Phosphate-buffered Saline Medium Research Articles

Degradable Cell-Adhesive Hybrid Hydrogels by Cross-Linking of Gelatin with Poly(2-isopropenyl-2-oxazoline).

This study focused on the cross-linking of poly(2-isopropenyl-2-oxazoline) (PiPOx) with gelatin to obtain strong, degradable hybrid hydrogels with good cell adhesion. The molecular weight and concentration of PiPOx and the PiPOx-to-gelatin ratio were varied to adjust the mechanical and swelling properties of the hybrid hydrogels. The swelling degree of PiPOx-gelatin hydrogels in water ranged between 1260 and 810%, with the corresponding Young's compressive moduli ranging from 77 to 215 kPa. Rheological measurements demonstrated the mechanical stability of the hydrogels. The hydrogels exhibited substantial degradation in Dulbecco's phosphate-buffered saline (DPBS) and cell culture medium within several weeks, indicating their degradability and responsiveness. The cell adhesion assay with primary human foreskin fibroblasts revealed the hybrid hydrogels are noncytotoxic and support cell attachment and proliferation. These strong hydrogels thus show excellent potential as biomedical cell scaffolds, combining the tunability and strength of PiPOx hydrogels with gelatin's cell-interactive properties while the ester-containing cross-links provide tunable degradability.

Wireless implantable bioelectronics with a direct electron transfer lactate enzyme for detection of surgical site infection in orthopaedics

Periprosthetic infection is one of the most devastating complications following orthopaedic surgery. Rapid detection of an infection can change the treatment pathway and improve outcomes for the patient. In here, we propose a miniaturized lactate biosensor developed on a flexible substrate and integrated on a small-form bone implant to detect infection. The methods for lactate biosensor fabrication and integration on a bone implant are fully described within this study. The system performance was comprehensively electrochemically characterised, including with L-lactate solutions prepared in phosphate-buffered saline and culture medium, and interferents such as acetaminophen and ascorbic acid. A proof-of-concept demonstration was then conducted with ex vivo ovine femoral heads incubated with and without exposure to Staphylococcus epidermidis. The sensitivity, current density and limit-of-detection levels achieved by the biosensor were 1.25 μA mM−1, 1.51 μA.M−1.mm−2 and 66 μM, respectively. The system was insensitive to acetaminophen, while sensitivity to ascorbic acid was half that of the sensitivity to L-lactate. In the ex vivo bone model, S. epidermidis infection was detected within 5 h of implantation, while the control sample led to no change in the sensor readings. This pioneering work demonstrates a pathway to improving orthopaedic outcomes by enabling early infection diagnosis.

Mechanical Transfer of Black Phosphorus on a Silk Fibroin Substrate: A Viable Method for Photoresponsive and Printable Biomaterials.

Despite the technological importance of semiconductor black phosphorus (BP) in materials science, maintaining the stability of BP crystals in organic media and protecting them from environmental oxidation remains challenging. In this study, we present the synthesis of bulk BP and the exploitation of the viscoelastic properties of a regenerated silk fibroin (SF) film as a biocompatible substrate to transfer BP flakes, thereby preventing oxidation. A model based on the flow of polymers revealed that the applied flow-induced stresses exceed the yield stress of the BP aggregate. Raman spectroscopy was used to investigate the exfoliation efficiency as well as the environmental stability of BP transferred on the SF substrate. Notably, BP flakes transferred to the SF substrate demonstrated improved stability when SF was dissolved in a phosphate-buffered saline medium, and in vitro cancer cell viability experiments demonstrate the tumor ablation efficiency under visible to near-infrared (Vis-nIR) radiation. Moreover, the SF and BP-enriched SF (SF/BP) solution was shown to be processable via extrusion-based three-dimensional (3D) printing. Therefore, this work paves the way for a general method for the transferring of BP on natural biodegradable polymers and processing them via 3D printing toward novel functionalities and complex shapes for biomedical purposes.

