Histomorphometric and CBCT comparison of osseointegration around orthodontic titanium miniscrews coated with different nanoparticles: An in-vivo animal study

BACKGROUND

Temporarily installed titanium orthodontic miniscrews are usually used for many orthodontic applications, especially those cases that need high force, such as skeletally anchored orthodontic appliance cases. Surface modification of titanium miniscrews has proved success in preventing failure and overcoming their limitations.

OBJECTIVE

The present study aims at the assessment of the quality of osseointegration of surface modified titanium miniscrews installed in the maxilla of albino rabbits with cone-beam computed tomography (CBCT) imaging as well as histomorphometric investigations.

MATERIAL AND METHODS

The orthodontic titanium miniscrews (TMSs) were coated with silver/hydroxyapatite (Ag/HA) nanoparticles (NPs) or zinc oxide (ZnO) NPs via electrochemical deposition. The coating nanomaterials were then characterized with X-ray diffractometry (XRD) and scanning electron microscopy (SEM) imaging. Moreover, the antimicrobial activity of the coated titanium miniscrews were evaluated in the rabbits' oral cavity to investigate their ability to prevent biofilm formation.

RESULTS

It was found that the Ag/HA-coated TMSs demonstrated the highest antimicrobial activity and bone area fill, followed by the ZnO NPs-coated TMSs when compared to their uncoated counterparts. In the anterior area surrounding the installed TMSs, the highest osseointegration was demonstrated by ZnO NPs-coated TMSs. However, Ag/HA-coated TMSs showed the highest osseointegration values in the posterior peri-implant area.

CONCLUSIONS

Ag/HA- and ZnO NPs-coated TMSs may provide a promising solution to overcome the 30% probable failure in temporarily installed orthodontic miniscrews, as they can enhance the osseointegration process and prevent biofilm formation.

Triple-layered platform utilizing electrospun nanofibers and 3D-printed sodium alginate-based hydrogel for effective topical treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), an autoimmune disease impacting the joints, significantly diminishes the quality of life for patients. Conventional treatments predominantly rely on oral or injectable formulations, underscoring the crucial need for an effective topical remedy. The present study reports a novel triple-layered transdermal platform for efficient RA treatment. The patches are based on an electrospun/electrosprayed diclofenac (DIC)-conjugated polyvinyl alcohol (PVA) nanofibers/nanoparticles (NFs/NPs) composite layer sandwiched between an electrospun supporting layer of polycaprolactone (PCL) NFs, and a 3D-printed sodium alginate-based hydrogel (HG) layer incorporating sodium hyaluronate (HA) and rosuvastatin (ROS)-loaded core-shell lipid nanocapsules (LNCs). The ingeniously designed transdermal patches release the chemically conjugated DIC via skin-secreted esterases at the inflamed sites. The LNCs and patches were characterized using DLS, FTIR, DSC, and electron microscopy. ROS-loaded LNCs (<50 nm as per the TEM micrographs) were able to release about 97 % of ROS during 5 days. In-vitro and in-vivo evaluations definitively established the efficacy of the developed platform, showcasing a substantial reduction in IL-6 and TNF-α through sandwich ELISA measurements in cell culture and Rattus norvegicus plasma samples. Besides, the stained photomicrographs of the rats' ankle joints confirmed the alleviation of the RA symptoms via reducing cell infiltration with a preserved joint tissue structure.

Removal of bromophenol blue from polluted water using a novel azo-functionalized magnetic nano-adsorbent

