Dynamic Light Scattering Technique Research Articles

Evaluation and Comparison of Fullerene (C60) Aqueous Suspension Administration Effects with Memantine HCL in Rat Model of Alzheimer’s Disease Considering Behavioral Patterns and Spatial Memory

: Alzheimer's disease (AD) is among the most prevalent neurodegenerative disorders leading to dementia in the elderly. The accumulation of amyloid-beta (Aβ) plaques and the formation of tau protein tangles are primary contributors to AD, which induce oxidative stress. Fullerene C60, a nanoscale carbon allotrope with a diameter of 0.7 nanometers, stands out due to its structure rich in double bonds, making these nanoparticles effective radical scavengers. This property nominates them for potential use in treating neurodegenerative diseases like AD. In this study, unmodified pristine fullerene (C60), a highly hydrophobic molecule, was dispersed in water and administered intraperitoneally (1 mL, BID) to rats after inducing an AD-like condition with scopolamine hydrobromide (2mg/kg, i.p.). The aim was to assess the impact of fullerene (C60) treatment on cognitive behavior and spatial memory in rats, compared to the standard treatment with memantine HCL, using the Morris water maze method. The fullerene aqueous suspension (FAS) was prepared using a solvent exchange method involving a toluene/water mixture and ultrasonication. The concentration of fullerene particles in water was determined by high-performance liquid chromatography (HPLC) to be 21 µg/mL. The Dynamic Light Scattering (DLS) technique measured the average size and zeta potential of the nanoparticles as 119.14 ± 3.38 nm and -12.22 ± 5.98 mV, respectively. Treatment with FAS significantly improved memory impairment in rats compared to memantine HCL (10 mg/kg, i.p.) treatment. All rats survived until the end of the study, indicating no acute toxicity from FAS administration. These results may offer new insights into combating AD by introducing fullerene C60 as a promising nanoparticle with beneficial effects on behavioral patterns.

Dynamic Light Scattering for the Measurement of Transport Properties of Fluids

The present article summarizes experimental and theoretical considerations required for a proper use of dynamic light scattering (DLS) for the measurement of transport properties of fluids. It addresses not only recent advancements of the method, but also aims to provide recommendations to researchers who intend to apply the technique in the future. As outlined in this study, DLS is based on the analysis of scattered light governed by microscopic statistical or periodic fluctuations that originate from the thermal movement of molecules and/or particles at macroscopic thermodynamic equilibrium. The dynamics of these hydrodynamic fluctuations in the bulk of fluids or at their phase boundaries are related to the underlying diffusive processes and, thus, to the associated transport properties, and are reflected by the time-dependent correlation function of the scattered light intensity. The fundamentals of this type of detection, known as photon correlation spectroscopy (PCS), will be discussed in the present contribution in some more detail. It is emphasized that the experiments need to be designed carefully in accordance with theory in order to assign the measurement signals to the corresponding hydrodynamic fluctuations. If the necessary conditions are fulfilled, DLS allows the accurate determination of several transport properties including kinematic and dynamic viscosity, thermal diffusivity, mutual diffusivity, and sound attenuation, which may be accessed together with other thermophysical properties such as speed of sound and surface or interfacial tension. In some instances, also the simultaneous determination of several transport properties is possible. With the exception of the sound attenuation, expanded uncertainties for the mentioned transport properties down to 1 % can be achieved for various types of fluid systems over a wide range of thermodynamic states up to elevated temperatures and pressures as well as in the vicinity of critical points. This performance and versatility of the DLS technique is documented in the present study by highlighting measurement examples from recent thermophysical property research on different classes of working fluids relevant for process and energy technology.

