Yeast cell vacuum infusion into fungal pellets as a novel cell encapsulation methodology.

Immobilized yeast cells are used industrially in winemaking processes such as sparkling wine and Sherry wine production. Here, a novel approach has been explored for the infusion and immobilization of yeast cells into filamentous fungal pellets, which serve as a porous natural material. This was accomplished through vacuum application to force the yeast cells towards the core of the fungal pellets followed by culture in YPD medium to promote their growth from the interior. This method represents an improved variation of a previous approach for the assembly of "yeast biocapsules," which entailed the co-culture of both fungal and yeast cells in the same medium. A comparison was made between both techniques in terms of biocapsule productivity, cell retention capacity, and cell biological activity through an alcoholic fermentation of a grape must. The results indicated a substantial increase in biocapsule productivity (37.40-fold), higher cell retention within the biocapsules (threefold), and reduction in cell leakage during fermentation (twofold). Although the majority of the chemical and sensory variables measured in the produced wine did not exhibit notable differences from those produced utilizing suspended yeast cells (conventional method), some differences (such as herbaceous and toasted smells, acidity, bitterness, and persistence) were perceived and wines positively evaluated by the sensory panel. As the immobilized cells remain functional and the encapsulation technique can be expanded to other microorganisms, it creates potential for additional industrial uses like biofuel, health applications, microbe encapsulation and delivery, bioremediation, and pharmacy. KEY POINTS: • New approach improves biocapsule productivity and cell retention. • Immobilized yeast remains functional in fermentation. • Wine made with immobilized yeast had positive sensory differences.

Flor yeast immobilization in microbial biocapsules for Sherry wine production: microvinification approach.

Sherry wine is a pale-yellowish dry wine produced in Southern-Spain which features are mainly due to biological aging when the metabolism of biofilm-forming yeasts (flor yeasts) consumes ethanol (and other non-fermentable carbon sources) from a previous alcoholic fermentation, and produces volatile compounds such as acetaldehyde. To start aging and maintain the wine stability, a high alcohol content is required, which is achieved by the previous fermentation or by adding ethanol (fortification). Here, an alternative method is proposed which aims to produce a more economic, distinctive Sherry wine without fortification. For this, a flor yeast has been pre-acclimatized to glycerol consumption against ethanol, and later confined in a fungal-based immobilization system known as "microbial biocapsules", to facilitate its inoculum. Once aged, the wines produced using biocapsules and free yeasts (the conventional method) exhibited chemical differences in terms of acidity and volatile concentrations. These differences were evaluated positively by a sensory panel. Pre-acclimatization of flor yeasts to glycerol consumption was not successful but when cells were immobilized in fungal pellets, ethanol consumption was lower. We believe that immobilization of flor yeasts in microbial biocapsules is an economic technique that can be used to produce high quality differentiated Sherry wines.

Lactic Acid Bacteria Simultaneously Encapsulate Diverse Bioactive Compounds from a Fruit Extract and Enhance Thermal Stability.

This study develops an innovative cell-based carrier to simultaneously encapsulate multiple phytochemicals from a complex plant source. Muscadine grapes (MG) juice prepared from fresh fruit was used as a model juice. After incubation with inactivated bacterial cells, 66.97% of the total anthocyanins, and 72.67% of the total antioxidant compounds were encapsulated in the cells from MG juice. Confocal images illustrated a uniform localization of the encapsulated material in the cells. The spectral emission scans indicated the presence of a diverse class of phenolic compounds, which was characterized using high-performance liquid chromatography (HPLC). Using HPLC, diverse phytochemical compound classes were analyzed, including flavanols, phenolic acid, hydroxycinnamic acid, flavonols, and polymeric polyphenols. The analysis validated that the cell carrier could encapsulate a complex profile of bioactive compounds from fruit juice, and the encapsulated content and efficiencies varied by the chemical class and compound. In addition, after the heat treatment at 90 °C for 60 min, >87% total antioxidant capacity and 90% anthocyanin content were recovered from the encapsulated MG. In summary, these results highlight the significant potential of a selected bacterial strain for simultaneous encapsulation of diverse phenolic compounds from fruit juice and improving their process stability.

