Dynamic Light Scattering Results Research Articles

Evaluation Avocado Soybean Unsaponifiables Loaded in Poly (lactic-co-glycolic) Acid/Avocado Soybean Unsaponifiables-Fibrin Nanoparticles Scaffold (New Delivery System) is an Effective Factor for Tissue Engineering.

Background:Growth factors and chemical stimulants have key role in cartilage tissue engineering, but these agents have unfavorable effects on cells. Avocado soybean unsaponifiables (ASU) has chondroprotective and anti-inflammatory effects. In this study, fibrin2nanoparticles (FNP)/ASU, as a new delivery system, with stem cells applied for cartilage tissue engineering in poly (lactic-co-glycolic) acid (PLGA) scaffold.Materials and Methods:FNP/ASU prepared by freeze milling and freeze drying. NFP/ASU was characterized by dynamic light scattering (DLS). PLGA-NFP/ASU scaffold was fabricated and assessed by scanning electron microscope (SEM). Human adipose-derived stem cells (hADSCs) were seeded on scaffold and induced for chondrogenesis. After 14 days, cell viability and gene/protein expression evaluated.Results:The results of DLS and SEM indicated that nanoparticles had high quality. The expression of type II collagen and SOX9 and aggrecan (ACAN) genes in differentiated cells in the presence of ASU was significantly increased compared with the control group (P and lt; 0.01), on the other hand, type I collagen expression was significantly decreased and western blot confirmed it.Conclusions:This study indicated FNP/ASU loaded in PLGA scaffold has excellent effect on chondrogenic differentiation of hADSCs and tissue engineering.

Synthesis, Characterization, and Cytotoxicity Evaluation of Polyethylene Glycol-Coated Iron Oxide Nanoparticles for Radiotherapy Application

Background:Treatment methods for cancer that are widely being utilized affect both normal and cancerous cells. We report synthesis polyethylene glycol (PEG)-coated Fe3O4 nanoparticles (NPs) and its characteristic properties and appraise its potential as a promising radiation sensitizer candidate in radiotherapy that improves cancer treatment and reduces side effects of radiation.Materials and methods:PEG-coated Fe3O4 NPs were synthesized by chemical coprecipitation method and characterized by studying their size, structure, functional group, stability, magnetization, and cytotoxicity using different techniques. X-ray powder diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis results show that Fe3O4 NPs have been functionalized with PEG molecules during the course of synthesis.ResultsSynthesized NPs have good stability based on zeta-potential study. Dynamic light-scattering results reveal that PEG-coated Fe3O4 has a greater hydrodynamic size than bare Fe3O4. Transmission electron microscopy (TEM) micrograph exhibited that NPs are roughly spherical with size in range of 10–20 nm. Saturation magnetization value of PEG-coated and bare Fe3O4 also confirms coating and shows superparamagnetic behavior. Cytotoxicity evaluation study indicated that PEG-coated Fe3O4 is biocompatible on L929 and toxic on Michigan Cancer Foundation-7 (MCF-7) (breast cancer cells).Conclusion:These characterized properties of PEG-coated Fe3O4 NPs show that it could be used as a potential radiosensitizer candidate in radiotherapy to significantly improve cancer treatment and minimize painful side effects of radiation.

Polymer-Decorated Cellulose Nanocrystals as Environmentally Friendly Additives for Olefin-Based Drilling Fluids.

In this study, we intended to evaluate the performance of olefin-based drilling fluids after addition of cellulose nanocrystal (CNC) derivatives. For this purpose, firstly, cellulose nanocrystals, produced from sulfuric acid hydrolysis of cotton fibers, were functionalized with poly(N-isopropylacrylamide) (PNIPAM) chains via free radicals. The samples were then characterized via Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), confocal microscopy, dynamic light scattering (DLS), and zeta potential measurements in water. The FTIR and NMR spectra exhibited the characteristic signals of CNC and PNIPAM groups, indicating successful grafting. As expected, X-ray diffractograms showed that the crystallinity of CNCs reduces after chemical modification. TGA revealed that the surface-functionalized CNCs present higher thermal stability than pure CNCs. The confocal microscopy, zeta potential, and DLS results were consistent with the behavior of cellulose nanocrystals decorated by a shell of PNIPAM chains. The fluids with a small amount of modified CNCs presented a much lower volume of filtrate after high-temperature and high-pressure (HTHP) filtration tests than the corresponding standard fluid, indicating the applicability of the environmentally friendly particles for olefin-based drilling fluids.