Tribological and electrochemical corrosion behavior of binary Mg–3Zn novel hybrid composites for biodegradable implant applications

Abstract The present research work is focused on analyzing the tribological and corrosion impacts of introducing a new metal/bioceramic (Ti/HA) compound into the matrix of the Mg–3Zn alloy. The hybrid composites were developed using the squeeze casting method. The density, microhardness, and microstructure of the developed composite materials were examined. A pin-on-disk tribology meter was used to conduct the tribological study under a phosphate-buffered saline (PBS) lubricating medium. Studies on electrochemical corrosion were carried out in the PBS medium. Incorporating hybrid Ti/HA particles into the Mg–3Zn alloy matrix significantly increased the density and microhardness of the composites. Optical microscopy demonstrates a refined grain size and uniform distribution of reinforced particles, showcasing improved structural integrity. Scanning electron microscopy analysis further confirms the α-Mg and β-Mg–Zn phases. According to the findings of wear tests, the Ti/HA inclusion in the Mg–3Zn (MZ0) matrix increased the resistance to wear behavior. Abrasion, delamination, oxide layer formation, and severe delamination features were observed at the worn surfaces. Abrasive wear happened along with all other wear mechanisms and served as a wear initiator. Potentiodynamic polarization experiments revealed that the corrosion resistance of hybrid composites was increased with the inclusion of 1.5 % HA.

Development and validation of UV–Vis spectrophotometry-colorimetric method for the specific quantification of rivastigmine tartrate from separable effervescent microneedles: Ex vivo and in vivo applications in complex biological matrices

Rivastigmine Tartrate is an acetylcholinesterase inhibitor commonly used in Alzheimer treatment. Due to its hydrophilicity, short plasma elimination half-time, and poor blood-brain barrier penetration, developing a new drug delivery system for RT administration is essential. Accordingly, microneedles offer several advantages and could be a promising drug delivery system for RT administration. One of those types of MNs with numerous advantages is separable-effervescent microneedles. To support the formulation development, an analytical method using UV–Vis spectrophotometry was validated in phosphate buffered saline media and various biological matrices, such as rat skin, brain, and plasma to measure the amount of RT in the SEMNs preparations. The developed analytical method was validated under ICH guidelines. The results showed that the instrument could specifically detect the RT in the preparations without being interfered with by other compounds. The calibration curves in various biological matrices were linear ≥ 0.9985. The LOD and LLOQ values of the PBS media biological matrices were found to be 1.5 and 4.8 µg/mL, 1.2 and 3.7 µg/mL, 0.42 and 1.27 µg/mL, and 0.38 and 1.16 µg/mL, respectively. All the accuracy and precision values of this developed method were within acceptable ranges. Additionally, the extraction recovery was prominent after undergoing the protein precipitation process. As a result, the analytical method was proven to be valid and was successfully applied to quantify the amount of RT in the SEMNs formulation, in vitro and ex vivo permeation, along with in vivo pharmacokinetic studies.

Production and Characterization of Bioactive and Antimicrobial Titanium Oxide Surfaces with Silver Nanoparticles and a Poly(lactic Acid) Microfiber Coating

Silver nanoparticles (AgNp) were deposited on highly porous TiO2 surfaces by the dripping of a colloidal AgNp solution to provide antimicrobial activity. Micro-porous TiO2 surfaces were obtained on commercially pure titanium by micro-arc oxidation in an electrolyte containing Ca and P precursors. In addition, as silver can be toxic to cells, these surfaces were uniformly covered with the biocompatible and bioresorbable poly(lactic acid) (PLA) polymer by electrospinning, aiming at promoting a controlled release of silver ions to the medium. The resulting AgNp-containing surfaces were characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD), and in vitro assays were performed to evaluate their antimicrobial activity and bioactivity. Tests revealed that the surfaces showed antimicrobial activity against Staphylococcus aureus, with better results for the surfaces without PLA. However, all the surfaces presented good biocompatibility in assays with mouse MC3T3-E1 pre-osteoblasts, and greater cell differentiation for the polymer-coated surfaces. Finally, the PLA ultrafine fibers electrospun on the TiO2/AgNp surfaces allowed a controlled release of silver ions in the phosphate-buffered saline (PBS) medium.