A regularization algorithm of dynamic light scattering for estimating the particle size distribution of dual-substance mixture in water

Dynamic light scattering (DLS) is a nondestructive, well-established technique for the size characterization of proteins, nanoparticles, polymers, and colloidal dispersions. However, current DLS techniques are only applied to particle groups of single composition due to the limitation of their inversion algorithm. In this study, we propose a particle size distribution inversion algorithm based on the Tikhnonov regularization method that can be applied to the dual-substance particle mixture. The algorithm retrieves the particle size distributions of two substances, respectively, by taking advantage of their refractive index differences. The simulation results reveal that the algorithm has excellent accuracy and stability when the scattering angle is 30°. Instead of the original identity matrix, the first-order difference matrix and second-order difference matrix are used as the regular matrix when utilizing the Tikhnonov algorithm, which obviously improves the anti-interference, accuracy, and stability of the algorithm. Furthermore, the inversion of particle size distribution is carried out at a 0.01%–1% noise level, which shows that the algorithm has an available antinoise ability. Finally, experimental particle size measurements for a mixture of polystyrene beads and toner particles demonstrate that the proposed algorithm is superior to the traditional Tikhnonov algorithm in applicability and accuracy.

A new nanobiotic: synthesis and characterization of an albumin nanoparticle with intrinsic antibiotic activity.

With entering the "post-antibiotic era", antibiotic resistance is one of the most important problems in food security, health and medicine. Invention of nanoparticles with intrinsic antimicrobial activity has been provided a new tool to combat the problem, including some metal nanoparticles. But protein nanoparticles have been often used as nano-carrier for antibiotic drugs, not for their own antibiotic activity. In this article we have fabricated a very small BSA-NP without any chemical modification on BSA molecules showing antibacterial activity. Bovine serum albumin nanoparticle (BSA-NP) was synthesized using botton-up approach, by dissolution of BSA in urea-containing Tris buffer for 60 min at 60°C. Then, the BSA solution was dialyzed against distilled water in order to nanoparticle formation. The resulted BSA-NP has been characterized by dynamic light scattering (DLS), field emission surface electron microscopy (FESEM), SDS-PAGE, Fourier transform infrared spectroscopy (FTIR) and UV-spectrophotometery. Minimum inhibitory concentration (MIC) method was used for evaluation of antibacterial activity of BSA-NP against Staphylococcus aureus and Pseudomonas aeruginosa. The results obtained by DLS technique indicated that BSA molecules were self-assembled into small aggregates with a hydrodynamic diameter of 23.23 ± 2.1 nm. With a small polydispersity index (PDI=0.522), the nanoparticles had good spherical uniformity. The nanoparticles made from a single type of protein molecule (BSA) and have a relatively transparent appearance. The BSA-NPs caused a decrease in cell growth of both P. aeruginosa and S. aureus. Moreover, they had a bacteriostatic effect on P. aeruginosa (MIC=112×10-5 μM). In this study, using a green synthesis method, we succeeded in synthesizing a very small uniform BSA nanoparticles without any chemical modification on BSA molecules. It also has bacteriostatic properties against P. aeruginosa. Therefore, it is hypothesized that our BSA-NPs may be effective as a new approach to combat antibiotic resistance.

CTAB induced growth and shrinkage of Pluronics® P103 micelles: Experimental and theoretical rationale

This study offers an insight into the concentration influence of a cationic surfactant- cetyltrimethylammonium bromide (CTAB) having a 16-carbon long alkyl side chain that influences the self-assembly and micellization behaviour of a linear triblock copolymer based on ethylene oxide (EO) and propylene oxide (PO) Pluronic® P103 in aqueous solution. The work makes an exclusive use of a variety of methodologies, such as high sensitivity differential scanning calorimetry (HSDSC), phase behaviour study, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The investigation on the clouding behaviour demonstrates that the cloud point value of 5 %w/v P103, which is typically in the vicinity of 90 °C, rises up to more than 100 °C with the addition on of very low concentration of CTAB. The DLS technique predicted the change in hydrodynamic diameter (Dh) of micelles with temperature and in varying CTAB concentration. The SANS results inferred the morphological changes in the micelles. A comprehensive approach revealing the relationship between the molecular orbital energies of the tested P103 and CTAB were assessed by utilising the computational simulation method with the Gaussian 09 calculation window and Gauss View 5.0.9 software. The perception of CTAB-stabilized Pluronics® micelles is predicted to be much improved from the evaluated optimised descriptors. Additionally, our examined micellar system revealed the solubilization enhancement of a model hydrophobic dye orange-OT utilizing UV–vis spectroscopy.