Water pollution from organic dyes poses a serious danger to the environment. In the present work, we report a novel adsorbent (ADFS) based on azo-dye-functionalized superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of the anionic dye bromophenol blue (BPB) from contaminated water. The fabricated SPIONs, azo dye, and ADFS adsorbent were characterized with FTIR and UV-vis absorption spectroscopy, 1HNMR spectroscopy, mass spectrometry, SEM imaging, dynamic light scattering (DLS), zeta potential measurements, vibrating sample magnetometry, thermogravimetric analysis, differential thermal analysis, and X-ray diffraction analysis. DLS measurements showed a particle size of 46.1 and 176.5 nm for the SPIONs and the ADFS, respectively. The adsorbent exhibited an adsorption capacity of 7.43 mg g-1 and followed the pseudo-second-order kinetics model (r2 = 0.9981). The ADFS could efficiently remove BPB from water after stirring for 120 minutes at room temperature and pH 2. The adsorption process was proved to occur via physisorption, as revealed by the Freundlich isotherm (n = 1.82 and KF = 11.5). Thermodynamic studies implied that the adsorption is spontaneous (-8.03 ≤ ΔG ≤ -0.58 kJ mol-1) and enthalpy-driven might take place via van der Waals interactions and/or hydrogen bonding (ΔH = -82.19 kJ mol-1 and ΔS = -0.24 kJ mol-1 K-1).

Fluorescent molecularly imprinted polymer nanocomposite for solid-phase extraction and fluorimetric determination of hydrochlorothiazide

We report herein a fluorescent molecularly imprinted polymer (FMIP) for the solid-phase extraction (SPE) and fluorimetric determination of hydrochlorothiazide (HCTZ) in water. The FMIP is based on fluorescent polystyrene nanoparticles embedded within a molecularly imprinted polyaniline (PANI) matrix. The operational adsorption parameters such as the initial HCTZ concentration, incubation time and the solution pH were found to influence the removal efficiency. At optimum conditions, a high adsorption capacity of the FMIP was found (2.08 mg g-1). Evidence of the adsorption process was confirmed by the change in the FMIP physicochemical properties measured by FTIR absorption spectroscopy and electron microscopy. Based on the regression R2 values and the consistently low values of the adsorption statistical error functions, equilibrium data were best fitted to both Freundlich and Temkin isotherms. Moreover, the pseudo-second-order kinetic model described the adsorption kinetics, and the mechanism of the adsorption process was explained by the intraparticle diffusion model. Upon studying adsorption thermodynamics, negative ΔG values (-26.18 kJ mol-1 at room temperature) were obtained revealing that the adsorption process is spontaneous. Interestingly, the maximum adsorption capacity was obtained at 298 K, pH 7.0, and using a high HCTZ concentration, thus revealing the suitability of the proposed FMIP for easy and fast SPE of HCTZ. The FMIP showed an imprinting factor of 1.19 implying the selectivity over the corresponding FNIP. Eventually, the proposed FMIP was successfully applied to the spectrofluorimetric determination of HCTZ in aqueous samples with %recovery values close to 100%.

Do silver/hydroxyapatite and zinc oxide nano-coatings improve inflammation around titanium orthodontic mini-screws? In vitro study

BACKGROUND

Overcoming the failure percentage of orthodontic mini-screws (OMSs), which is about 30% of overall orthodontic cases, especially in malocclusion treatment that requires orthopaedic heavy forces, is a great challenge. Bacterial infections, soft tissue and bone inflammation, and weak connections between bones and the OMS surface are among the main causalities of this failure.

OBJECTIVE

The aim of the study is to evaluate in vitro the microbiological activities of the deposited nanomaterials (Silver/hydroxyapatite nanoparticles (Ag/HA NPs) and zinc oxide nanoparticles (ZnO NPs)) in terms of microbial inhibition. In addition, the in-vitro cytotoxicity and cytocompatibility of the synthesized nano-coatings prior to their in-vivo application in animal models were tested on four types of cells, namely, fibroblasts, osteocytes, osteoblasts, and oral epithelial cells.

MATERIALS AND METHODS

Ag/HA NPs and ZnO NPs were built up onto the surface of titanium OMSs by electrochemical deposition. This electrochemical deposition was performed on 50 orthodontic mini screws and the deposited materials were characterized with the aid of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) analysis, X-ray Diffraction (XRD) and nano-scratch test. In addition, the microbiological activities of the deposited nanomaterials were explored in vitro in terms of microbial inhibition. Furthermore, the cytotoxicity and cytocompatibility were tested on four types of cells, namely, fibroblasts, osteocytes, osteoblasts and oral epithelial cells.