Synergistic Antimicrobial Activity by Light or Thermal Treatment and Lauric Arginate: Membrane Damage and Oxidative Stress.

The need for more effective antimicrobials is critical for the food industry to improve food safety and reduce spoilage of minimally processed foods. The present study was initiated to develop an efficient and novel antimicrobial approach which combines physical treatments (UV-A or mild heat) and generally recognized as safe lauroyl arginate ethyl (LAE) to inactivate surrogate strains, including Escherichia coli and Listeria innocua Synergistic inactivation of bacteria resulted in an ∼6-log reduction of target bacteria, while individual treatments resulted in <1.5-log inactivation under the same set of conditions. In addition, the synergistic mechanism between LAE and UV-A/mild heat was evaluated by supplementing with a variety of antioxidants for suppressing oxidative stress and measurement of cell membrane damage by nucleic acid release. These results demonstrate that the synergistic antimicrobial activity of LAE and mild physical stresses was suppressed by supplementation with antioxidants. The research also compared LAE with another membrane-targeting lipopeptide antimicrobial agent, polymyxin B, to understand the uniqueness of LAE-induced synergy. Briefly, differences in modes of action between LAE and polymyxin B were characterized by comparing the MIC, damage to liposomes, and oxidative stress generation. These differences in the mode of action between LAE and polymyxin B suggested that both compounds target cell membrane but significantly differ in mechanisms, including membrane disruption and oxidative stress generation. Overall, this study illustrates synergistic antimicrobial activity of LAE with light or mild heat and indicates a novel oxidative stress pathway that enhances the activity of LAE beyond membrane damage.IMPORTANCE This study highlights an effective antimicrobial processing approach using a novel combination of lauroyl arginate ethyl (LAE) and two different physical treatments, light (UV-A) and mild heat. Both combinations demonstrated synergistic inactivation against a model Gram-negative bacterium or a Gram-positive bacterium or both by a >5-log reduction. Further mechanistic study revealed that oxidative stress is responsible for synergistic inactivation between LAE and UV-A, while both membrane damage and oxidative stress are responsible for the synergistic combination between LAE and mild heat. The mode of action of LAE was further compared to that of polymyxin B and analyzed using artificial membrane model systems and the addition of antioxidants. The proposed combination of LAE and common physical treatments may improve food preservation, food safety, and current sanitation processes for the food industry and the inactivation of pathogenic strains in biomedical environments.

Evidence of water-in-ionic liquid microemulsion formation by nonionic surfactant Brij-35.

Brij-35, a common and popular nonionic surfactant, is shown to form water-in-ionic liquid (w/IL) microemulsions with IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) as the bulk phase. The presence of w/[bmim][PF6] microemulsions is hinted by the significantly increased solubility of water in Brij-35 solution of [bmim][PF6]. The formation of w/[bmim][PF6] microemulsions by Brij-35 is confirmed using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements. Brij-35 forms reverse micelle-type aggregates within [bmim][PF6] in the absence of added-water. These reverse micelles become w/[bmim][PF6] microemulsions as the water is added to the system. As the water loading (w0) is increased, the average diameter of the aggregates increases. Fourier transform infrared (FTIR) absorbance data reveal the presence of both "bound" and "free" water within the system. The "bound" water is associated with the water pools of the w/[bmim][PF6] microemulsions. Excited-state proton transfer (ESPT) involving probe pyranine shows deprotonation of pyranine within the water pools of the w/[bmim][PF6] microemulsions.

Self-aggregation of sodium dodecyl sulfate within (choline chloride + urea) deep eutectic solvent.