Dispersion stability analysis of copper sulphide nanoparticles in different medium

Nanoparticles (NPs) of covellite CuS have been synthesised using a modified polyol method at 160ºC - 165ºC without adding any extra surfactant. These NPs were charecterized by X-ray diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Analysis of X-ray (EDAX), Zeta potential and Dynamic Light Scattering (DLS) techniques. XRD data and three Raman modes confirm P63/mmc space group and hexagonal crystal structure of CuS NPs. EDAX data of Cu:S was slight differed from nominal 1:1 ratio due to extra S taken in synthesis. FESEM images show sheet-like NPs. The zeta potential (ξ) data analysis shows that the stability of the NPs is dependent on the dispersion medium, with high stability observed above pH 8.93 in an acidic medium. At pH 10.95, a highest ξ value of -37.64 mV is recorded in de-ionized water (DIW), while the nanoparticles are found to be unstable in ethanol and propanol as dispersion mediums. According to the hydrodynamic diameter (HD) data, the particles tend to agglomerate more quickly in ethanol and propanol compared to DIW. These findings are expected to be useful in various applications such as pigments in paints, batteries, pharmaceuticals, ceramics, and waste water treatment.

Variance analysis of dynamic light scattering data.

We propose a novel method alternative to the classical Dynamic Light Scattering (DLS) technique for performing particle sizing on diluted dispersions of nanosized particles. Differently from DLS, which works by determining the correlation function of the intensity scattered by the sample, our method does not require the use of a correlator because it exploits the behavior of the variance (VAR) of the scattered signal as a function of the sampling time Δt. By using a wide range of sampling times Δtmin ≪ τc ≪ Δtmax, it is possible to recover the correlation time τc of the scattered field and, in turn (by using the Stokes-Einstein relation), the hydrodynamic diameter of the particles. The new method is endowed with an analytical expression for the error bars associated with to the VAR data. Extensive computer simulations carried out on monodisperse and narrow polydisperse samples show that VAR and DLS techniques provide fairly similar performances. The same results were obtained on calibrated polystyrene spheres and fluorescent perovskite nanoparticles tested with different setups and detection schemes.

Enhanced photocatalytic activity in RhB dye degradation by Mn and B co-doped mixed phase TiO2 photocatalyst under visible light irradiation

Here, we report synthesis of undoped, manganese (Mn) doped, boron (B) doped and Mn-B co-doped TiO2 nanoparticles (NPs) by a cost-effective sol-gel method. The structural properties, phase, micro-morphology and particle size of the synthesized nanoparticles have been characterized by X-ray diffraction, Raman spectroscopy, Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) techniques. These studies revealed that undoped and mono (Mn/B) doped TiO2 NPs exhibit only anatase phase, whereas (Mn and B) co-doped TiO2 NPs exhibit anatase and rutile mixed phase structure. Furthermore, co-doping reduces the particle size, agglomeration in aqueous medium and the sample possesses crystal defects. UV–Visible diffusive reflectance spectroscopy (DRS) revealed that the co-doped sample demonstrates extended optical response in the visible wavelength range of the solar spectrum and is red shifted when compared to undoped and mono doped TiO2 NPs. The obtained optical band gap (2.11 eV) and the Urbach energy (1.12 eV) for the Mn and B co-doped TiO2 NPs suggest the formation of mid-gap energy states, which might make this NPs a suitable candidate for photocatalysis in the visible light spectrum. We investigated the photocatalytic degradation of rhodamine B (RhB) dye by the synthesized NPs under visible light irradiation. Our studies revealed that co-doped TiO2 photocatalyst can degrade 99% of RhB dye within 90 min of visible light irradiation and can retain 95% degradation efficiency up to the third consecutive cycles. Finally, we provide a plausible explanation for such enhanced visible light assisted photocatalytic performance.