RESULTS

SEM images revealed spherical Ag NPs in the range of 40-70nm in diameter, rod-shaped HA NPs and porous scaly ZnO NPs on the surface of the OMSs. XRD analysis confirmed the crystal structures of AgNPs, HA NPs, and ZnO NPs. ZnO NPs coated OMS had the highest antimicrobial activity than Ag/HA coated OMS against Gram-positive, Gram-negative and fungal strains. Moreover, after incubation, the decrease in the number of bacterial colonies was significant with ZnO and Ag/HA nanoparticles (with the greatest decrease for the former), due to the potent antibacterial effect of nanoparticles against Escherichia coli and Enterococcus faecalis. Moreover, ZnO NPs-coated OMSs showed a better cytocompatibility with oral epithelium, bone cells, and fibroblasts compared to Ag/HA NPs.

CONCLUSION

The suggested nanocoating is a promising strategy to overcome the development of an inflammatory zone around the fixed OMSs.

Wet Electrospun Nanofibers-Fortified Gelatin/Alginate-Based Nanocomposite as a Single-Dose Biomimicking Skin Substitute

We report the development and evaluation of a series of well-designed single-dose extracellular matrix (ECM)-mimicking nanofibers (NFs)-reinforced hydrogel (HG)-based skin substitute for wound healing. The HG matrix of the proposed skin substitute is composed of gelatin (GE) and sodium alginate (SA), and incorporates hyaluronic acid (HA) as a key component of the natural ECM, as well as the antimicrobial Punica granatum extract (PE). This HG nanocomposite was cross-linked by the biocompatible N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC) cross-linker, and was reinforced with fragmented trans-ferulic acid (FA)-loaded cellulose acetate/polycaprolactone (PCL/CA) NFs. The NFs were obtained via wet electrospinning into a poly(vinyl alcohol) (PVA) coagulating solution to closely resemble the porous structure of the ECM fibers, which facilitates cell migration, attachment, and proliferation. The proposed design of the skin substitute allows adjustable mechanical characteristics and outstanding physical properties (swelling and biodegradability), as well as an excellent porous microstructure. The developed skin substitutes were characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and electron microscopy. In addition, the biodegradability, biocompatibility, bioactivity, mechanical, and in vitro drug release characteristics were investigated. Moreover, an in vivo excisional full-thickness defect model was conducted to assess skin regeneration and healing effectiveness. The average diameters of the plain and FA-loaded NFs are 210 ± 12 nm and 452 ± 25 nm, respectively. The developed ECM-mimicking skin substitutes demonstrated good antibacterial activity, free-radical scavenging activity, cytocompatibility, porosity, water absorption ability, and good biodegradability. In vivo application of the ECM-mimicking skin substitutes revealed their excellent wound-healing activity and their suitability for single-dose treatment of deep wounds with reducing the wound diameter to 0.95 mm after 15 days of treatment. Moreover, the histological investigation of the wound area demonstrated that the applied skin substitutes have not only enhanced the wound healing progress, but also can participate in improving the quality of the regenerated skin in the treated area via facilitating collagen fibers regeneration and deposition.

Azo-functionalized superparamagnetic Fe3O4 nanoparticles: an efficient adsorbent for the removal of bromocresol green from contaminated water

Water contamination is regarded as one of the world's worst tragedies owing to the continual depletion of water resources suitable for drinking and agriculture. Researchers have recently been interested in developing novel and more effective adsorbents for wastewater purification. We report herein a magnetic adsorbent nanomaterial for the removal of the anionic dye bromocresol green (BCG) from wastewater. The adsorbent is based on superparamagnetic iron oxide (cubic Fe₃O₄) nanoparticles (SPIONs) coated with a high-molecular-weight azo dye synthesized via diazo coupling of vitamin B1 with a trisubstituted benzene derivative. The proposed adsorbent was characterized using scanning electron microscopy, FTIR and ¹H-NMR spectroscopy, mass spectrometry, dynamic light scattering, vibrating sample magnetometry, thermal analysis, and X-ray diffraction crystallography. At room temperature and pH 2.0, the synthesized adsorbent showed an average particle size of 65.9 ± 8.0 nm, a high magnetization saturation (65.58 emu g⁻¹), a high equilibrium adsorption capacity (36.91 mg g⁻¹). Adsorption of BCG was found to take place via a physisorption mechanism and followed a pseudo-second-order rate kinetics. Thermodynamic studies revealed that the adsorption process is enthalpy driven by hydrogen bonding and/or van der Waals interactions. After treating water samples with the suggested adsorbent, it can be easily removed from water using a strong external magnetic field.