Size-shrinkable and protein kinase Cα-recognizable nanoparticles for deep tumor penetration and cellular internalization

In the present study, the three functions, including enhanced permeability and retention (EPR) effect, deep penetration within tumor, and receptor-mediated endocytosis, were integrated into a single platform in order to improve antitumor efficiency. A novel nanoparticle (dendrigraft poly-L-lysine@glycyrrhetinic acid@cyclohexane dicarboxylic anhydride@doxorubicin@ hyaluronic acid composite) has been successfully developed and was denoted as DGL-GA-CDA-DOX-HA. The transmission electron microscope (TEM), dynamic light scattering (DLS), polymer dispersity index (PDI), fourier transform infrared spectrometer (FTIR), and zeta potentials were used to characterize the physicochemical properties of the nanoparticles. According to the results of TEM and DLS, the DGL-GA-CDA-DOX-HA nanoparticles could be rapidly degraded with a size shrink from 182.5 nm to 47.7 nm by hyaluronidase (HAase) added in the medium. The loading amount of DOX reached 252.03 ± 36.38 mg/g for DGL-GA-CDA-DOX nanoparticles. When the nanoparticles were in a medium with HAase at pH 5.0, the drug quickly released. However, when the nanoparticles were exposed to a medium without HAase at pH 5.0, or a neutral medium containing HAase, drug release slowed down. The modification of GA on nanoparticles significantly enhanced their affinity and cytotoxicity to hepatocellular carcinoma HepG2 cells. The study showed that the penetrability of DGL-GA-CDA-DOX and DGL-GA-CDA DOX-HA nanoparticles pre-degraded by HAase in vitro multicellular tumor spheroids were always better than that of DGL-GA-CDA-DOX-HA nanoparticles untreated by HAase. The imaging in vivo and ex vivo exhibited that DGL-GA-CDA-DOX-HA nanoparticles could preferentially accumulate in the tumor site. Correspondingly, the DGL-GA-CDA-DOX-HA displayed the preferable antitumor efficiency to other experimental groups in H22 tumor-bearing mice, with a tumor inhibition rate of 71.6%. In short, these results suggested that DGL-GA-CDA-DOX-HA nanoparticles could promote therapeutic effects by modulating particle size and GA receptor-mediated endocytosis.

Green synthesis of less toxic Selenium nanoparticles: Their antibacterial, antioxidant and catalytic activity

Introduction and Aim: Biosynthesis of metal nanoparticles is an important branch of nanobiotechnology. In recent years, microbial biosynthesis of nanoparticles is gaining importance due to its simplicity and eco-friendliness.
 Materials and Methods: In this study, Selenium nanoparticles (Se NPs) were synthesized by using the fungi Fusarium sp. isolated from agricultural soil. Mycosynthesized Se NPs were characterized by UV-Vis spectrometer and Dynamic Light Scattering (DLS) analysis. Further biosynthesized Se NPs screened for different biological activities such as antibacterial, antioxidant, hemolysis, cytotoxicity and catalytic activity.
 Results: Synthesis Se NPs was preliminary observed by a color change from pale yellow to orange red color and confirmed by UV peak at 342 nm. The DLS result shows the particles size ranges from 19 to 43 nm.The obtained result showed that the synthesized Se NPs possess good antibacterial activity against human pathogens such as E. coli, Staphylococcus aureus, Salmonella typhi and Klebsiella pneumonia. Further biogenic Se NPs showed less cytotoxicity on yeast cells and slight hemolysis.
 Conclusion: The synthesized Se NPs have good antioxidant property and antibacterial activity with less haemolytic property these properties lead to use of Se NPs in different biomedical applications. This Se NPs Also showed an efficient catalytic activity by degrading hazardous dyes such as methylene blue and bromothymol blue.