Role of Biosynthesized Silver Nanoparticles with Trigonella foenum-graecum Seeds in Wastewater Treatment

As the human population continues to escalate, its requirement for clean water is also increasing. This has resulted in an increased dependency on wastewater effluent to maintain the base flow of urban streams, especially in water-stressed regions. The present study reports the synthesis of AgNPs with green credentials using an aqueous extract of Trigonella foenum-graecum seeds. The observance of surface plasmon resonance (SPR) with UV–Vis spectrophotometry confirmed the presence of spherical/oblong particles with a mean diameter of 43.8 nm and low polydispersity index (PDI) of 0.391 measured by transmission electron microscopy (TEM) and DLS (dynamic light scattering) technique, respectively. The elemental map of AgNPs was demonstrated with energy-dispersive spectroscopy (EDS) and the constituent functional groups were identified by the FTIR spectra, which were similar to the bulk seed extract with a slight shift in the pattern. The emission spectrum of nanoparticles was recorded for the excitation wavelength of 349 using fluorescence microscopy and the crystalline structure was assessed using X-ray diffraction. The potential wastewater remedial efficacy of the synthesized AgNPs was evaluated based on the water quality parameters (pH, EC, BOD, COD) of the sewage effluent collected from a local Sewage Treatment Plant (STP). Furthermore, the photo degradative efficacy was investigated using the degradation percentage of Crystal Violet (CV) dye, which was recorded as 94.5% after 20 min. In addition, the antimicrobial activity of the NPs versus bulk seed extract was assessed against two bacterial strains, Escheria coli and Staphylococcus aureus, using the disc diffusion method. The AgNPs showed a profound modulatory effect on the water quality parameters, coupled with marked antimicrobial and photodegradative activity. Thus, the biogenically synthesized AgNPs offer a prospective potential for use in wastewater remediation strategies.

Deciphering the anticancer, anti-inflammatory and antioxidant potential of Ti nanoparticles fabricated using Zingiber officinale

Rapid and sustainable green technology was implemented in the current study to fabricated Ti nanoparticles. The vegetable ginger with the scientific name Zingiber officinale was employed as a biological source in the fabrication process of nanoparticles. The optical, structural, morphological, and particle size of the fabricated Ti nanoparticles were characterized with the help of UV–visible absorption spectrum, FTIR (Fourier Transform Infrared) spectrum, SEM (Scanning Electron Microscope) analysis, DLS (Dynamic Light Scattering) technique and XRD (X-ray powder diffraction) crystallography technique. The presence of spherical-shaped Ti nanoparticles with an average particle size of 93 nm was confirmed based on these characterization techniques. The anti-cancer properties of the Z. officinale mediated Ti nanoparticles were analyzed through MTT assay against cell lines MCF-7 (Human breast adenocarcinoma cell line) and concentration-dependent anti-cancer properties were observed. The anti-inflammatory capacity of the Z. officinale mediated Ti nanoparticles were examined through protein denaturation and nitric oxide scavenging assay. The antioxidant capacity of the Z. officinale mediated Ti nanoparticles were examined through DPPH assay, hydrogen peroxide radical scavenging assay, hydroxyl radical scavenging assay, and FRAP (Ferric Reducing Antioxidant Power) analysis. The fabricated Ti nanoparticles exhibited anti-inflammatory and antioxidant capacity in a concentration-dependent pattern.

Behaviour and fate of Ag-NPs, TiO2-NPs and ZnO-NPs in the human gastrointestinal tract: Biopersistence rate evaluation.