An efficient adsorbent based on azo-dye-coated superparamagnetic Fe₃O₄ nanoparticles was synthesized for the removal of the anionic dye, bromocresol green, from wastewater.

Matrix-dispersed magnetic molecularly-imprinted polyaniline for the effective removal of chlorpyrifos pesticide from contaminated water

We report a new adsorbent nanocomposite material based on matrix-dispersed superparamagnetic iron oxide nanoparticles (SPIONs) in molecularly-imprinted polyaniline for the removal of chlorpyrifos (CPF), a hazardous organophosphate pesticide, from water. The synthesized magnetic molecularly-imprinted polymer (MMIP) was characterized by FTIR spectroscopy, XRD, magnetic susceptibility, DLS, zeta potential measurement, SEM and high-resolution TEM imaging. The average size of the naked SPIONs ranges from 15 to 30 nm according to the high-resolution TEM analysis. Moreover, the adsorption kinetics, thermodynamic parameters (ΔG, ΔH and ΔS), adsorption isotherms and rebinding conditions were investigated in detail. The proposed MMIP has an imprinting factor of 1.64. In addition, it showed a high experimental adsorption capacity of 1.77 mg g⁻¹ and a removal efficiency of nearly 80%. The fabricated MMIP material demonstrated excellent magnetic susceptibility allowing for easy separation using an external magnetic field. The adsorption mechanism of CPF onto the MMIP adsorbent followed the second-order kinetics model and fitted to the Temkin adsorption isotherm. By studying the adsorption thermodynamics, negative ΔG values (−1.955 kJ mol⁻¹ at room temperature) were obtained revealing that the adsorption process is spontaneous. Furthermore, the maximum adsorption capacity was obtained at room temperature (ca. 303 K), neutral pH and using a high CPF concentration.

An efficient magnetic molecularly-imprinted polymer adsorbent for removal of chlorpyrifos organophosphate pesticide from water is reported.

Deacetylated cellulose acetate nanofibrous dressing loaded with chitosan/propolis nanoparticles for the effective treatment of burn wounds

Every year, about 1 out of 9 get burnt in Egypt, with a mortality rate of 37%, and they suffer from physical disfigurement and trauma. For the treatment of second-degree burns, we aim at making a smart bandage provided with control of drug release (using chitosan nanoparticles) to enhance the healing process. This bandage is composed of natural materials; namely, cellulose acetate (CA), chitosan, and propolis (bee resin) as the loaded drug. Cellulose acetate nanofibers were deacetylated by NaOH after optimizing the reaction time and the concentration of NaOH solution, and the product was confirmed with FTIR analysis. Chitosan/propolis nanoparticles were prepared by ion gelation method with size ranging from 100 to 200 nm and a polydispersity index of 0.3. Chitosan/propolis nanoparticles were preloaded in the CA solution to ensure homogeneity. Loaded deacetylated cellulose nanofibers have shown the highest hydrophobicity measured by contact angle. Cytotoxicity of propolis and chitosan/propolis nanoparticles were tested and the experimental IC₅₀ value was about 137.5 and 116.0 μg/mL, respectively, with p-value ≤0.001. In addition, chitosan/propolis nanoparticles loaded into cellulose nanofibers showed a cell viability of 89.46% in the cell viability test. In-vivo experiments showed that after 21 days of treatment with the loaded nanofibers repairing of epithelial cells, hair follicles and sebaceous glands in the skin of the burn wound were found in albino-mice model.