Deep eutectic solvents (DESs) have shown tremendous promise as green solvents with low toxicity and cost. Understanding molecular aggregation processes within DESs will not only enhance the application potential of these solvents but also help alleviate some of the limitations associated with them. Among DESs, those comprising choline chloride and appropriate hydrogen-bond donors are inexpensive and easy to prepare. On the basis of fluorescence probe, electrical conductivity, and surface tension experiments, we present the first clear lines of evidence for self-aggregation of an anionic surfactant within a DES containing a small fraction of water. Namely, well-defined assemblies of sodium dodecyl sulfate (SDS) apparently form in the archetype DES Reline comprising a 1:2 molar mixture of choline chloride and urea. Significant enhancement in the solubility of organic solvents that are otherwise not miscible in choline chloride-based DESs is achieved within Reline in the presence of SDS. The remarkably improved solubility of cyclohexane within SDS-added Reline is attributed to the presence of spontaneously formed cyclohexane-in-Reline microemulsions by SDS under ambient conditions. Surface tension, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), density, and dynamic viscosity measurements along with responses from the fluorescence dipolarity and microfluidity probes of pyrene and 1,3-bis(1-pyrenyl)propane are employed to characterize these aggregates. Such water-free oil-in-DES microemulsions are appropriately sized to be considered as a new type of nanoreactor.

Aggregation of a model porphyrin within poly(ethylene glycol) (PEG): effect of water, PEG molecular weight, ionic liquids, salts, and temperature.

Understanding molecular aggregation within environmentally-benign media is of utmost importance. Aggregation of a common porphyrin, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP), dissolved in media composed of poly(ethylene glycols) (PEGs) up to an average molecular weight (MW) of 8000 as major components, is investigated. J-aggregates of TSPP are well-manifested via the bathochromically-shifted UV-vis absorbance band of TSPP. As media, 10 wt% water-added PEGs at pH 1 show excellent efficiency for TSPP J-aggregation. The J-aggregation efficiency increases as the PEG MW is increased and it is found to be the maximum for the medium constituted of PEG3000. Once formed, some of the J-aggregates decay back to the diprotonated form via pseudo-first order kinetics. Addition of salts NaCl and NaBF4 and ionic liquids [bmim][PF6], [bmim][Tf2N], [bmim][BF4], and [bmim][OTf] [bmim = 1-butyl-3-methylimidazolium, PF6 = hexafluorophosphate, Tf2N = bis(trifluoromethylsulfonyl)imide, BF4 = tetrafluoroborate, and OTf = trifluoromethanesulfonate], respectively, to TSPP dissolved in 10 wt% water added PEGs at pH 1 results in increased J-aggregation efficiency. Ionic liquids are found to protect porphyrin J-aggregates from decaying to their diprotonated form. Increasing temperature from ambient to 90 °C results in decreased J-aggregation efficiency of TSPP in the presence of salts NaCl and NaBF4, respectively; concentration of J-aggregates does not change much with temperature when an ionic liquid as an additive is present in the medium. The polymer chain length and electrostatic interactions appear to play a major role in porphyrin J-aggregation efficiency and kinetics within water-added acidic mixtures of PEG.

How polar are choline chloride-based deep eutectic solvents?

