The presence of uncoated gold nanoparticle aggregates may alter the phase of phosphatidylcholine lipid as evidenced by vibrational spectroscopies.

Spherical structures built from uni- and multilamellar lipid bilayers (LUV and MLV) are nowadays considered not just as nanocarriers of various kinds of therapeutics, but also as the vehicles that, when coupled with gold (Au) nanoparticles (NPs), can also serve as a tool for imaging and discriminating healthy and diseased tissues. Since the presence of Au NPs or their aggregates may affect the properties of the drug delivery vehicle, we investigated how the shape and position of Au NP aggregates adsorbed on the surface of MLV affect the arrangement and conformation of lipid molecules. By preparing MLVs constituted from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of uncoated Au NP aggregates found i) both within liposome core and on the surface of the outer lipid bilayer, or ii) adsorbed on the outer lipid bilayer surface only, we demonstrated the maintenance of lipid bilayer integrity by microscopic techniques (cryo-TEM, and AFM). The employment of SERS and FTIR-ATR techniques enabled us not only to elucidate the lipid interaction pattern and their orientation in regards to Au NP aggregates but also unequivocally confirmed the impact of Au NP aggregates on the persistence/breaking of van der Waals interactions between hydrocarbon chains of DPPC.

Label-free SERS for rapid identification of interleukin 6 based on intrinsic SERS fingerprint of antibody­gold nanoparticles conjugate.

A label-free surface-enhanced Raman scattering (SERS) was designed for sensitive detection of interleukin-6 (IL-6). The sensing element composed of anti-IL-6 antibodies adsorbed on the surface of spherical gold nanoparticles (AuNPs) as SERS-active surface. The principle of detection was probing antibody conformational changes using its intrinsic SERS fingerprint after binding to IL-6. Comparison of SERS spectra of antibody before and after binding to IL-6 showed that secondary structure of antibody does not change upon binding to IL-6. Vibrational information from disulfide bonds ν(SS) in antibody structure indicated some changes of geometry around SS bridges as a consequence of the immunocomplex formation. Transmission electron microscopy (TEM) and UV-Vis spectroscopy were used to confirm AuNPs conjugation with antibody as well as IL-6 binding to antibody on the surface of AuNPs. The SERS-based immunoassay showed a wide linear range (2.0-1000 pg mL-1) and a high sensitivity with a limit of detection (LOD) as low as 0.91 pg mL-1 (0.04 pM) without using any extrinsic Raman label. UV-Vis spectroscopy was employed as a conventional method for IL-6 detection based on observation of any change in the position of localized surface plasmon resonance (LSPR) band of AuNPs-antibody conjugates with LOD of 10 ng mL-1.

Recent Progresses in Optical Biosensors for Interleukin 6 Detection.

Interleukin 6 (IL-6) is pleiotropic cytokine with pathological pro-inflammatory effects in various acute, chronic and infectious diseases. It is involved in a variety of biological processes including immune regulation, hematopoiesis, tissue repair, inflammation, oncogenesis, metabolic control, and sleep. Due to its important role as a biomarker of many types of diseases, its detection in small amounts and with high selectivity is of particular importance in medical and biological fields. Laboratory methods including enzyme-linked immunoassays (ELISAs) and chemiluminescent immunoassays (CLIAs) are the most common conventional methods for IL-6 detection. However, these techniques suffer from the complexity of the method, the expensiveness, and the time-consuming process of obtaining the results. In recent years, too many attempts have been conducted to provide simple, rapid, economical, and user-friendly analytical approaches to monitor IL-6. In this regard, biosensors are considered desirable tools for IL-6 detection because of their special features such as high sensitivity, rapid detection time, ease of use, and ease of miniaturization. In this review, current progresses in different types of optical biosensors as the most favorable types of biosensors for the detection of IL-6 are discussed, evaluated, and compared.

Designing ultra-stable linseed oil-in-water Mickering emulsions using whey protein isolate cold-set microgels containing marjoram aqueous extract: Effect of pH and extract on rheological, physical, and chemical properties.