Boosting the mechanical strength and solubility-enhancement properties of hydroxypropyl-β-cyclodextrin nanofibrous films

2-hydroxypropyl-β-cyclodextrin (HPβCD) nanofiber films have high surface-to-volume ratio and show high dissolution rate of hydrophobic drugs. However, the solubility-enhancement effect of HPβCD films may not be enough to include an effective dose in a sublingually administrable film. Moreover, unmodified HPβCD films are very brittle and difficultly transported and/or handled. So, the addition of polyethylene glycol (PEG) as a plasticizer was suggested to improve their ultimate tensile strength (UTS) and solubilization of hydrophobic drugs. Accordingly, six nanofiber films were developed and characterized, using three molecular weights of PEG (400, 1500 and 6000 Da) with two concentrations each (1:100 and 2:100 PEG:HPβCD), in addition to the unmodified HPβCD nanofibrous film. The results revealed that adding 1:100 of PEG 400 increases the UTS (∼2-fold) and the average fiber diameter (AFD) (∼3-fold). Moreover, the addition of PEG 400 significantly increased the solubility of two hydrophobic model drugs; coumarin (up to 7.7-fold of the original solubility) and 2-nitroimidazole (up to 1.6-fold of the original solubility). However, with higher PEG concentration/molecular weight, both AFD and UTS of the films decreased. On the other hand, it was noted that the solubility of the two model drugs decreased upon using 1500-Da PEG, and then increased with 6000-Da PEG.

Chitosan/Gold Hybrid Nanoparticles Enriched Electrospun PVA Nanofibrous Mats for the Topical Delivery of Punica granatum L. Extract: Synthesis, Characterization, Biocompatibility and Antibacterial Properties

Purpose

Intending to obtain Punica granatum L. extract (PE)-loaded drug delivery system of better impact and biomedical applicability, the current study reports the use of crosslinked PVA nanofibers (NFs) as platforms incorporating different amounts of biosynthesized PE-CS-gold nanoparticles (PE-CS-Au NPs).

Methods

PE-conjugated CS-Au nanoparticles (PE-CS-Au NPs) were synthesized via green chemistry approach. The formation of PE-CS-Au NPs was confirmed by UV spectroscopy, DLS, SEM and STEM. PE-CS-Au NPs were then dispersed into polyvinyl alcohol (PVA) solution at different ratios, where the optimized ratios were selected for electrospinning and further studies. Crosslinking of PE-CS-Au NPs loaded PVA nanofibers (NFs) was performed via glutaraldehyde vapor. The morphology, chemical compositions, thermal stability and mechanical properties of PE-CS-Au NPs loaded NFs were evaluated by SEM, FTIR and DSC. Swelling capacity, biodegradability, PE release profiles, release kinetics, antibacterial and cell biocompatibility were also demonstrated.

Results

By incorporating PE-CS-Au NPs at 0.6% and 0.9%, the diameters of the nanofibers decreased from 295.7±83.1 nm in neat PVA to 165.6±43.4 and 147.8±42.7 nm, respectively. It is worth noting that crosslinking and incorporation of PE-CS-Au NPs improved thermal stability and mechanical properties of the obtained NFs. The release of PE from NFs was controlled by a Fickian diffusion mechanism (n value ˂0.5), whereas Higuchi was the mathematical model which could describe this release. The antibacterial activity was found to be directly proportional to the amount of the incorporated PE-CS-Au NPs. The human fibroblasts (HFF-1) showed the highest viability (123%) by seeding over the PVA NFs mats containing 0.9% PE-CS-Au NPs.

Conclusion

The obtained results suggest that the electrospun PVA NFs composites containing 0.9% PE-CS-Au NPs can be used as antibacterial agents against antibiotic-resistant bacteria, and as suitable scaffolds for cell adhesion, growth and proliferation of fibroblast populations.