Developing and characterizing green solvents with low toxicity and cost is one of the most important issues in chemistry. Deep Eutectic Solvents (DESs), in this regard, have shown tremendous promise. Compared to popular organic solvents, DESs possess negligible VOCs and are non-flammable. Compared to ionic liquids, which share many characteristics but are ionic compounds and not ionic mixtures, DESs are cheaper to make, much less toxic and mostly biodegradable. An estimate of the polarity associated with DESs is essential if they are to be used as green alternatives to common organic solvents in industries and academia. As no one physical parameter can satisfactorily represent solute-solvent interactions within a medium, polarity of DESs is assessed through solvatochromic optical spectroscopic responses of several UV-vis absorbance and molecular fluorescence probes. Information on the local microenvironment (i.e., the cybotactic region) that surrounds several solvatochromic probes [betaine dye, pyrene, pyrene-1-carboxaldehyde, 1-anilino-8-naphthalene sulfonate (ANS), p-toluidinyl-6-naphthalene sulfonate (TNS), 6-propionyl-2-(dimethylaminonaphthalene) (PRODAN), coumarin-153, and Nile Red] for four common and popular DESs formed from choline chloride combined with 1,2-ethanediol, glycerol, urea, and malonic acid, respectively, in 1 : 2 molar ratios termed ethaline, glyceline, reline, and maline is obtained and used to assess the effective polarity afforded by each of these DESs. The four DESs as indicated by these probe responses are found to be fairly dipolar in nature. Absorbance probe betaine dye and fluorescence probes ANS, TNS, PRODAN, coumarin-153, and Nile Red, whose solvatochromic responses are based on photoinduced charge-transfer, imply ethaline and glyceline, DESs formed using alcohol-based H-bond donors, to be relatively more dipolar in nature as compared to reline and maline. The pyrene polarity scale, which is based on polarity-induced changes in vibronic bands, indicates reline, the DES composed of urea as the hydrogen bond donor, to be significantly more dipolar than the other three DESs. Response of pyrene-1-carboxaldehyde, a polarity probe based on inversion of n-π* and π-π* states, hints at maline to be the most dipolar of the four DESs. The molecular structure of the H-bond donor in a DES clearly controls the dipolarity afforded by the DES. H-bonding and other specific solute-solvent interactions are found to play an important role in solvatochromic probe behavior for the four DESs. The cybotactic region of a probe dissolved in a DES affords information on the polarity of the DES towards solutes of similar nature and functionality.

Investigating Milk Fat Globule Structure, Size, and Functionality after Thermal Processing and Homogenization of Human Milk.

Human milk provides bioactive compounds such as milk fat globules (MFGs), which promote brain development, modulate the immune system, and hold antimicrobial properties. To ensure microbiological safety, donor milk banks apply heat treatments. This study compares the effects of heat treatments and homogenization on MFG's physicochemical properties, bioactivity, and bioavailability. Vat pasteurization (Vat-PT), retort (RTR), and ultra-high temperature (UHT) were performed with or without homogenization. UHT, RTR, and homogenization increased the colloidal dispersion of globules, as indicated by increased zeta potential. The RTR treatment completely inactivated xanthine oxidase activity (a marker of MFG bioactivity), whereas UHT reduced its activity by 93%. Interestingly, Vat-PT resulted in less damage, with 28% activity retention. Sialic acid, an important compound for brain health, was unaffected by processing. Importantly, homogenization increased the in vitro lipolysis of MFG, suggesting that this treatment could increase the digestibility of MFG. In terms of color, homogenization led to higher L* values, indicating increased whiteness due to finer dispersion of the fat and casein micelles (and thus greater light scattering), whereas UHT and RTR increased b* values associated with Maillard reactions. This study highlights the nuanced effects of processing conditions on MFG properties, emphasizing the retention of native characteristics in Vat-PT-treated human milk.

Excimer formation of 6-(1-pyrenyl)hexyl-11(1-pyrenyl)undecanoate within an ionic liquid and cosolvent-modified ionic liquid mixture.

The ring closing metathesis within an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]), a 'green' solvent tetraethylene glycol (TEG), and their equimolar mixture is investigated through the intramolecular excimer formation of 6-(1-pyrenyl)hexyl-11-(1-pyrenyl)undecanoate [1]. The excimer formation efficiency correlates directly with the inverse of the bulk viscosity of the systems. A simplistic double exponential decay model based on Birk's scheme is enough to fit the excited state intensity decay of 1 in these liquids. This behavior is in stark contrast to that reported in organic solvents and in scCO(2), where three exponentials are required to fit the fluorescence decay. The activation energies of the excimer formation (E(a)), viscous flow (E(a,η(bulk))), and microviscosity (E(a,η(µ))) were estimated from the temperature dependence. E(a) and E(a,η(µ)) are significantly higher for the equimolar mixture as compared to that for [bmim][PF(6)] or TEG, whereas E(a,η(bulk)) is close to the average. This highlights the important outcome that the cyclization dynamics scales with the microviscosity rather than the bulk viscosity of the systems investigated.