In this study, whey protein isolate (WPI) cold-set microgels containing marjoram (Origanum majorana) aqueous extract (MAE) were prepared at different pHs (4.0, 5.0, and 6.0). After characterization, the microgel dispersion was used to stabilize linseed oil-in-water Mickering emulsions (MEs). The resultant MEs were then characterized in terms of physicochemical and rheological properties under the effect of pH and MAE addition. The morphology, particle size, zeta potential, and interfacial tension of microgels were affected by pH and MAE. XRD patterns showed the amorphous structure. Microgel-stabilized MEs did not reveal any significant sign of instability under gravity during 6 months of storage. All MEs had dominant elastic character. Despite the lowest zeta potential values, MEs prepared at pH 4 showed the highest physical stability against gravity but the lowest centrifugal stability against oiling off, which indicated that both viscous and elastic components are required for MEs stability. This sample had the highest apparent viscosity and the strongest viscoelastic properties. Rheological data were best fitted with Herschel-Bulkley and Power Law models. An increase in pH and presence of MAE improved the oxidative stability of MEs. The results of this study showed that WPI microgels are appropriate candidate for long-term stabilization of linseed oil-in-water MEs. The presence of MAE is useful in designing special emulsions in which the aqueous phase is partially replaced by the aqueous extract of medicinal plants.

Development and characterization of a novel biodegradable and antioxidant film based on marine seaweed sulfated polysaccharide.

This research aims to produce an antioxidant and biodegradable polysaccharide film by using macroalgae agar and sulfated polysaccharide. Agar and sulfated polysaccharide (fucoidan) were extracted from Gracilaria corticata and Sargassum angustifolium macroalgae. Five treatments were conducted: (A) agar film (1%, W:V), (C) chitosan film (1%, W:V + 1% acetic acid), (AC) agar:chitosan composite (50:50, V:V), (ACF) AC film with fucoidan (0.5%, W:V), and (ACFA) ACF film with citric acid (30% of the dry weight of film) as a cross-linking agent. Then, 0.75% (V:V) of glycerol was added to all films. The physical, mechanical, antioxidant, color variations, microstructure (SEM), and Fourier transform infrared (FT-IR) spectroscopy were investigated. Based on the results, modifying the agar film with chitosan improved the mechanical strength, humidity, and solubility in the AC composite film (p < .05). Further, adding sulfated polysaccharide and citric acid cross-linking agent to the agar-chitosan composite led to a significant decrease in solubility, humidity, and permeability to water vapor in ACFA films (p < .05), indicating strong cross-linking and reduction in film pores based on the SEM pictures and FTIR results. However, the physical and mechanical properties of the agar-based film obtained from Gracilaria algae can be improved by adding chitosan and citric acid cross-linking agent, and the addition of fucoidan obtained from Sargassum algae has improved its antioxidant properties. This biodegradable film can be a good candidate for preserving perishable products.

Development and characterization of antimicrobial alginate hydrogel beads filled with cinnamon essential oil nanoemulsion.

The aim of the present study was to investigate the characteristics of alginate beads filled with cinnamon essential oil nanoemulsions (CEONs). The influence of the alginate and CaCl2 concentrations on their physical, antimicrobial and antioxidant properties was studied. The droplet size of CEON was 146.20 ± 39.28 nm and the zeta potential was -33.8 ± 0.72 mV demonstrating proper nanoemulsions stability. Decreasing the alginate and CaCl2 concentrations resulted in higher EOs release due to the increased pore size of the alginate beads. The scavenging activity of DPPH of beads was found to be dependent on the alginate and calcium ion concentrations which affected the pore size of the fabricated beads. The FT-IR results declared the new bands in the spectra of filled hydrogel beads, which verified the encapsulation of EOs in the beads. The surface morphology of beads was studied using SEM images which showed the spherical shape and porous structure of alginate beads. In addition, the alginate beads filled with CEO nanoemulsion demonstrated strong antibacterial activity.