Microwave-Assisted One Pot Three-Component Synthesis of Novel Bioactive Thiazolyl-Pyridazinediones as Potential Antimicrobial Agents against Antibiotic-Resistant Bacteria

Pyridazine and thiazole derivatives have various biological activities such as antimicrobial, analgesic, anticancer, anticonvulsant, antitubercular and other anticipated biological properties. Chitosan can be used as heterogeneous phase transfer basic biocatalyst in heterocyclic syntheses. Novel 1-thiazolyl-pyridazinedione derivatives were prepared via multicomponent synthesis under microwave irradiation as ecofriendly energy source and using the eco-friendly naturally occurring chitosan basic catalyst with high/efficient yields and short reaction time. All the prepared compounds were fully characterized by spectroscopic methods, and their in vitro biological activities were investigated. The obtained results were compared with those of standard antibacterial/antifungal agents. DFT calculations and molecular docking studies were used to investigate the electronic properties and molecular interactions with specific microbial receptors.

Matrix-dispersed PEI-coated SPIONs for fast and efficient removal of anionic dyes from textile wastewater samples: Applications to triphenylmethanes

Textile industries produce a massive amount of wastewater that should be cleaned from toxic substances such as fats, colors and any chemicals used during the production steps. Water-treatment methods should be facile, economic, fast and efficient. Here, we report the synthesis, characterization and application of matrix-dispersed superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of anionic dyes from wastewater released from textile industrial plants. The matrix-dispersed SPIONs were synthesized via a solvothermal method in which a polyethyleneimine (PEI) shell was deposited onto SPIONs in order to add positive charges to their surfaces. TEM images revealed that the size of PEI-coated and uncoated SPIONs is 30-50 and 15-30 nm, respectively. Moreover, TEM images depicted that the as synthesized PEI-coated SPIONs show matrix-dispersed structures. Furthermore, the particle size obtained with DLS measurements was found to be 87.93 and 158.9 nm for uncoated and PEI-coated SPIONs, respectively. Bromophenol blue (BPB) and bromocresol green (BCG), two triphenylmethanes, were used as model anionic dyes. FTIR spectroscopy revealed the interaction between the PEI surface coating and the anionic dyes. The apparent ζ-potential measurements showed that the surface negative charges decreased from -13.5 to -4.03 mV upon coating with PEI. In order to investigate the anionic dyes removal/entrapment efficiency of SPIONs, a new derivative visible spectrophotometric method was developed for the simultaneous quantification of BPB and BCG before and after treatment where the linear ranges were 6.98-27.9 and 6.70-26.8 μg/mL and the recovery values were in the ranges of 98.10-101.7% and 99.55-104.8% for BCG and BPB, respectively. It was found that the uptake/adsorption capacity of PEI-coated SPIONs is ca.15.5 and 11.3 mg/g for BCG and BPB, respectively. The calculated thermodynamic parameters for the adsorption of BCG (ΔH = 37.08 J/mol and ΔS = 120.89 J/mol K) and BPB (ΔH = 181.26 J/mol and ΔS = 596.46 J/mol K) and the negative ΔG values indicate that the adsorption is thermodynamically favored. The adsorption processes were found to follow the pseudo-second-order kinetic model with r² values of 0.9982 and 0.9956 for BCG and BPB, respectively.

User-friendly lab-on-paper optical sensor for the rapid detection of bacterial spoilage in packaged meat products

A lab-on-paper colorimetric sensor for detection and quantification of bacterial meat spoilage is reported.

Artichoke extracts in cancer therapy: do the extraction conditions affect the anticancer activity?

Background

Artichoke is an edible plant that is grown in the Mediterranean region and is known for its antimicrobial, antifungal, antibacterial, antioxidant and anticancer activities. Different artichoke extraction methods can impressively affect the nature as well as the yield of the extracted components.

Main body

The different methods of artichoke extraction and the influence of the extraction conditions on the extraction efficiency are summarized herein. In addition, cancer causalities and hallmarks together with the molecular mechanisms of artichoke active molecules in cancer treatment are also discussed. Moreover, a short background is given on the common types of cancer that can be treated with artichoke extracts as well as their pathogenesis. A brief discussion of the previous works devoted to the application of artichoke extracts in the treatment of these cancers is also given.