Facile modification of polyvinylidene fluoride membrane for enhancing dialysis performance: sulfonation, adding polyethylene glycol and tuning coagulation bath temperature

Modifications were successfully carried out on the polyvinylidene fluoride (PVDF) flat sheet membrane, involving the sulfonation and adding polyethylene glycol (PEG), along with variations in the coagulation bath temperature (CBT). The primary objective of these modifications was to examine their impact on the physicochemical characteristics of the membrane and its permeability to a creatinine solution. The findings revealed that the sulfonated PVDF/PEG membrane, printed at a temperature of 30 °C, displayed substantial increases in porosity, hydrophilicity, water uptake and swelling degree. It is important to note that modifications to the PVDF membrane led to a reduction in thermal stability and an increase in creatinine transport efficiency. For the unmodified PVDF membranes, the clearance values for creatinine in phosphate buffer and phosphate buffer saline media were 0.43 (Transport = 28.65%) and 0.42 mg/dL (Transport = 28.05%), respectively. Conversely, the highest creatinine clearance values were achieved by the SPP30 membrane (sulfonated PVDF/PEG-CBT 30 °C), measuring 0.64 mg/dL (Transport = 42.81%) for creatinine and 0.60 mg/dL for urea (Transport = 39.66%). These results indicate that the sulfonated PVDF/PEG membrane exhibits strong potential for use in hemodialysis applications.

Biomimetic Inorganic Nanovectors as Tumor-Targeting Theranostic Platform against Triple-Negative Breast Cancer.

Mesoporous silicon nanoparticles (PSi NPs) are promising platforms of nanomedicine because of their good compatibility, high payload capacities of anticancer drugs, and easy chemical modification. Here, PSi surfaces were functionalized with bisphosphonates (BP) for radiolabeling, loaded with doxorubicin (DOX) for chemotherapy, and the NPs were coated with cancer cell membrane (CCm) for homotypic cancer targeting. To enhance the CCm coating, the NP surfaces were covered with polyethylene glycol prior to the CCm coating. The effects of the BP amount and pH conditions on the radiolabeling efficacy were studied. The maximum BP was (2.27 wt%) on the PSi surfaces, and higher radiochemical yields were obtained for 99mTc (97% ± 2%) and 68Ga (94.6% ± 0.2%) under optimized pH conditions (pH = 5). The biomimetic NPs exhibited a good radiochemical and colloidal stability in phosphate-buffered saline and cell medium. In vitro studies demonstrated that the biomimetic NPs exhibited an enhanced cellular uptake and increased delivery of DOX to cancer cells, resulting in better chemotherapy than free DOX or pure NPs. Altogether, these findings indicate the potential of the developed platform for cancer treatment and diagnosis.

Physiological fluid-assisted nanostructured NbN@Cu foam supercapacitor towards flexible and biocompatible energy storage applications

As the demand for implantable and wearable electronic devices is becoming prevalent, developing flexible and biocompatible energy storage is imperative. In this study, we have successfully fabricated a flexible and biocompatible supercapacitor. We used DC magnetron sputtering to deposit niobium nitride (NbN) on the copper foam (Cu foam) substrate to fabricate NbN@Cu foam. The fabricated NbN@Cu foam electrodes demonstrate a highly porous structure with uniform distribution of NbN on copper foam substrate. The in-vitro biocompatibility of the electrode was assessed using cell viability studies on the L929 fibroblast cells. The biocompatibility tests revealed no significant cytotoxic effects on the cell lines. The supercapacitor device demonstrated excellent electrochemical stability and efficient electrochemical performance (specific capacitance of 10.772 Fg−1 and 86.8 % retention after 5000 cycles). The device can operate in various physiological fluids (phosphate buffer saline and cell culture medium). These findings strongly suggest that the NbN@Cu foam supercapacitor holds significant promise as a flexible, and biocompatible energy storage device that can be used in a wide range of applications in wearable and implantable electronic devices.