A novel FRET probe for determination of fluorescein sodium in aqueous solution: Analytical application for ophthalmic sample

Fluorescent pyrene nanoparticles (PyNPs) were prepared by a reprecipitation method in the presence of sodium dodecyl sulphate (SDS) as a stabilizer. The formation of PyNPs was confirmed by dynamic light scattering (DLS), UV-visible absorption spectroscopy, fluorescence spectroscopy and excited state lifetime measurements. DLS results of PyNPs shows a narrow size distribution with average particle size of 77.4 nm and negative zeta potential. The systematic FRET experiments performed by measuring fluorescence quenching of PyNPs with successive addition of FL-Na analyte exploited the use of PyNPs as nanoprobe for detection of FL-Na in aqueous solution. The fluorescence of PyNPs was quenched by Fl-Na and quenching is in accordance with the Stern-Volmer relation. The distance r between the donor (PyNPs) and acceptor (FL-Na) molecules was obtained according to the fluorescence resonance energy transfer. The fluorescence quenching results were used further to develop an analytical method for estimation of fluorescein sodium from ophthalmic samples available commercially in the market.

SYNTHESIS OF CdS NANOPARTICLES BY CHEMICAL Co-PRECIPITATION METHOD AND ITS COMPARATIVE ANALYSIS OF PARTICLE SIZE VIA STRUCTURAL AND OPTICAL CHARACTERIZATION

CdS is an important wide bandgap chalcogenides most popularly studied for various optoelectronics and biosensing applications. In this study, CdS Nanoparticles (NPs) have been prepared successfully by chemical co-precipitation method, using cadmium acetate and sodium sulphide as precursors. A comparative study of average particle size calculated by Scherrer Plot, Uniform Deformation Model (UDM), Dynamic Light Scattering (DLS) analysis and Brus Model has been done here. The structural and optical behaviour of synthesized samples were investigated via X-ray diffraction (XRD), DLS and UV–Visible Spectroscopy. The XRD spectra of the prepared CdS NPs revealed the crystalline phase having cubic structure. The average particles size has been studied via Debye Scherrer equation and Scherrer Plot. For the theoretical calculations of particle size along with the induced lattice strain, considering the broadening effect of lattice strain, Williamson-Hall analysis was employed. Assuming the lattice strain to be isotropic in nature, UDM was applied for calculation. The particles size distribution profile in terms of volume as well as intensity was recorded using DLS analysis in ethanol medium at room temperature. Besides this, the energy bandgap was obtained by applying Tauc model in the recorded absorption spectra. The obtained value of bandgap was used in Brus model for estimating the average particle size. The obtained comparative results show that the average particle size of the prepared CdS NPs estimated from Scherrer equation, Scherrer plot, UDM plot and Brus model are almost similar and lies in the range of 2-5 nm whereas the results of DLS showed wide variation in the range of 40-600 nm.

Sodium dodecylbenzenesulfonate–based silver nanoparticles and their potent application as antibiofilm, antimicrobial agent, and trace level determination of amlodipine

Herein, we presented the synthesis and application of sodium dodecylbenzenesulfonate–based silver nanoparticles (termed as SDBS-AgNPs). The SDBS reverse micelles (RMs) in ethanol was used as nanoreactor for green AgNPs synthesis. The size, structure, and shape of SDBS-AgNPs were well distinct by UV/visible (UV/Vis), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and atomic force microscopy (AFM) techniques. The SDBS-AgNPs were quite stable even at high temperature (80 °C), salt concentration (up to 300 μM), and wide pH range (2 to 12). Moreover, SDBS-AgNPs were found to be highly sensitive and selective colorimetric sensor for antihypertensive drug amlodipine (AML). The interaction of AML with SDBS-AgNPs resulted as a substantial increase in the absorbance and a prominent blue shift in wavelength from 426 to 400 nm. DLS results were further confirmed that the SDBS-AgNPs break into smaller sized particles. Similarly, FTIR results also verified the SDBS-AgNPs etching–based sensing of AML molecules due to the strong attraction by amine and carbonyl functional groups on the target drug. The proposed sensor exhibited linear response in the range of 0.001–200 μM (R2 = 0.9917) with limit of detection (LOD) and quantification (LOQ) of 0.161 and 0.49 μM, respectively. The probe remained selective against AML, even in the presence of equimolar interfering species (including other drugs and metal ions). Furthermore, findings proposed that the SDBS-AgNPs might be used as effective substitute to minimize infection severity by obstructing the biofilm formation against nosocomial and urinary tract infection (UTI) causing pathogens.