Conclusion

This review article covers the extraction methods, composition, utilization and applications of artichoke extracts in the treatment of different cancers.

Tailoring the electrochemical properties of 2D-hBN via physical linear defects: physicochemical, computational and electrochemical characterisation

Monolayer hexagonal-boron nitride films (2D-hBN) are typically reported within the literature to be electrochemically inactive due to their considerable band gap (ca. 5.2-5.8 eV). It is demonstrated herein that introducing physical linear defects (PLDs) upon the basal plane surface of 2D-hBN gives rise to electrochemically useful signatures. The reason for this transformation from insulator to semiconductor (inferred from physicochemical and computational characterisation) is likely due to full hydrogenation and oxygen passivation of the boron and/or nitrogen at edge sites. This results in a decrease in the band gap (from ca. 6.11 to 2.36/2.84 eV; theoretical calculated values, for the fully hydrogenated oxygen passivation at the N or B respectively). The 2D-hBN films are shown to be tailored through the introduction of PLDs, with the electrochemical behaviour dependent upon the surface coverage of edge plane-sites/defects, which is correlated with electrochemical performance towards redox probes (hexaammineruthenium(iii) chloride and Fe2+/3+) and the hydrogen evolution reaction. This manuscript de-convolutes, for the first time, the fundamental electron transfer properties of 2D-hBN, demonstrating that through implementation of PLDs, one can beneficially tailor the electrochemical properties of this nanomaterial.

Exploring the influence of particle shape and air velocity on the flowability in the respiratory tract: a computational fluid dynamics approach

Dry powder inhalers (DPIs) are considered a main drug delivery system through pulmonary route. The main objective of this work is to study the flow of differently shaped microparticles in order to find the optimum shape of drug particles that will demonstrate the best flow to the deep lung. The flowability of particles in air or any fluid depends particularly on the drag force which is defined as the resistance of the fluid molecules to the particle flow. One of the most important parameters that affect the drag force is the particles' shape. Computational simulations using COMSOL Multi Physics 5.2 software were performed for investigating the particles flow in the air pathways of lung, and the drag force was calculated for different particles shapes. This was accomplished by screening a set of 17 possible shapes that are expected to be synthesized easily in the micro-scale. In addition, the macro-scale behavior of the investigated shapes was also simulated so as to compare the behavior of the flowing particles in both cases. A very big difference was found between the behavior of particles' flow in the micro and macro scales, but a similar behavior can be obtained if the flow velocity of the microparticles is very high. It was also found that the micro-triangle with aspect ratio 2:1 has the least drag force in both deep and upper lung; so, it should be the shape of choice during the process of particle synthesis for pulmonary drug delivery.

H-point standard addition for simultaneous reagent-free spectrophotometric determination of B1 and B6 vitamins

Vitamin deficiency is a main cause of many disorders and diseases that cannot be treated without using dietary supplements and multivitamin medications. We present here a UV-spectrophotometric method for simultaneous assay of two of the widely used vitamins, thiamine hydrochloride (vitamin B1) and pyridoxine hydrochloride (vitamin B6). The method is based on H-point standard addition to estimate the vitamins under study in their pure solutions and multivitamin ampoules by measuring the absorption of the mixture at 283 and 298 nm allowing its application in quality control laboratories. The work summarizes the theoretical basis of the H-point standard addition method. Moreover, a guide for the selection of the two wavelengths at which the calibration curves are constructed is given in this investigation. The linear ranges of the calibration graphs are 6.75-67.5 and 2.06-20.56 μg/mL for thiamine and pyridoxine, respectively. Correlation coefficients (r²) were found to be 0.9990 and 0.9899 at 283 nm and 0.9855 and 0.9995 at 298 nm for vitamin B1 and vitamin B6, respectively. Oscillator strength (f), transition dipole moment (μ) and resonance energy (R_N) were calculated. The method was successfully applied for dual determination of the vitamins in their pure solutions and multivitamin ampoules with recovery values ranging from 98.41 to 102.6 and from 95.39 to 104.9% for thiamine and pyridoxine, respectively. The accuracy and precision of the proposed method is obvious from the low relative standard deviation values which are not more than 1.19%.