Development and In Vitro-In Vivo Correlation Evaluation of IMM-H014 Extended-Release Tablets for the Treatment of Fatty Liver Disease.

This study aimed to develop extended-release tablets containing 25 mg IMM-H014, an original drug formulated by a direct powder pressing method based on pharmaceutical-grade hydrophilic matrix polymers such as hydroxypropyl methylcellulose, to establish an in vitro-in vivo correlation (IVIVC) to predict bioavailability. The tablets' mechanical properties and in vitro and in vivo performance were studied. The formulation was optimized using a single-factor experiment and the reproducibility was confirmed. The in vitro dissolution profiles of the tablet were determined in five dissolution media, in which the drug released from the hydrophilic tablets followed the Ritger-Peppas model kinetics in 0.01 N HCl medium for the first 2 h, and in phosphate-buffered saline medium (pH 7.5) for a further 24 h. Accelerated stability studies (40 °C, 75% relative humidity) proved that the optimal formulation was stable for 6 months. The in vivo pharmacokinetics study in beagle dogs showed that compared to the IMM-H014 immediate release preparation, the maximum plasma concentration of the extended-release (ER) preparation was significantly decreased, while the maximum time to peak and mean residence time were significantly prolonged. The relative bioavailability was 97.9% based on the area under curve, indicating that the optimal formulation has an obvious ER profile, and a good IVIVC was established, which could be used to predict in vivo pharmacokinetics based on the formulation composition.

Improving Mechanical Properties of Tendon Allograft through Rehydration Strategies: An In Vitro Study.

Allogenic tendons grafts sourced from intrasynovial tendons are often used for tendon reconstruction. Processing is achieved through repetitive freeze-thaw cycles followed by lyophilization. Soaking the lyophilized tendon in saline (0.9%) for 24 h is the standard practice for rehydration. However, data supporting saline rehydration over the use of other hydrating solutions are scant. The purpose of the current study was to compare the effects of different rehydration solutions on biomechanical properties of lyophilized tendon allograft. A total of 36 canine flexor digitorum profundus tendons were collected, five freeze-thaw cycles followed by lyophilization were performed for processing, and then divided into three groups rehydrated with either saline solution (0.9%), phosphate-buffered saline (PBS), or minimum essential medium (MEM). Flexural stiffness, tensile stiffness, and gliding friction were evaluated before and after allograft processing. The flexural moduli in both fibrous and fibrocartilaginous regions of the tendons were measured. After lyophilization and reconstitution, the flexural moduli of both the fibrocartilaginous and non-fibrocartilaginous regions of the tendons increase significantly in the saline and MEM groups (p < 0.05). Compared to the saline and MEM groups, the flexural moduli of the fibrocartilaginous and non-fibrocartilaginous regions of tendons rehydrated with PBS are significantly lower (p < 0.05). Tensile moduli of rehydrated tendons are significantly lower than those of fresh tendons for all groups (p < 0.05). The gliding friction of rehydrated tendons is significantly higher than that of fresh tendons in all groups (p < 0.05). There is no significant difference in either tensile moduli or gliding friction between tendons treated with different rehydration solutions. These results demonstrate that allograft reconstitution can be optimized through careful selection of hydrating solution and that PBS could be a better choice as the impact on flexural properties is lower.

Mitochondria-Targeted COUPY Photocages: Synthesis and Visible-Light Photoactivation in Living Cells.