Apple-derived 3D scaffold for improving gastrointestinal viability and in-situ growth of probiotics.

This study develops a novel low-cost microbial delivery system by transforming common food materials such as apple tissue into a 3D scaffold. Apple tissue scaffold was constructed by decellularization of intact tissue using a minimal amount of sodium dodecyl sulfate (0.5 % w/v). Vacuum-assisted infusion of model probiotic Lactobacillus cells led to a high encapsulation yield of probiotic cells (1010 CFU/g of scaffold) in 3D scaffolds on a wet basis. The bio-polymer coated 3D scaffolds with infused cells significantly enhanced the survivability of infused probiotic cells during simulated gastric and intestinal digestions. In addition, imaging and plate counting results validate the growth of the infused cells in the 3D scaffold after 1-2 days of fermentation in MRS media, while cells without infusion in the scaffold had limited attachment with the intact apple tissue. Overall, these results highlight the potential of the apple tissue-derived 3D scaffold to deliver probiotic cells and include the biochemical compositions to support the growth of delivered microbial cells in the colon.

Image-based assessment and machine learning-enabled prediction of printability of polysaccharides-based food ink for 3D printing.

Despite the growing demand and interest in 3D printing for food manufacturing, predicting printability of food-grade materials based on biopolymer composition and rheological properties is a significant challenge. This study developed two image-based printability assessment metrics: printed filaments' width and roughness and used these metrics to evaluate the printability of hydrogel-based food inks using response surface methodology (RSM) with regression analysis and machine learning. Rheological and compositional properties of food grade inks formulated using low-methoxyl pectin (LMP) and cellulose nanocrystals (CNC) with different ionic crosslinking densities were used as predictors of printability. RSM and linear regression showed good predictability of rheological properties based on formulation parameters but could not predict the printability metrics. For a machine learning based prediction model, the printability metrics were binarized with pre-specified thresholds and random forest classifiers were trained to predict the filament width and roughness labels, as well as the overall printability of the inks using formulation and rheological parameters. Without including formulation parameters, the models trained on rheological measurements alone were able to achieve high prediction accuracy: 82% for the width and roughness labels and 88% for the overall printability label, demonstrating the potential to predict printability of the polysaccharide inks developed in this study and to possibly generalize the models to food inks with different compositions.

Engineering cell-based microstructures to study the effect of structural complexity on in vitro bioaccessibility of a lipophilic bioactive compound.

A fundamental understanding of the influence of food microstructures on the bioaccessibility of micronutrients is vital for the design of functionally efficient foods. This study investigated the effect of microstructural features of model foods on the bioaccessibility of a bioactive compound - curcumin, using a unique bottom-up approach. In this approach, individual yeast cells with infused curcumin were coated with oppositely charged polyelectrolytes: first in poly(diallyl-dimethylammonium chloride), then in dextran sulfate or alginate, and assembled electrostatically to generate two types of cell clusters. These cell clusters were embedded in an alginate film to form a tissue-like structure. The influence of cell clustering and extracellular matrix on the release of encapsulated curcumin from cell-based microcarriers during simulated digestion was evaluated. Cell clusters that maintained their integrity during in vitro simulated digestion retained up to twice as much curcumin upon addition of the simulated intestinal fluid (SIF) compared to single cells during the first hour of intestinal digestion. Despite significant differences in the release profile, no spatial heterogeneity of curcumin release across a cell cluster was observed with the imaging measurements. Embedding single cells or cell clusters in calcium-crosslinked alginate films resulted in another 20-30% increase in curcumin retention and a prolonged barrier effect for more than 2 hours compared to microstructures without the films. This bottom-up approach of engineering cell-based tissue-like structures proves to be an effective method for investigating the contributions of microstructural properties of food matrices to influencing bioaccessibility of bioactives and guides future development of functional food materials.