Microencapsulation of Lacticaseibacillus rhamnosus GG and L. plantarum 299 V by reverse spherification: a promising method to improve the survival of probiotics.

This research reports the first application of the reverse spherification (RVS) method for encapsulation of two probiotics (Lacticaseibacillus rhamnosus GG and L. plantarum 299 V) compared to the basic spherification (BS). These probiotics were encapsulated in different solutions encompassing various contents of alginate, gelatin, and gellan gum. The RVS bead diameters was about 1.5 times bigger and hardness was 70%-80% lower than BS samples. As determined by Raman spectral mapping, the RVS beads had two calcium alginate walls but the BS beads had only one. The inner wall of the RVS beads was more than three times thicker than outer wall. The encapsulation yields of gelatin/gellan gum and gelatin beads prepared by both methods were >1.5% alginate beads. All the RVS-prepared beads were resistant to stomach acid and showed no significant reduction in the intestine. Furthermore, the incorporation of gelatin and gellan gum into alginate led to higher cell protection. For 1.5% alginate beads, <67% survival was achieved after acid exposure but in others, >77% survival was observed; RVS beads were about 1 log above than BS ones. The proposed novel microencapsulation method efficiently increased the viability of probiotic bacteria compared to the conventional approaches.

Production and characterization of sage seed gum bioactive film containing Zataria multiflora essential oil nanoemulsion.

A bioactive film with two concentrations of sage seed gum (SSG) (1 % and 1.5 %) incorporating 2 % and 4 % Zataria multiflora essential oil (ZMEO) nanoemulsion was developed. Microbiological evaluation, including disc diffusion and time-kill tests, as well as mechanical and chemical characteristics namely film thickness, water-solubility, water vapor permeability, tensile strength and elongation at break, scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR) analysis, antioxidant activity, and color analysis, were examined. Results showed that the antimicrobial properties of SSG films incorporating ZMEO nanoemulsion increased significantly (P < 0.05) by the multiplication of essential oil concentration. The films with 1 % SSG-4 % ZMEO showed acceptable antioxidant properties (∼65 %), and improved physical properties (508 % thickness increase, 56.63 % water solubility decrease, and 36.85 % water vapor permeability decrease), whereas tensile strength decreased only 29.8 %, and elongation increased 115 %. According to the results, SSG-ZMEO film may have positive potential impacts on increasing the shelf-life of foodstuffs.

Effects of natural antioxidants and high-energy fabrication methods on physical properties and oxidative stability of flaxseed oil-in-water nanoemulsions.

The effects of high-energy fabrication methods, namely high-pressure homogenization (HPH) and ultrasonication (US), on physicochemical properties of flaxseed oil-in-water nanoemulsions (FNEs) containing clove essential oil (CEO) and/or pomegranate peel extract (PPE) were studied during storage at 4 and 25 °C. Nanoemulsions with relatively similar average droplet size were prepared by HPH and/or US. An increase in droplet size was observed over time. Lower storage temperature and fabrication by US increased Ostwald ripening rate. Higher storage temperature and fabrication by US decreased the centrifugal stability of nanoemulsions. CEO revealed better antioxidant properties than PPE. The oxidative stability was evaluated by determining secondary oxidation products, and fatty acids profile. The absence of antioxidant, fabrication by US, and higher storage temperature decreased the oxidative stability of nanoemulsions. The results of this study might be helpful in controlling the oxidation of FNEs during long-term storage and in designing functional foods and beverages.

Antifungal activity of protective cultures against the yogurt drink-specific spoilage yeasts.