Exploring the electrochemical performance of graphite and graphene paste electrodes composed of varying lateral flake sizes

We report the fabrication, characterisation (SEM/EDX, TEM, XRD, XPS and Raman spectroscopy) and electrochemical properties of graphite and graphene paste electrodes with varying lateral flake sizes. The fabricated paste electrodes are electrochemically analysed using both outer-sphere and inner-sphere redox probes, namely; hexaammineruthenium(iii) chloride, N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), potassium ferrocyanide(ii) and ammonium ferrous(ii) sulphate. Upon comparison of different graphite paste electrodes, a clear correlation between the lateral flake sizes (La), ranging from 1.5 mm-0.5 μm, and electrochemical activity (heterogeneous electron transfer (HET) kinetics) is evident, where an improvement in the HET is observed at smaller lateral flake sizes. We infer that the beneficial response evident when employing laterally smaller flakes is due to an increased number of edge plane like-sites/defects available upon the electrode surface, facilitating electron transfer. Interestingly, given that the overall lateral flake sizes of the graphenes utilised (10.0-1.3 μm) were significantly smaller than those studied previously, an improvement in HET kinetics was also evident with the reduction of lateral flake size; the extent to which is redox-probe dependent. Improvements are observed up to a distinct point, termed the 'lateral size threshold' (ca. ≤2 μm) where the electrochemical reversible limit is approached. Further support is provided from density functional theory (DFT), exploring the electronic structure (i.e. HOMO-LUMO) as a function of flake size, which demonstrates that the coverage of edge plane like-sites/defects comprising the geometric structure of the relatively small graphene flakes is such that effectively the entire flake has become electrochemically active. In this study, the importance of lateral flake size with respect to electrochemical reactivity at carbon-based electrodes has been demonstrated alongside a structural relationship upon HET performance, a phenomenon that has not previously been described in the literature. Such work is both highly important and informative for the field of electrochemistry and electrode performance, with potential implications in a plethora of areas, ranging from novel renewable energy sources to electroanalytical sensing platforms.

In vitro drug interaction of levocetirizine and diclofenac: Theoretical and spectroscopic studies

Levocetirizine dihydrochloride is known to interact with some anti-inflammatory drugs. We report here a comprehensive integrated theoretical and experimental study for the in vitro drug interaction between levocetirizine dihydrochloride (LEV) and diclofenac sodium (DIC). The interaction of the two drugs was confirmed by the molecular ion peak obtained from the mass spectrum of the product. Moreover, FTIR and ¹HNMR spectra of the individual drugs and their interaction product were inspected to allocate the possible sites of interaction. In addition, quantum mechanical DFT calculations were performed to search for the interaction sites and to verify the types of interactions deduced from the spectroscopic studies such as charge-transfer and non-bonding π-π interactions. It was found that the studied drugs interact with each other in aqueous solution via four types of interactions, namely, ion-pair formation, three weak hydrogen bonds, non-bonding π-π interactions and charge-transfer from DIC to LEV.

Experimental and quantum mechanical studies on the ion-pair of levocetirizine and bromocresol green in aqueous solutions

In the present work, levocetirizine dihydrochloride (LEV) was found to interact with bromocresol green (BCG) via ion-pair formation. UV-vis and FTIR spectroscopy were used to validate the data obtained from quantum mechanical calculations (QMC). The electrostatic potential maps show that the reaction is preferred through the interaction of the sulfonic acid group of BCG and the quaternary ammonium group of LEV. The optimized geometry of the product shows that there are six different intermolecular hydrogen bonds between the studied molecules resulting from the ionic attraction between the oppositely charged groups. The UV-vis spectra suggest the formation of an ion-pair. This finding is contradicting with the previous charge-transfer hypothesis.