Infusion of trans-resveratrol in micron-scale grape skin powder for enhanced stability and bioaccessibility.

A novel delivery system using micron-scale grape skin powder (GSP) was developed that enhanced loading, stability and bioaccessibility of trans-resveratrol (trans-Res). Vacuum assisted infusion of GSP results in a high yield (~1 mg/g) of trans-Res and improved photostability of infused trans-Res in GSP exposed to UV-A light. The release of trans-Res from GSP was ~ 45% during gastric digestion and the total release in the intestinal phase during sequential digestion processes using low and high bile salts was ~ 70% and ~ 90%, respectively. Moreover, the release of endogenous polyphenols in GSP during simulated gastrointestinal digestion was similar to the release profile of infused resveratrol, suggesting strong interactions of infused resveratrol with the GSP matrix. In summary, this research illustrates a novel approach to utilize food by-products to enhance stability and bioaccessibility of bioactive compounds.

Synergistic inactivation of bacteria based on a combination of low frequency, low-intensity ultrasound and a food grade antioxidant.

This study evaluated a synergistic antimicrobial treatment using a combination of low frequency and a low-intensity ultrasound (LFU) and a food-grade antioxidant, propyl gallate (PG), against a model gram-positive (Listeria innocua) and the gram-negative bacteria (Escherichia coli O157:H7). Bacterial inactivation kinetic measurements were complemented by characterization of biophysical changes in liposomes, changes in bacterial membrane permeability, morphological changes in bacterial cells, and intracellular oxidative stress upon treatment with PG, LFU, and a combination of PG + LFU. Combination of PG + LFU significantly (>4 log CFU/mL, P < 0.05) enhanced the inactivation of both L. innocua and E. coli O157:H7 compared to PG or LFU treatment. As expected, L. innocua had a significantly higher resistance to inactivation compared to E. coli using a combination of PG + LFU. Biophysical measurements in liposomes, bacterial permeability measurements, and scanning electron microscope (SEM)-based morphological measurements show rapid interactions of PG with membranes. Upon extended treatment of cells with PG + LFU, a significant increase in membrane damage was observed compared to PG or LFU alone. A lack of change in the intracellular thiol content following the combined treatment and limited effectiveness of exogenously added antioxidants in attenuating the synergistic antimicrobial action demonstrated that oxidative stress was not a leading mechanism responsible for the synergistic inactivation by PG + LFU. Overall, the study illustrates synergistic inactivation of bacteria using a combination of PG + LFU based on enhanced membrane damage and its potential for applications in the food and environmental systems.

Ionic liquid-induced unprecedented size enhancement of aggregates within aqueous sodium dodecylbenzene sulfonate.

Physicochemical properties of aqueous micellar solutions may change in the presence of ionic liquids (ILs). Micelles help to increase the aqueous solubility of ILs. The average size of the micellar aggregates within aqueous sodium dodecylbenzene sulfonate (SDBS) is observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM) to increase in a sudden and drastic fashion as the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) is added. Similar addition of [bmim][PF(6)] to aqueous sodium dodecyl sulfate (SDS) results in only a slow gradual increase in average aggregate size. While addition of the IL [bmim][BF(4)] also gives rise to sudden aggregate size enhancement within aqueous SDBS, the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF(4)]), and inorganic salts NaPF(6) and NaBF(4), only gradually increase the assembly size upon their addition. Bulk dynamic viscosity, microviscosity, dipolarity (indicated by the fluorescent reporter pyrene), zeta potential, and electrical conductance measurements were taken to gain insight into this unusual size enhancement. It is proposed that bmim(+) cations of the IL undergo Coulombic attractive interactions with anionic headgroups at the micellar surface at all [bmim][PF(6)] concentrations in aqueous SDS; in aqueous SDBS, beyond a critical IL concentration, bmim(+) becomes involved in cation-π interaction with the phenyl moiety of SDBS within micellar aggregates with the butyl group aligned along the alkyl chain of the surfactant. This relocation of bmim(+) results in an unprecedented size increase in micellar aggregates. Aromaticity of the IL cation alongside the presence of sufficiently aliphatic (butyl or longer) alkyl chains on the IL appear to be essential for this dramatic critical expansion in self-assembly dimensions within aqueous SDBS.