Precise measurement of particle size in colloid system based on the development of multiple-angle dynamic light scattering apparatus

Dynamic light scattering (DLS) is a widely used, non-invasive and in-situ method for particle size measurement. However, the precision of the measurement results is still under discussion. Theoretically, the apparent hydrodynamic diameter measured by DLS varies with scattering angle due to Mie scattering as well as long-distance interaction between particles. In this paper, a multiple-angle dynamic light scattering (MDLS) apparatus is established. After determining the critical concentration at which multiple scattering occurs at different scattering angle, polystyrene latex (PSL) particles sized from 23 to 500 nm diluted with different concentrations are precisely measured at different scattering angles. By introducing special pin-holes, precise alignment design and beam-stops at all scattering angles, the precision of the MDLS apparatus is highly improved. DLS results are strongly angular and concentration dependent, and the trends vary with particle size. DLS results at infinite dilution and zero angle are obtained after extrapolation, which eliminates the effects of long-range interactions and intraparticle interference. The present optical design extends the application validity of this method from nano particle to submicron particle.

Monitoring phase transition behavior of Poly(N-vinylcaprolactam) via nanostructure-based functionalized carbon nanotubes

The ubiquitous behavior of thermoresponsive polymers (TRPs) in terms of their amphiphilicity and reversible behavior towards temperature make them to exhibit wide applications in biomedical science, biosensors and biotechnological fields. The electrical and surface properties of multiwalled carbon nanotubes (MWCNTs) have received immense attention due to their high flexibility to take any shape (tube, circles) to bind with different macromolecular moieties. Nonetheless, TRPs-MWCNTs interactions with variation in temperature are rarely explored. However, the low solubility of carbon nanotubes (CNTs) in molecular solvents limits their utility in biological process. Therefore, functionalization of CNTs was performed to enhance the dispersibility of CNTs in aqueous medium. In this present study, effect of functionalized carbon nanotubes (fCNTs) on the coil to globular conformation of poly (N-vinylcaprolactam) (PVCL) is explored. PVCL exhibits coil to globular transition due to its biocompatible nature with several additive in permissible range of temperature values. To investigate the lower critical solution temperature (LCST) of PVCL in presence of fCNTs, various biophysical techniques such as fluorescence spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were employed. Furthermore, for better understanding of morphological changes of PVCL in fCNTs, Transmission electron microscopy (TEM) was assessed. The DSC and DLS results confirmed that LCST value of PVCL (32.0 °C) has dropped by 2 °C in presence of fCNTs due to hydrophobic interactions of polymer and fCNTs. This exclusive modification in LCST of PVCL will be sensitive in biological applications. We have studied the first time effect of fCNTs on the phase transition behavior of PVCL which will lead to its widespread applications in the field of biomedical sciences such as drug delivery systems.

Preparation of semi-interpenetrating silk fibroin–polyacrylamide nanogels

Silk fibroin (SF) is a promising material for biomedical applications especially in the form of nanogels that combine the advantages of nanotechnology and cross-linking gel-like systems with various superior properties in biological environment. The present study describes the preparation of a semi-interpenetrating (semi-IPN) network using SF and polyacrylamide (PAAm) in the presence of N,N′-methylenebis(acrylamide) (BAAm) as a chemical crosslinker. While the particles were obtained by an inverse microemulsion method, photo-polymerization reactions were performed with Irgacure as an initiator. UV irradiation time and SF concentrations were adjusted to get stable Semi-IPN nanogels with a size smaller than 200 nm. Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses were used for sample characterizations. FT-IR measurements proved both the existence of SF and PAAM in the nanogel structure and also β-sheet formation of SF with methanol treatment. A characteristic peak at 20.0 A° corresponding to the β-sheet crystalline structure of SF was obtained by XRD analysis. In addition to the dialysis purification, smaller particles can be obtained with a size around 100 nm by increasing SF concentration. DLS results were supported by TEM images of nanogels with a spherical shape. The results indicated that optimized conditions are suitable for the development of SF nanogels with potential applications in drug delivery.

