability that it can be further used for the manufacture of water filter catalytic membrane composites.

Surface active fatty acid ILs: Influence of the hydrophobic tail and/or the imidazolium hydroxyl functionalization on aggregates formation

Nine structurally-related fatty acid ionic liquids have been prepared and their thermal behavior as well as their ability to self-assemble in water has been investigated. The thermal properties were studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), while the aggregation behavior was analyzed by tensiometry, isothermal titration calorimetry (ITC), conductometry, dynamic light scattering (DLS), and electrophoretic light scattering (ELS). Structural variations concerned both the imidazolium cation (presence or not of hydroxyl groups) and the anion (length of the fatty acid), and affected in different ways the ILs' properties.With regards to the thermal stability, the presence of the hydroxyl group on the cation had a beneficial effect on stability regardless of the anion's length. This latter played instead a major role in allowing the solubility of the ILs in water (C18-stearate ILs were not soluble in water) and in determining the critical micelle concentration (CMC) values, as the reduction of the anion length in moving from C16-palmitate to C14-myristate anions disfavors aggregates formation.Several other parameters characterizing the adsorption of fatty acid ILs at the air/water interface, some thermodynamic parameters of the aggregation process as well as size distribution and stability of the aggregates were also determined.

Interaction between Copper Oxide Nanoparticles and Amino Acids: Influence on the Antibacterial Activity.

The increasing concern about antibiotic-resistance has led to the search for alternative antimicrobial agents. In this effort, different metal oxide nanomaterials are currently under investigation, in order to assess their effectiveness, safety and mode of action. This study focused on CuO nanoparticles (CuO NPs) and was aimed at evaluating how the properties and the antimicrobial activity of these nanomaterials may be affected by the interaction with ligands present in biological and environmental media. Ligands can attach to the surface of particles and/or contribute to their dissolution through ligand-assisted ion release and the formation of complexes with copper ions. Eight natural amino acids (L-Arg, L-Asp, L-Glu, L-Cys, L-Val, L-Leu, L-Phe, L-Tyr) were chosen as model molecules to investigate these interactions and the toxicity of the obtained materials against the Gram-positive bacterium Staphylococcus epidermidis ATCC 35984. A different behavior from pristine CuO NPs was observed, depending on the aminoacidic side chain. These results were supported by physico-chemical and colloidal characterization carried out by means of Fourier-Transform Infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and light scattering techniques (Dynamic Light Scattering (DLS), Electrophoretic Light Scattering (ELS) and Centrifugal Separation Analysis (CSA).

Novel nanosized AS1411-chitosan-BODIPY conjugate for molecular fluorescent imaging.

Background: In recent years, non-invasive imaging technologies for early cancer detection have drawn worldwide attention. In this study, an antinucleolin aptamer, AS1411, was successfully conjugated to BODIPY-labeled chitosan and studied on T47D and HEK-293 cell lines.Methods: After conjugation of the aptamer to chitosan nanoparticles and purification, its structure was confirmed using atomic force microscopy (AFM), electrophoretic light scattering (ELS) and dynamic light scattering (DLS). Results of AFM, DLS and ELS of both conjugation and chitosan were compared for confirmation of conjugation. Conjugates were mixed with BODIPY FL fluorescent dye, purified and lyophilized. The labeled conjugate was characterized using Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, ELS and DLS. In vitro cellular uptake and cytotoxic effects of BODIPY-labeled chitosan–AS1411 aptamer conjugates were evaluated using the XTT assay on T47D and HEK-293 cells and flow cytometry on T47D cells.Results: The data showed that uptake of BODIPY-labeled chitosan–AS1411 aptamer conjugate was satisfactory. Moreover, there was no statistically significant cytotoxicity of the conjugate on either cell line.Conclusion: The outcomes confirmed the potential application of this new targeted imaging agent as a novel cancer diagnostic agent for molecular imaging.