This study aims to provide information on the behaviour and biopersistence rate (BP) of metallic nanoparticles (Ag-NPs, TiO2-NPs, ZnO-NPs) naturally occurring in canned seafood and subjected to static in vitro digestion. Single particle ICP-MS analysis was performed to determine NPs distribution and concentrations in oral, gastric, and intestinal digests. Depending on the conditions of the digestive phase and the sample matrix, the phenomena of agglomeration and dispersion were highlighted and confirmed by Dynamic Light Scattering (DLS) technique. In standard suspensions, Ag-NPs had lower biopersistence (BP) than ZnO and TiO2-NPs (BP 34%, 89% and >100%, respectively). Among Ag-NPs and TiO2-NPs naturally present in the food matrix, those in canned tuna were more degradable than those in canned clam (BP Ag-NPs 36% vs. > 100%; BP TiO2-NPs 96% vs. > 100%), while BP ZnO-NPs showed high biopersistence in both seafood matrix (>100%). The biopersistence rates were higher than the recommended limit set by European Food Safety Authority (EFSA) (12%), referred to nanotechnologies to be applied in the food and feed chain, thus the investigated naturally occurring NPs cannot be considered readily degradable.

Laponite Composites: In Situ Films Forming as a Possible Healing Agent.

A healing material must have desirable characteristics such as maintaining a physiological environment, protective barrier-forming abilities, exudate absorption, easy handling, and non-toxicity. Laponite is a synthetic clay with properties such as swelling, physical crosslinking, rheological stability, and drug entrapment, making it an interesting alternative for developing new dressings. This study evaluated its performance in lecithin/gelatin composites (LGL) as well as with the addition of maltodextrin/sodium ascorbate mixture (LGL MAS). These materials were applied as nanoparticles, dispersed, and prepared by using the gelatin desolvation method-eventually being turned into films via the solvent-casting method. Both types of composites were also studied as dispersions and films. Dynamic Light Scattering (DLS) and rheological techniques were used to characterize the dispersions, while the films' mechanical properties and drug release were determined. Laponite in an amount of 8.8 mg developed the optimal composites, reducing the particulate size and avoiding the agglomeration by its physical crosslinker and amphoteric properties. On the films, it enhanced the swelling and provided stability below 50 °C. Moreover, the study of drug release in maltodextrin and sodium ascorbate from LGL MAS was fitted to first-order and Korsmeyer-Peppas models, respectively. The aforementioned systems represent an interesting, innovative, and promising alternative in the field of healing materials.

Elucidating the effects of dispersion methods on agglomerated nano silica particles in aqueous environment

A zero-dimensional Nano silica (NS) particle possess a wide range of application in multi-variant fields due to its size, amorphous nature and silica content in spite of its hydrophilic and hydrophobic behaviour. These nano particles are synthesized and commercially supplied in the size range of 1–100 nm with high Specific Surface Area (SSA). Due to agglomeration, these NS particles are sized between 1 and 100 μm which in turn reduces its SSA and thereby limiting its efficient utilisation. As a pragmatic solution, the current study involves in defining the suitable dispersion method for NS particles in aqueous environment. The effects of both mechanical and physical surface modification of nano particles using Superplasticizer (SP) since the incorporation of NS particles that aim at cementitious system are investigated. NS particles acts as nucleation seeds in cement hydration which directly relay on its particle size. The mechanical modification methods such as Ultrasonication and high shear mixer are employed to reduce the agglomerates size. Whereas the effect of steric (electrostatic mechanism) and Vander Waals attraction between the deagglomerated particles are studied. The stability and the size histogram of deagglomerated nano particles are thoroughly assessed with Dynamic Light Scattering (DLS) technique. From the findings, it is interpreted that the combination of mechanical and surface modification effectively reduces the size of agglomerates as well as the intensity of surface attractive forces between the particles with respect to its dosage in aqueous medium.