Selective Colorimetric Detection of Mn2+ and Cr2+ Ions using Silver Nanoparticles Modified with Sodium Dodecyl Sulfonate and β-Cyclodextrin

The present study was conducted to determine manganese (Mn2+) and chromium (Cr2+) ions in aqueous systems with a simple, rapid, sensitive, selective, and cost-effective colorimetric approach. Sodium dodecyl sulfonate (SDS) and β-cyclodextrin (CD) were used as both stabilizer and surface functionalizing agents for the synthesis of silver nanoparticles (AgNPs). Synthesized AgNPs were characterized by FT-IR spectroscopy, UV-visible spectroscopy, scanning electron microscopy (SEM), and dynamic light scattering (DLS) techniques. The effect of pH on the stability of nanoparticles was investigated. SDS modified silver nanoparticles (SDS-AgNPs) and SDS with β-cyclodextrin modified silver nanoparticles (SDS-CD-AgNPs) demonstrated sensitive and selective colorimetric detection of Mn2+ and Cr2+ ions at ppm level, respectively. The prepared SDS-AgNPs and SDS-CD-AgNPs solution showed a color change visible to the naked eye from yellow to orange upon adding Mn2+ and Cr2+ ions, respectively; however, other metal ions did not induce such a change. In addition, the results of SEM and DLS for both sensors showed the aggregation of nanoparticles after adding Mn2+ or Cr2+. Overall, the results of this study show the successful synthesis of AgNPs, SDS-AgNPs, and SDS-CD-AgNPs as simple, rapid, sensitive, selective colorimetric sensors with high potential for rapid and on-site detection of Mn2+ and Cr2+ ions.

Synthesis of mycogenic zinc oxide nanoparticles and preliminary determination of its efficacy as a larvicide against white grubs (Holotrichia sp.)

In the present study, the larvicidal efficacy of mycogenic zinc oxide nanoparticles (ZONPs) were tested against white grubs, a potent pest of sugarcane in western Uttar Pradesh (India). The ZONPs were synthesized using Aspergillus niger biomass and characterized using UV–Vis spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), dynamic light scattering (DLS) and Fourier transform infrared (FTIR). the parts per million (ppm) concentration of synthesized ZONPs was established by the inductively coupled plasma mass spectrometry (ICPMS) technique and several ppm dilutions were prepared to determine 50% lethal dose (LD50). The UV–Vis spectroscopy showed peaks at 240, 290, 340, and 380 nm, corresponding to ZONPs. The FESEM results also confirmed the synthesis of nano-sized particles. EDX analysis result showed the optical absorption peaks specific to ZONPs. The DLS result confirmed the synthesis of ZONPs with sizes ranging from 76.2 to 183.8 nm. The FTIR spectrum analysis confirmed the presence of various functional group interactions in the nanoparticle sample. The ZONPs were tested against the first instar larvae of white grubs. The LD50 was calculated to be 12.63 ppm which still needs to be validated for significance. In the near future, we are planning to establish the minimal lethal dosage of ZONPs to prepare effective larvicidal formulations against white grub infection with minimal toxicity to the environment.

Ultrasound-Activated Cascade Effect for Synergistic Orthotopic Pancreatic Cancer Therapy.

SummaryIn some malignant tumor, especially for pancreatic tumor, poor solid-tumor penetration of nanotherapeutics impedes their treatment efficacy. Herein, we develop a polymer-peptide conjugate with the deep tissue penetration ability, which undergoes a cascade process under ultrasound (US), including (1) the singlet oxygen 1O2 is generated by P18, (2) the thioketal bond is cleaved by the 1O2, (3) the departure of PEG chains leads to the in situ self-assembly, and (4) the resultant self-assembled PK nanoparticles show considerable cellular internalization. Owing to the synergistic effect of US on increasing the membrane permeability, the endocytosis and lysosome escape of PK nanoparticles are further enhanced effectively, resulting in the improved therapeutic efficacy. Thanks to the high tissue-penetrating depth and spatial precision of US, PTPK presents enhanced tumor inhibition in an orthotopic pancreatic tumor model. Therefore, the US-activated cascade effect offers a novel perspective for precision medicine and disease theranostics.