Fungal agents emerged as post-pasteurization contamination are responsible for the spoilage in yogurt drink. In this work, the antifungal effects of some lactic acid bacteria (LAB) on the spoilage yeasts isolated from yogurt drink (Doogh) were evaluated. First, the microbial growth in the yogurt drink samples during the storage time was investigated, and the isolated microorganisms were identified using biochemical methods and sequencing of the specific amplicons. Yeasts (3-7 log CFU ml-1 ) were found to be the most abundant microorganisms (specific spoilage organisms) in several samples. Using the amplification technique of rDNA by ITS1 and ITS4 primers, the dominant yeasts were identified as Pichia kudriavzevii, Kluyveromyces marxianus, and Candida parapsilosis. Then, the antimicrobial activity of 37 strains of LAB against the isolated yeasts was studied using broth microdilution. Eventually, the strains of Lacticplantibacillus plantarum (245, 24, P6, and P7), Lactiplantibacillus pentosus (20), and Levilactobacillus brevis (30) exhibited significant antifungal activity. In the most effective impacts, lag times of C. parapsilosis, K. marxianus, and P. kudriavzevii were increased by almost 12-19 h, 12-19 h, and 2-6 h, respectively, while the area under the growth curve for these yeasts was reduced to lower than 40%, near 16%, and approximately 67%, in the order given. Overall, these bacteria showed high potential as the substituents for chemical preservatives in yogurt drinks. PRACTICAL APPLICATION: Spoilage yeasts were isolated from yogurt drink and identified by molecular method. Isolated yeasts belonged to Pichia, Kluyveromyces, and Candida genera. Inhibitory effects of 37 strains were evaluated against the spoilage yeasts. Cell-free supernatant was used against the isolated fungi in microdilution method. Several LAB strains showed a significant antimicrobial activity.

Recent Advances in Electrochemical Aptasensors for Detection of Biomarkers.

The early diagnosis of diseases is of great importance for the effective treatment of patients. Biomarkers are one of the most promising medical approaches in the diagnosis of diseases and their progress and facilitate reaching this goal. Among the many methods developed in the detection of biomarkers, aptamer-based biosensors (aptasensors) have shown great promise. Aptamers are promising diagnostic molecules with high sensitivity and selectivity, low-cost synthesis, easy modification, low toxicity, and high stability. Electrochemical aptasensors with high sensitivity and accuracy have attracted considerable attention in the field of biomarker detection. In this review, we will summarize recent advances in biomarker detection using electrochemical aptasensors. The principles of detection, sensitivity, selectivity, and other important factors in aptasensor performance are investigated. Finally, advantages and challenges of the developed aptasensors are discussed.

Wheat Germ Fermentation with Saccharomyces cerevisiae and Lactobacillus plantarum: Process Optimization for Enhanced Composition and Antioxidant Properties In Vitro.

Wheat germ, a by-product of the flour milling industry, is currently commercialized mainly for animal feed applications. This study aims to explore and optimize the process of wheat germ fermentation to achieve products with enhanced nutritional composition and biological properties and further characterize the fermented products generated using these optimum conditions. The type of microorganism (Saccharomyces cerevisiae 5022 (yeast) and Lactobacillus plantarum strain 299v (bacteria)), pH (4.5, 6, and 7.5) and fermentation time (24, 48, and 72 h) were optimized using response surface methodology (RSM) aiming to achieve fermented products with high total phenol content (TPC), dimethoxy benzoquinone (DMBQ) and antioxidant activities. Optimum fermentation conditions were achieved using L. plantarum, pH 6, 48 h, generating extracts containing TPC (3.33 mg gallic acid equivalents/g), DMBQ (0.56 mg DMBQ/g), and DPPH radical scavenging (86.49%). These optimally fermented products had higher peptide concentrations (607 µg/mL), gamma-aminobutyric acid (GABA) (19,983.88 mg/kg) contents compared to non-fermented or yeast-fermented products. These findings highlight the influence of fermentation conditions of wheat germ and the promising industrial application of wheat germ fermentation for developing food products with enhanced biological properties promising for their commercialization as functional foods.

Aptamer-Based Lateral Flow Assays: Current Trends in Clinical Diagnostic Rapid Tests.