Comparison of Fabrication Technique and Carrier Oil to Curcumin Nanoemulsion Properties

Turmeric (Curcuma longa L.) is included in the rhizome plant containing curcumin which has various therapeutic properties. However, curcumin has poor bioavailability. The manufacture of nanoemulsion is expected to increase curcumin bioavailability. This study aims to compare 3 methods (wet-ball milling, ultrasonication and microfluidic) and 3 carrier oils (soybean, virgin coconut, and olive oil) in the production of curcumin nanoemulsion. Wet-ball milling reduces particle size through grinding process using milling beads in liquid medium. Microfluidic decreases the particle size via collision of emulsion components in microchannel while ultrasound utilizes sound-wave energy to break down the particle size. Parameters compared were particle size, polydispersity index and entrapment efficiency. Particle size and polydispersity index were observed using Particle Size Analyzer with Dynamic Light Scattering technique while entrapment efficiency was measured based on the curcumin absorbance in UV-Visible spectrophotometer at 420 nm. Our study concludes that microfluidic is the most effective and efficient fabrication method which produces the smallest particle size and polydispersity index compared to ultrasonication and microfluidic. The resulting particle sizes using microfluidic are 154, 140 and 132 nm with polydispersity index of 0.224; 0.200 and 0.208 in soybean, virgin coconut, and olive oil respectively. However, entrapment efficiency is best achieved using wet-ball milling method with the average value of 49±10%. Soybean oil appears to be the most curcumin solubilizing oil compared to olive and virgin coconut oil. Thus, it can be concluded that fabrication methods and carrier oils determine curcumin nanoemulsion properties.

Acrylonitrile adducts: design, synthesis and biological evaluation as antimicrobial, haemolytic and thrombolytic agent

In this work, five acrylonitrile adducts were screened for antibacterial activity against Gram-positive Bacillus subtilis, Microbial Type Culture Collection and Gene Bank (MTCC 1305) and Gram-negative Escherichia coli (MTCC 443). Synthesis was followed by aza-Michael addition reaction, where the acrylonitrile accepts an electron pair from the respective amines and results in the formation of n-alkyliminobis-propionitrile and n-alkyliminopropionitrile under microwave irradiation. Characterization of the compounds were performed using Fourier Transform Infrared (FTIR), Proton Nuclear Magnetic Resonance (1H NMR) and Electrospray Ionisation Mass Spectrometry (ESI–MS). The particle size characterization was done by Dynamic Light Scattering (DLS) technique. The antibacterial study showed higher inhibition rate for both Gram-positive and Gram-negative bacteria. The antibacterial ability was found to be dose dependent. The minimum inhibitory concentration against both bacteria were found to be 1, 3, 0.4, 1, 3 µl/ml for E. coli and 6, 6, 0.9, 0.5, 5 µl/ml for B. subtilis. Time-kill kinetics evaluation showed that the adducts possess bacteriostatic action. Further it was evaluated for high-throughput in vitro assays to determine the compatibility of the adducts for drug delivery. The haemolytic and thrombolytic activity was analysed against normal mouse erythrocytes. The haemolytic activity showed prominent results, and thereby projecting this acrylonitrile adducts as potent antimicrobial and haemolytic agent.

Metrology and Nanometrology at Agricultural/Food/Nutraceutical Interface: An Updated Shot