Interaction between gold nanoparticles and blood proteins to define disease states

Introduction: Gold Nanoparticles (AuNPs) have been used for several drug delivery applications with promising results, although a detailed model for interaction between AuNPs and biomolecules present in the bloodstream is still lacking [1,2]. Furthermore, some diseases alter the serum protein content profile, influencing the composition of adsorbed proteins at the AuNP surface, the so-called protein corona, indicating a possibility for future diagnostic tools [3]. In this work, we study the interaction between blood proteins, such as Albumin (a globular protein with 66 kDa) and Fibrinogen (Fib), a cylindrically-shaped protein with 340 kDa), with AuNPs, in order to improve our understanding of this interaction on a complex protein mixture such as Human Serum. Data from individual proteins can hopefully be used to model AuNP-plasma proteins interaction, as the basis for future studies and applications of AuNPs in the diagnosis of important diseases and in vivo treatment. Materials and methods: Spherical AuNPs with a diameter of ca. 15 nm were chemically synthesized, functionalized with an alkanethiol (11-MUA) to increase their colloidal stability, and further conjugated by simple incubation with Bovine Serum Albumin (BSA) or bovine Fib, used as homologs of their human counterparts. The protein corona was analyzed by Agarose Gel Electrophoresis (AGE), SDS-PAGE, Dynamic Light Scattering (DLS) and Nanoparticle Tracking Analysis (NTA). Zeta-potential values were estimated by Ferguson Plot Analysis of the AGE runs or were determined by Electrophoretic Light Scattering (ELS). Computational methods were applied to the analysis of electrophoretic mobility as observed in video sampling of the AGE runs. Results: Size and concentration of the synthesized AuNPs was determined by UV-vis spectroscopy. rom a Langmuir Isotherm fitting of the observed bioconjugation curves, binding constants were obtained for AuNP-MUA conjugation with BSA (1.5 × 10−2 ± 0.1), or Fib (34.3 × 10−2 ± 1.2); and for AuNP-CALNN conjugation with Fib (51.2 × 10−2 ± 4.7). AuNP-CALNN conjugation with BSA lead to band smearing on AGE, not allowing an evaluation of the binding process. Overnight competitive incubation of a protein mixture with AuNP-MUA, favoured Fib adsorption over BSA. Discussion and conclusions: Electrostatic protein conjugates show a robust structure in AGE runs, with generally low band dispersion, especially for AuNP-MUA conjugates. Video analysis revealed protein corona stabilization and a constant band migration velocity. Binding affinity constants and competitive behaviour confirmed a higher affinity for Fib conjugation over BSA to the functionalized AuNPs. This higher binding affinity for Fib can be explained by its higher surface contact area and a possible cooperativity mechanism, deserving further analysis.

Zinc Porphyrin-Functionalized Fullerenes for the Sensitization of Titania as a Visible-Light Active Photocatalyst: River Waters and Wastewaters Remediation.

Zinc porphyrin-functionalized fullerene [C60] derivatives have been synthesized and used to prepare titania-based composites. The electrochemical properties and HOMO and LUMO levels of the photosensitizers were determined by electrochemical measurements. Raman and IR techniques were used to study chemical groups present on the titania surface. Absorption properties of the composites were measured in the solid state by diffuse reflectance UV-Vis spectra (DRS). The zeta potential and aggregate sizes were determined using dynamic light scattering (DLS) and electrophoretic light scattering (ELS) techniques. Surface areas were estimated based on Brunauer–Emmett–Teller (BET) isotherms. The photocatalytic activity of the photocatalysts was tested using two model pollutants, phenol and methylene blue. The composite with the highest photocatalytic potential (1/TiO2) was used for river and wastewater remediation. The photodegradation intermediates were identified by LC-UV/Vis-MS/MS techniques.

Encapsulation of Albumin in Organic Nanotube Channel: Structural Investigation by Small-Angle X-ray Scattering.

Rationally designed bolaamphiphiles are known to self-assemble into nanotube structures. Herein, we report the formation of an inclusion complex between a nanotube and bovine serum albumin (BSA). This complex formation was confirmed by ultraviolet (UV) absorbance and electrophoretic light scattering (ELS). The structure for different mixing ratios of BSA to the nanotube was also investigated by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The structural analysis with our proposed model has revealed that the BSA molecules were contained within the internal space of the nanotube with maintenance of its tubular structure.