The lateral flow assay (LFA) is an extensively used paper-based platform for the rapid and on-site detection of different analytes. The method is user-friendly with no need for sophisticated operation and only includes adding sample. Generally, antibodies are employed as the biorecognition elements in the LFA. However, antibodies possess several disadvantages including poor stability, high batch-to-batch variation, long development time, high price and need for ethical approval and cold chain. Because of these limitations, aptamers screened by an in vitro process can be a good alternative to antibodies as biorecognition molecules in the LFA. In recent years, aptamer-based LFAs have been investigated for the detection of different analytes in point-of-care diagnostics. In this review, we summarize the applications of aptamer technology in LFAs in clinical diagnostic rapid tests for the detection of biomarkers, microbial analytes, hormones and antibiotics. Performance, advantages and drawbacks of the developed assays are also discussed.

Development of a natamycin-based non-migratory antimicrobial active packaging for extending shelf-life of yogurt drink (Doogh).

A natamycin-based non-migratory antimicrobial packaging for extending shelf-life of yogurt drink (Doogh) was developed. Firstly, the surface of low-density polyethylene film (LDPE) was modified with acrylic acid at different times of UV exposure (0-10 min) to produce carboxylic functional groups. Then, natamycin was applied to the UV-treated films to bind covalently with the pendent functional groups. The maximum grafting efficiency (81.96%) was obtained for the 6 min treated film. Moreover, surface properties of films were evaluated by Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Antifungal activity of different treatments of natamycin grafted film was evaluated against two common spoilage yeasts of Doogh including Rhodotorula mucilaginosa and Candida parapsilosis. Results showed that 6 min treated film provides maximum anti-yeast activity and can be applied to control fungal growth in Doogh. Natamycin-grafted film postponed the yeast spoilage in Doogh and prolonged its shelf-life to 23 days.

Recent developments in non-enzymatic (bio)sensors for detection of pesticide residues: Focusing on antibody, aptamer and molecularly imprinted polymer.

The utilization of pesticides has been increased in recent years due to population growth and increasing urbanization. The constant use of pesticides has resulted in contamination of the environment and agricultural products with serious human health concerns associated with their use. Therefore, detection and quantification of pesticides by sensitive and selective methods is highly required in food safety management. Traditional detection methods cannot realize highly sensitive, selective and on-site detection, which limits their application. (Bio)sensors and (bio)assays are emerging tools with unique properties such as rapid, sensitive, efficient and portable detection. Among them, enzyme-based biosensors have been widely developed and some have even been commercialized. However, they suffer from some limitations such as instability and low reproducibility that originate from the nature of enzyme. Non-enzymatic (bio)sensors overcome the current limitations of enzyme-based detection methods and provide great potential for efficient, highly sensitive and low-cost detection assays using smart and miniaturized devices. In this study, we provide an overview of recent advances and new trends in optical and electrochemical non-enzymatic (bio)sensors for the detection of pesticides by focusing on antibody, aptamer and molecularly imprinted polymer (MIP) as recognition elements. Performance, advantages and drawbacks of the developed (bio)sensors are discussed well. The main advantage these recognition elements is their stability over an extended period of time compared to the enzymes. Furthermore, the combination of nanomaterials in these (bio)sensors can significantly improve their performance.

An Overview of Optical and Electrochemical Sensors and Biosensors for Analysis of Antioxidants in Food during the Last 5 Years.

Antioxidants are a group of healthy substances which are useful to human health because of their antihistaminic, anticancer, anti-inflammatory activity and inhibitory effect on the formation and the actions of reactive oxygen species. Generally, they are phenolic complexes present in plant-derived foods. Due to the valuable nutritional role of these mixtures, analysis and determining their amount in food is of particular importance. In recent years, many attempts have been made to supply uncomplicated, rapid, economical and user-friendly analytical approaches for the on-site detection and antioxidant capacity (AOC) determination of food antioxidants. In this regards, sensors and biosensors are regarded as favorable tools for antioxidant analysis because of their special features like high sensitivity, rapid detection time, ease of use, and ease of miniaturization. In this review, current five-year progresses in different types of optical and electrochemical sensors/biosensors for the analysis of antioxidants in foods are discussed and evaluated well. Moreover, advantages, limitations, and the potential for practical applications of each type of sensors/biosensors have been discussed. This review aims to prove how sensors/biosensors represent reliable alternatives to conventional methods for antioxidant analysis.