Releasing bioactive molecules in specific subcellular locations from the corresponding caged precursors offers great potential in photopharmacology, especially when using biologically compatible visible light. By taking advantage of the intrinsic preference of COUPY coumarins for mitochondria and their long wavelength absorption in the visible region, we have synthesized and fully characterized a series of COUPY-caged model compounds to investigate how the structure of the coumarin caging group affects the rate and efficiency of the photolysis process. Uncaging studies using yellow (560 nm) and red light (620 nm) in phosphate-buffered saline medium have demonstrated that the incorporation of a methyl group in a position adjacent to the photocleavable bond is particularly important to fine-tune the photochemical properties of the caging group. Additionally, the use of a COUPY-caged version of the protonophore 2,4-dinitrophenol allowed us to confirm by confocal microscopy that photoactivation can occur within mitochondria of living HeLa cells upon irradiation with low doses of yellow light. The new photolabile protecting groups presented here complement the photochemical toolbox in therapeutic applications since they will facilitate the delivery of photocages of biologically active compounds into mitochondria.

Novel synthesis of BCP cotton-wool-like nanofibrous scaffolds by air-heated solution blow spinning (A-HSBS) technique

Biphasic calcium phosphate (BCP) cotton-wool-like nanofibrous scaffolds are very interesting materials for tissue engineering. Air-heated solution blow spinning (A-HSBS) was a simple and novel strategy developed in this work to obtain this structure. Precursor solutions of calcium nitrate, triethyl phosphate, and polyvinylpyrrolidone (spinning agent) dissolved in water and ethanol were used. The scaffolds were calcined at 800 °C. Part of the samples was stored under restricted atmospheric conditions, while the other part was exposed to ambient conditions for 7 days. The scaffolds were characterized by thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. In vitro assays were performed using simulated body fluid (SBF) and phosphate-buffered saline (PBS) solutions. Results showed the formation of scaffolds constituted by intertwined nanometric fibers. XRD patterns indicated the formation of BCP and CaO. For the sample exposed to air, CaCO3 was formed from the conversion of CaO with atmospheric CO2, producing BCP/CaCO3. After 7 days of immersion in SBF solution, the formation of a homogeneous layer of apatite was more evident on the surface of the BCP/CaCO3 than on the BCP nanofibers. The biodegradability in PBS medium, after 14 days of immersion, showed a mass loss of 21% (pH of 8.3) and 14% for the BCP and BCP/CaCO3 scaffolds (pH of 7.8), respectively. BCP nanofibrous scaffolds can be considered promising candidates for use in bone tissue engineering applications.

Thermal Properties and In Vitro Biodegradation of PLA-Mg Filaments for Fused Deposition Modeling.

Additive manufacturing, in particular the fused deposition method, is a quite new interesting technique used to obtain specific 3D objects by depositing layer after layer of material. Generally, commercial filaments can be used in 3D printing. However, the obtention of functional filaments is not so easy to reach. In this work, we obtain filaments based on poly(lactic acid), PLA, reinforced with different amounts of magnesium, Mg, microparticles, using a two-step extrusion process, in order to study how processing can affect the thermal degradation of the filaments; we additionally study their in vitro degradation, with a complete release of Mg microparticles after 84 days in phosphate buffer saline media. Therefore, considering that we want to obtain a functional filament for further 3D printing, the simpler the processing, the better the result in terms of a scalable approach. In our case, we obtain micro-composites via the double-extrusion process without degrading the materials, with good dispersion of the microparticles into the PLA matrix without any chemical or physical modification of the microparticles.

Investigation of the structural, photoluminescence properties, bioactivity and 5-fluorouracil delivery behavior of Dy3+ and Dy:Eu3+-doped bioactive glasses

Nowadays fluorescent biomaterials gained crucial interest in the biomedical field. Here we report the sol-gel synthesis and characterization of Dy3+ and Dy:Eu3+ co-doped bioactive glass powders. Structural, morphological, and photoluminescence (PL) characteristics of the prepared powders were investigated in detail. Additionally, in vitro hydroxyapatite forming ability and the anticancer drug (5-Fluorouracil) release behavior were investigated with respect to time. The influence of drug loading and delivery on the PL properties was monitored. Results showed that the highest PL intensity was obtained for the 5%Dy:Eu3+ co-doped glass samples. The incorporation of rare-earth ions into the glass network did not cause a significant difference in the structural properties. In vitro conversion experiments, performed in simulated body fluid, indicated that the incorporation of Dy3+ to the glass network enhanced the hydroxyapatite deposition however Dy:Eu3+ co-doping slightly decreased the bioactivity. Drug-loaded bioactive glass powders exhibited sustained drug release behavior to the phosphate buffered saline (PBS) medium. An increase was obtained in the fluorescence intensities for 5-FU-loaded samples followed by a further increase in emissions for the powders released drug to the PBS medium. The findings of the study may be useful for monitoring the degradation of bioactive glasses, conversion to hydroxyapatite as well as drug delivery after implantation.