The aggregation behavior of fluorinated surfactant in an ionic liquid

Although ionic liquids have been studied as self-assembly media, the aggregation of fluorinated surfactants in ionic liquids has not been fully understood. In this work, the aggregation behavior of the fluorinated surfactant, N-ethylperfluorooctane sulfonamide (N-EtFOSA), in the aprotic ionic liquid, 1-ethyl-3-methylimidazolium ethylsulfate ([C2mim][EtSO4]), was studied using surface tension, 19F-NMR, dynamic light scattering (DLS), and cryo transmission electron microscopy (cryo-TEM). The surface properties and thermodynamic parameters were calculated based on the results of surface tension measurements. It was found that the fluorinated surfactant exhibits a considerable surface activity in aprotic ionic liquids, and its critical micelle concentration (cmc) increases with increasing temperature. In addition, the surface properties indicate that solvophobic interactions are the main driving force for micelle formation. The thermodynamic parameters for micelle formation derived from the temperature dependence of the cmc revealed that micelle formation is an enthalpy-driven process. DLS and cryo-TEM results indicated the presence of nanoscale micelles in the N-EtFOSA + [C2mim][EtSO4] system. The results of this work imply that this fluorinated surfactant exhibits a more pronounced surface activity than conventional hydrocarbon surfactants in [C2mim][EtSO4].

Mechanisms of interaction of Cetylpyridinium chloride with Staphylococcus aureus in the presence of β-cyclodextrin

Cetylpyridinium chloride (CPC) is a cationic surfactant, which has a biocidal activity against a broad spectrum of bacteria, including Staphylococcus aureus. This microorganism, although frequently found in the normal human microbiota, can become a pathogen that causes a wide variety of infections. Thus, the present work aims to investigate the effect of the β-cyclodextrin (βCD) on CPC antimicrobial activity against S. aureus, especially in the mechanism of interaction with S. aureus membrane. For these purposes, in vitro antimicrobial susceptibility of CPC and CPC/βCD compounds against S. aureus were determined by calculating the lower concentration capable of reducing cell viability by 50 and 100 percent, and the kinetics of bacterial death were evaluated by kill curves for the two systems. After that, the colloidal mechanisms of interaction of the CPC and CPC/βCD against S. aureus were investigated by Dynamic Light Scattering (DLS) and Zeta Potential (ZP) titrations. Finally, the thermodynamic parameters of drug-cell interaction were determined by Isothermal Titration Calorimetry (ITC), in order to obtain deeper understanding of the mechanism of drug interactions. The results of DLS, ZP and ITC showed that in presence of βCD occurs a different mechanism of interaction with S. aureus membrane, explaining therefore the higher antimicrobial activity of CPC/βCD system.

E. coli production process yields stable dengue 1 virus-sized particles (VSPs)

Dengue fever is one of the most wide-spread vector-borne diseases in the world. Although dengue-associated mortality is low, morbidity and economic impact are high. Current licensed vaccines are limited and mediate only partial protection, thus a cost-effective vaccine with improved efficacy is strongly needed.In this work, recombinant dengue serotype 1 E protein was produced in E. coli, inclusion bodies were isolated and the E protein solubilized in urea and purified using an immobilized metal chelate affinity column. The protein was refolded by dialysis in order to obtain virus-like particles (VLPs).Particle assembly was confirmed using size-exclusion chromatography, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy and stimulated emission depletion fluorescence (STED) microscopy. Particle diameter was strongly dependent on temperature, pH, buffer salt composition, and addition of L-arginine. Particles were stable in carbonate buffer at pH 9.5 and higher at 4 °C and did not aggregate during short-term temperature increase up to 55 °C.However, on basis of the above analyses, especially the results of DLS, TEM and STED, it was concluded that the particles obtained did not have an optimal virus-like structure and were therefore designated “virus-sized particles” (VSPs) rather than VLPs.Immunization of rabbits with the particles did not induce neutralizing antibodies, despite the recognition of the native virus by rabbit antibodies. As the titers against the immunogen were much higher than against the (heat-inactivated) virus, it is assumed that the conformation of the particles at the time of immunization was not optimal. Studies are currently underway to improve the quality of the E protein virus-sized particles towards true virus-like particles in order to optimize its potential as a dengue vaccine candidate.