Advances in Colorimetric Strategies for Mycotoxins Detection: Toward Rapid Industrial Monitoring.

Mycotoxins contamination is a global public health concern. Therefore, highly sensitive and selective techniques are needed for their on-site monitoring. Several approaches are conceivable for mycotoxins analysis, among which colorimetric methods are the most attractive for commercialization purposes thanks to their visual read-out, easy operation, cost-effectiveness, and rapid response. This review covers the latest achievements in the last five years for the development of colorimetric methods specific to mycotoxins analysis, with a particular emphasis on their potential for large-scale applications in food industries. Gathering all types of (bio)receptors, main colorimetric methods are critically discussed, including enzyme-linked assays, lateral flow-assays, microfluidic devices, and homogenous in-solution strategies. This special focus on colorimetry as a versatile transduction method for mycotoxins analysis is comprehensively reviewed for the first time.

Production of GABA-enriched idli with ACE inhibitory and antioxidant properties using Aspergillus oryzae: the antihypertensive effects in spontaneously hypertensive rats.

The present study aimed to develop a fermented food (idli) with enhanced γ-aminobutyric acid (GABA) and angiotensin I-converting enzyme (ACE) inhibitory properties using a GABA-producing fungus. Aspergillus oryzae NSK fermented idli batter and GABA was maximized (451.7 mg kg-1) in 120 h. The ACE inhibitory, 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging and nitric oxide radical scavenging activities increased to 41.8%, 1.9 and 0.6 µmol trolox equivalent antioxidant capacity (TEAC) per gram in 120 h, respectively. In contrast, phytic acid and trypsin inhibitor activities decreased to 3.01 g kg-1 and 30.8 mg kg-1, respectively. The systolic blood pressure of spontaneously hypertensive rats in the fermented idli diet group was lower than those fed a plain idli diet. Lipid peroxidation in the plain idli diet group was significantly higher, whereas superoxide dismutase and glutathione reductase activities were significantly lower. The expression of genes ET-1, HSP70, NF-κB and iNOS in the aorta of SHRs that received GABA-containing diets was down-regulated between 2.2 and 3.8 fold. The production of GABA-enriched foods can be a promising approach to lower the blood pressure of spontaneously hypertensive rats.

Optical and Electrochemical Sensors and Biosensors for the Detection of Quinolones.

One major concern associated with food safety is related to residual effects of antibiotics that are widely used to treat animals and result in antimicrobial resistance. Among different groups of antibiotic, the use of quinolones in livestock is of major concern due to the significance of these antimicrobial drugs for the treatment of a range of infectious diseases in humans. Therefore, it is desirable to develop reliable methods for the rapid, sensitive, and on-site detection of quinolone residue levels in animal-derived foods to ensure food safety. Sensors and biosensors are promising future platforms for rapid and on-site monitoring of antibiotic residues. In this review, we focus on recent advancements and modern approaches in quinolone sensors and biosensors.

Development of a new format of competitive immunochromatographic assay using secondary antibody-europium nanoparticle conjugates for ultrasensitive and quantitative determination of ochratoxin A.

In this study, to enhance the sensitivity of conventional immunochromatographic assay (ICA) two strategies including using a high sensitive label and changing the assay format, were simultaneously applied to develop an ultrasensitive format of ICA. In new format, primary monoclonal antibody against ochratoxin A (OTA) was used without any labeling, and a secondary polycolonal antibody was labeled with europium fluorescent nanoparticles (EuNPs). Detection was performed in a single step by inserting the test strip into a microtube containing all reagents. The results were obtained within 12 min and read by a portable fluorescent strip reader. Salient features of the new format of ICA compared with conventional format include: (1) A 100-fold decrease in limit of detection (LOD) due to application of two amplification strategy; (2) Reduction in expensive monoclonal antibody consumption. The established method was evaluated for the quantitative determination of OTA with LOD as low as 0.4 pg mL-1.