Design of double functionalized carbon nanotube for amphotericin B and genetic material delivery

In the present work, single wall carbon nanotubes (SWCNT) were successively functionalized with phospholipid DSPE-PEG carboxylic acid, and then, with ethylenediamine (EDA), to obtain double functionalized single wall carbon nanotube (DFSWCNT). Then, DFSWCNT was applied as a carrier for delivering amphotericin B (Amb) and EGFP plasmid. FSWCNT’s concentration obtained via UV–visible analysis was 0.99 mg/mL. The TGA analysis results provided the lost weights of DSPE-PEG-COOH, EDA, Amb and SWCNT impurities. XPS results showed that carbon atoms’ percentage decreased during the functionalization processes from 97.2% (SWCNT) to 76.4% (FSWCNT) and 69.9% (DFSWNCT). Additionally, the oxygen atoms’ percentage increased from 2.3% (SWCNT) to 21% and 22.5% for FSWCNT and DFSWCNT, respectively. New bonds such as C–N and N–C=O appeared in the synthesized nanocarrier. The IG/ID ratio in Raman analysis decreased from 7.15 (SWCNT) to 4.08 (FSWCNT). The amount of Amb released to phosphate buffer saline medium was about 33% at pH = 5.5 and 75% at pH = 7.4 after 48 h. CCK8 results confirmed that the toxicity of functionalized SWCNT had decreased. In a 2:1 ratio of DFSWCNT/EGFP plasmid, the cell viability (87%) and live transfected cells (56%) were at their maximum values. The results indicate that carbon nanotubes have the potential to be applied as drug/gene delivery systems with outstanding properties such as high loading capacity and easy penetration to cell membrane.

In vitro biodegradation, cytotoxicity, and biocompatibility of polylactic acid/napier cellulose nanofiber scaffold composites

This study aimed to evaluate the bioactivities and biocompatibilities of porous polylactic acid (PLA) reinforced with cellulose nanofiber (CNF) scaffolds. The in vitro degradation behaviors of the porous PLA/CNF scaffolds were systematically measured for up to 8 weeks in a phosphate-buffered saline medium at 37 °C. The reinforcement of CNF resisted the biodegradation of the scaffolds. The in vitro cytotoxicity and biocompatibility of the scaffolds were determined using the Beas2B American Type Culture Collection cells. The 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide cytotoxicity and proliferation tests showed that the scaffolds were non-toxic, and epithelial cells grew well on the scaffold after 7 days of culture, whereas the percentage of cell proliferation on the PLA/CNF15 scaffold was the largest, 130 %. A scratch wound-healing assay was performed to evaluate the suitability of the scaffolds for cell migration. The results demonstrated that the scaffolds exhibited good cell migration towards nearly complete wound closure.

Effect of Chitosan and Amphiphilic Polymers on the Photosensitizing and Spectral Properties of Rose Bengal.