Abstract: Nanometrology has been considered as a key to the future of nanotechnology since recently. It is particularly important for nanoparticle market development that is commonly applied in dif-ferent areas of science. The adoption of nanotechnologies in food and agrochemical industries represents a new frontier, with particular regard to plant defence against pathogen agents. Na-nometrology deals with a broad range of measurements, as well as chemical and structural characterization, electronic, thermal, and mechanical properties, fabrication and monitoring of nanodevices, and theoretical modelling of nanomaterials properties. Besides the scientific and technological values of a global standard offered by nanometrology, there are also several in-dustry-related values. In this paper, the most common the areas of science emphasized on the most frequently applied methods by the example of techniques/tools that have been described from a metrological standpoint at a nano size scale. Therefore, at the microscopic scale may be widely applied: optical techniques, for example, X-ray Photoelectron Spectroscopy (XPS), or op-tical transmission. Moreover, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) can be used for microscopic characterization, while Scanning Probe Micros-copy (SPM), consisting of Scanning-Tunnelling Microscopy (STM) and Atomic Force Microscopy (AFM), as well as Transmission-Electron Microscopy (TEM), can be employed at the nanoscopic scale. The review has also mentioned about Secondary Ion Mass Spectroscopy (SIMS) to analyze secondary ions using a mass spectrometer. In addition, Electron Energy Loss Spectroscopy (EELS) using high-energy electrons from sample penetration or Fourier Transform Infrared Spectroscopy (FTIR) to obtain the infrared spectrum of a sample were also presented. Particle size analysis can be analyzed by performing Small-/Wide-Angle X-ray Scattering (SAXS/WAXS) and Dynamic Light Scattering (DLS) techniques. A specific metrology approach is required for most nanoparticle-based products, that is, the way nanometrology is significant for production quality control and for toxicology studies. This review wants to give an updated shot on the metrological approaches and applications, with particular attention to nanometrology for dif-ferent areas of scientific research, i.e., food, agricultural, nutraceutical, biological and medical ones. The novelty character of this paper is to discuss the application of nanotechnologies under metrological principles and approach at the interface of different integrated, multipurpose and multidisciplinary application fields. The following topics are here explored: i) metrology: defi-nitions, principles, and main features; ii) calibration methods and techniques; iii) measurement methods and systems; iv) proficiency testing; v) nanometrology. Particularly, nanometrology was highlighted in the following directions: significance of the nanodimension, nanometrology in chemical research, nanometrology for the characterization of nanoparticles, nanometrology in biological and medical sciences, mechanical nanometrology, electrical nanometrology and applications of nanometrology in agriculture and food industry.

The microwave-assisted synthesis of silica nanoparticles and their applications in a soy plant culture.

A rapid and environmentally friendly synthesis of thermodynamically stable silica nanoparticles (SiO2-NPs) from heating via microwave irradiation (MW) compared to conductive heating is presented, as well as their evaluations in a soy plant culture. The parameters of time and microwave power were evaluated for the optimization of the heating program. Characterization of the produced nanomaterials was obtained from the dynamic light scattering (DLS) and zeta potential analyses, and the morphology of the SiO2-NPs was obtained by transmission electron microcopy (TEM) images. From the proposed synthesis, stable, monodisperse, and amorphous SiO2-NPs were obtained. Average sizes reported by DLS and TEM techniques were equal to 11.6 nm and 13.8 nm, respectively. The water-stable suspension of SiO2-NPs shows a zeta potential of -31.80 mV, and the homogeneously spheroidal morphology observed by TEM corroborates with the low polydispersity values (0.300). Additionally, the TEM with fast Fourier transform (FFT), demonstrates the amorphous characteristic of the nanoparticles. The MW-based synthesis is 30 times faster, utilizes 4-fold less reagents, and is ca. 18-fold cheaper than conventional synthesis through conductive heating. After the synthesis, the SiO2-NPs were added to the soil used for the cultivation of soybeans, and the homeostasis for Cu, Ni, and Zn was evaluated through the determination of their total contents by inductively coupled plasma mass spectrometry (ICP-MS) in soy leaves and also through bioimages obtained using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Although the results corroborate through both techniques, they also show the influence of these nanoparticles on the elemental distribution of the leaf surface with altered homeostasis of such elements from both transgenic crops compared to the control group.