Inclusion complexation of imidazolium-based ionic liquid and β-cyclodextrin: A detailed spectroscopic investigation

Host-guest inclusion complexation (IC) behavior of ionic liquid (IL) 1-decyl-3-methylimidazolium tetrafluoroborate [Dmim][BF4] within β-cyclodextrin (β-CD) and the nature of complexation as well as binding affinity were studied in aqueous solution with the help of different spectroscopic methods i.e., fluorescence, dynamic light scattering (DLS), UV–vis, FTIR, and 1H NMR spectroscopy. The nature of complexation has been established from the results obtained for critical micelle concentration (cmc), aggregation number (Nagg), Stern-Volmer constant, particle size. Fluorescence and UV–vis studies revealed that 1:1 M stoichiometry of the ICs, while FTIR and DLS studies show the formation of H-bonding, electrostatic, hydrophobic interactions within the system and size of ICs formed. IL [Dmim][BF4] imparts distinctive properties of the ICs along with the instantaneous presence of vesicle and micelle which is well supported by DLS results. Binding constants for β-CD and [Dmim][BF4] complexes have been derived using Benesi-Hildebrand method and the thermodynamic properties have been evaluated with the help of van't Hoff equation. 1H NMR results are significant to show the changes for chemical shift of the β-CD and [Dmim][BF4] complexes which reveals that alkyl part of the IL is inserted into the hydrophobic cavity of β-CD. The obtained results on the ICs of [Dmim][BF4]/β-CD in this article can find potential application in soft matter construction, sensing and drug delively.

Synthesis and Aggregation Behavior of Jellyfish-Shaped Triazine Hexamer Quaternary Ammonium Chloride Surfactant

A novel jellyfish-shaped triazine hexamer quaternary ammonium chloride surfactant (TH12QC) was synthesized, which consisted of one triazine spacer group and six long flexible hydrophobic chains. The molecular structure and aggregation behavior of TH12QC was investigated by nuclear magnetic resonance (NMR), surface tension, electrical conductivity, dynamic light scattering (DLS), transmission electron microscope (TEM), etc. The results show that the jellyfish-shaped TH12QC has better surface activity and lower surface tension than traditional ionic and Gemini surfactants in aqueous solution. There are two inflection points in the curve of conductivity versus concentration of the TH12QC aqueous solution, which correspond to the critical aggregation concentration (CAC) and the critical micelle concentration (CMC) respectively. The existence of CAC indicates that there is a pre-aggregation process before TH12QC forms micelles. The results of DLS and TEM show that network pre-aggregation, spherical aggregation and dense spherical aggregation were observed in different concentration of TH12QC aqueous solution, and the electrostatic equilibrium of the system subtly depends on the concentration of the solution. In addition, intramolecular and intermolecular hydrogen bonding is also an important factor. This study provides a method for studying the aggregation behavior and morphology of oligomeric surfactants with rigid spacer groups.

Evaluation the antibacterial activity of nanoantibiotics imipenem and ciprofloxacin loaded in human serum albumin against some antibiotic-resistant pathogenic bacteria

Introduction Microbial resistance is increasing worldwide. Investigations are underway to use nanoparticles as antimicrobial agents to reduce microbial resistance. Materials and methods Seven human pathogenic bacteria were selected according to common hospital infection bacteria: both gram-positive and negative. In this study, imipenem and ciprofloxacin antibiotics were used separately and in combination with human serum albumin and coacervation method for the preparation of nanoparticles. Dynamic light scattering (DLS), scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR) were used to investigate the properties of nanoparticles. Antibacterial activity was determined and compared using the disk diffusion technique and minimum inhibitory concentration (MIC) was determined. Results The results of DLS for imipenem, ciprofloxacin and the combination of both antibiotics were 85 nm, 135 nm, and 120 nm, and for SEM were 79.9 nm, 122.2 nm, and 111 nm, respectively. All of the synthesized nanoparticles have a spherical shape. The antibacterial effect on the disk diffusion test for Acinetobacter baumannii bacteria was more noticeable in all three HSA nanoparticle compositions than other bacteria. The use of antibiotics in the form of HSA nanoparticles reduced the MIC. This value was more significant for nanoparticles carrying both ciprofloxacin and imipenem on methicillin-resistant Staphylococcus aureus and Streptococcus mutans bacteria. Conclusion From the results of this study, it can be concluded that the use of HSA nanoparticles carrying the aforementioned antibiotics has more antibacterial effect against the bacteria of this study, especially S. mutans, than their free form.