The influence of chitosan (CS) and amphiphilic polymers (AP: pluronic F108 and polyvinylpyrrolidone (PVP)) on the photocatalytic activity of rose bengal (RB) in a model reaction of tryptophan photo-oxidation in phosphate-buffered saline (PBS) was studied. It was shown that in the presence of CS, the effective rate constant keff of tryptophan photo-oxidation catalyzed by RB in PBS solution decreases by a factor of two. This is due to the ionic interaction of the RB with the chitosan. Rose bengal in a slightly acidic environment (pH 4.5) passes into a neutral lactone form, which sharply reduces the photosensitizing properties of the dye. It was demonstrated that the introduction of AP into a solution containing RB and CS prevents direct interaction between RB and CS. This is evidenced by the presence of photocatalytic activity of the dye in the RB-AP-CS systems, as well as bathochromic shifts of the main absorption bands of the dye, and an increase in the optical density and luminescence intensity of the RB when AP is introduced into a buffer solution containing RB and chitosan. The presence of RB-CS and RB-AP interaction in aqueous and PBS media is confirmed by the increase in the degree of fluorescence anisotropy (r) of these binary systems. In an aqueous solution, the value of r for the RB-F108-CS system decreases by a factor of 3.5 (compared to the value of r for the RB-CS system), which is associated with the localization of the dye in pluronic micelles. In PBS, the fluorescence anisotropy is practically the same for all systems, which is related to the stability of the dye structure in this medium. The presence of interaction between RB and AP in aqueous solutions was confirmed by the proton NMR method. In addition, the formation of RB-F108 macromolecular complexes, which form associates during solution concentration (in particular, during evaporation), was shown by AFM. Such RB-AP-CS systems may be promising for practical application in the treatment of local foci of infections by aPDT.

Antibacterial Activity and Mechanism of Linalool against Shigella sonnei and Its Application in Lettuce

Shigella sonnei (S. sonnei) infection accounted for approximately 75% of annual outbreaks of shigellosis, with the vast majority of outbreaks due to the consumption of contaminated foods (e.g., fresh vegetables, potato salad, fish, beef, etc.). Thus, we investigated the antibacterial effect and mechanism of linalool on S. sonnei and evaluated the effect of linalool on the sensory quality of lettuce. The minimum inhibitory concentration (MIC) of linalool against S. sonnei ATCC 25931 was 1.5 mg/mL. S. sonnei was treated with linalool at 1× MIC for 30 min and the amount of bacteria was decreased below the detection limit (1 CFU/mL) in phosphate-buffered saline (PBS) and Luria-Bertani (LB) medium. The bacterial content of the lettuce surface was reduced by 4.33 log CFU/cm2 after soaking with linalool at 2× MIC. Treatment with linalool led to increased intracellular reactive oxygen species (ROS) levels, decreased intracellular adenosine-triphosphate (ATP) content, increased membrane lipid oxidation, damaged cell membrane integrity, and hyperpolarized cell membrane potential in S. sonnei. The application of linalool to lettuce had no effect on the color of lettuce compared to the control. The sensory evaluation results showed that linalool had an acceptable effect on the sensory quality of lettuce. These findings indicate that linalool played an antibacterial effect against S. sonnei and had potential as a natural antimicrobial for the inhibition of this foodborne pathogen.

Superparamagnetic Tragacanth Coated Fe3O4@SiO2 Nanoparticles for the Loading and Delivery of Metformin.

A novel superparamagnetic nano-composite of Fe3O4@SiO2 coated by tragacanth gum (TG) as a natural product has been prepared. The obtained SiO2@Fe3O4@TG nanoparticles were characterized by Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy and dynamic light scattering analyzer. The magnetic nano-composite was applied for the loading and delivery of metformin, an oral diabetes medicine. The conditions for the loading of the drug were optimized by a central composite design optimization method. The maximum loading efficiency of the sorbent for metformin was obtained at pH 7 and its maximum in-vitro release was achieved at pH 1.6, using a phosphate-buffered saline medium. The loading capacity of the sorbent was dependent on the initial metformin concentration and exceeded to 19.6 mg/g in a 200 mg/L solution. A study of the adsorption isotherms for the drug indicated the best fitting into the Langmuir and Freundlich isotherms at the low and high metformin concentrations, respectively. The results indicated that the prepared Fe3O4@SiO2@TG adsorbent, as a non-toxic and low-cost sorbent, was quite appropriate for drug delivery applications.