Laser Intensity of Thermo-Responsive Nanoparticles Size Measurement Using Dynamic Light Scattering

Dynamic light scattering (DLS) or photon cross-correlation spectroscopy (PCCS) is a very potent means for analyzing the diffusion behaviour of supramolecules in their solution form. The diffusion coefficient, probed from the scattered light by supramolecules underexposure to incident light, allows the hydrodynamic radii to be calculated. However, the scattering values were recently misled by an unexpected interaction between the incident light and thermo-sensitive nanogels. Hence, in turn, it resulted in a miscalculation of the size of the nanogels by more than 100% of their expected values. The study fulfills a vital knowledge gap by investigating the effects of laser intensity on the size of thermo-sensitive Poly(N-Isopropyl Acrylamide-Vinyl Pyrrolidone-Polyethylene Glycol Diacrylate-(2-(Dimethyl Amino)Ethyl Methacrylate)), Poly(NIPAAM-PVP-PEGDA-DMAEMA) nanogels and subsequent count rates in DLS measurements. The Lower Critical Solution Temperature, LCST phase transition of Poly(NIPAAM-PVP-PEGDA-DMAEMA) nanogel can be observed using the DLS technique. The higher laser intensity was advantageous for measuring at high dilution more vigorously with varying laser intensities. Thus, a sufficient laser intensity should be chosen based on the light scattering characteristics of typical samples.

Soil humic acid and arsenite binding by isothermal titration calorimetry and Dynamic Light Scattering: Thermodynamics and aggregation

The arsenite-humic acid binding process was investigated using Isothermal Titration Calorimetry (ITC), Dynamic Light Scattering and Laser Doppler Electrophoresis techniques. The ITC data were successfully (R2 = 0.996–0.936) interpreted by applying the MNIS model, enabling thermodynamic parameters to be determined. The MNIS model was adjusted to the arsenite-HA binding process assuming that hydrogen bonding is the dominant type of interaction in the system. Negative enthalpy change values indicated the arsenite-HAs binding as an exothermic process. Negative ΔG values (-(26.83–27.00) kJ mol−1) pointed out to spontaneous binding reaction, leading to the formation of the arsenite-HA complexes. The binding constant values ((7.57–5.02) 105 M−1) clearly demonstrate pronounced binding affinity. As ΔS values are obviously positive but close to zero, and ΔH>ΔS, the reaction can be considered enthalpy driven. Reaction heats and ΔH values (-(18.96–15.64) kJ mol−1) confirmed hydrogen bonds as the most ascendant interaction type in the arsenite-HA complex. Negative zeta potential values (−45 to −20 mV) had shown that arsenite-HA aggregates remained negatively charged in the whole molar charge ratio range. The HAs' aggregate size change is evident but not particularly pronounced (Zav = 50–180 nm). It can be speculated that aggregation during the titration process is not expressive due to repulsive forces between negatively charged arsenite-HA particles. Thermodynamic and reaction parameters clearly indicated that arsenite-HA complexes are formed at common soil pH values, confirming the possible influence of humic acids on increased As mobility and its reduced bioavailability.

Disposable Voltammetric Immunosensor for D-Dimer Detection as Early Biomarker of Thromboembolic Disease and of COVID-19 Prognosis

In this work, we report on the development of a simple electrochemical immunosensor for the detection of D-dimer protein in human plasma samples. The immunosensor is built by a simple drop-casting procedure of chitosan nanoparticles (CSNPs) as biocompatible support, Protein A (PrA), to facilitate the proper orientation of the antibody sites to epitopes as a capture biomolecule, and the D-dimer antibody onto a carboxyl functionalized multi-walled carbon nanotubes screen printed electrode (MWCNTs-SPE). The CSNPs have been morphologically characterized by Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS) techniques. Successively, the electrochemical properties of the screen-printed working electrode after each modification step have been characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The resulting MWCNTs-CSNPs-PrA-D-dimer Ab immunosensor displays an optimal and promising platform for antibody immobilization and specific D-dimer detection. DPV has been used to investigate the antigen/antibody interaction at different D-dimer concentrations. The proposed voltammetric immunosensor allowed a linear range from 2 to 500 μg L-1 with a LOD of 0.6 μg L-1 and a sensitivity of 1.3 μA L μg-1 cm-2. Good stability and a fast response time (5 s) have been reported. Lastly, the performance of the voltammetric immunosensor has been tested in human plasma samples, showing satisfactory results, thus attesting to the promising feasibility of the proposed platform for detecting D-dimer in physiological samples.