Bioaccessibility of curcumin encapsulated in yeast cells and yeast cell wall particles.

This study evaluates the role of intracellular composition and integrity of cell walls in modulating the release and bioaccessibility of phytochemicals during simulated gastrointestinal digestion of cell-based carriers. Native yeast and yeast cell wall particles (YCWPs) were used as model cell-based carriers with distinct intracellular composition and curcumin was a model encapsulated bioactive. The results highlight the essential role of gastric treatments and the presence of bile salts in the release and bioaccessibility of encapsulated compound from cell-based carriers. YCWPs with significantly reduced intracellular contents have a significantly faster intestinal release after gastric digestion. Multimodal imaging approaches confirm the release of encapsulated curcumin in intestinal compartment without any significant changes in the cellular structure including cell walls. Based on these results, the study proposes a model that illustrate the significance of gastric digestion in influencing the release of curcumin during gastrointestinal digestion.

Carbon dots from roasted chicken accumulate in lysosomes and induce lysosome-dependent cell death.

Thermal processing may generate toxicants. Carbon dots (CDs) from baked foods are toxic to cells; however, their molecular mechanism is still unexplored to date. The present study investigated the effects of CDs from roasted chicken breasts on normal rat kidney (NRK) and Caco-2 cells. The average size of CDs heated at 200 °C and 300 °C was about 2.8 nm and 1.2 nm, respectively. The element and surface groups of CDs were analyzed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), respectively. It was confirmed that the CDs were internalized in lysosomes and induced apoptosis. Furthermore, Z-VAD-FMK did not decrease the rate of apoptosis. The acquired data further confirmed that these internalized CDs enlarged lysosomes, decreased the lysosomal enzyme degradation activity and increased the lysosomal pH value. An increase in the co-localization of RIPK3 in lysosomes in the CD-treated groups was observed. The CD treatment increased the protein level of receptor interaction protein 1 (RIPK1) and receptor interaction protein 3 (RIPK3). Overall, CDs from the baked chicken breast induced lysosomal membrane permeabilization and initiated lysosome-dependent cell death and necroptosis. Our results elucidated the toxic mechanism of CDs from baked chicken breast and implied that food thermal processing at a lower temperature is beneficial to human health.

Solvatochromic probe response within ionic liquids and their equimolar mixtures with tetraethylene glycol.

Synergism in a probe response within a mixture hints at the presence of strong interactions involving the solvent constituents of the mixture and possibly the probe. Unusual and rare "hyperpolarity" resulting from the synergism in probe response exhibited by ionic liquid (IL) mixtures with glycol family solvents is investigated in detail for equimolar mixtures of tetraethylene glycol (TEG) with many structurally different ILs using several UV-vis absorbance and fluorescence solvatochromic probes. Thirteen different ILs, of the same cation 1-butyl-3-methylimidazolium and different anions, of the same anion bis(trifluoromethylsulfonyl)imide and different cations, and of C2 methyl-substituted imidazolium cations, are used to assess the structural dependence of the IL on synergism exhibited by (IL + TEG) mixture. Responses from UV-vis absorbance probes are used to obtain ET [dipolarity/polarizability and/or H-bond donating (HBD) acidity] and Kamlet-Taft parameters [π* (dipolarity/polarizability), α (HBD acidity), and ß (HB accepting basicity)] within (IL + TEG) mixtures. The band I-to-band III fluorescence intensity ratio of dipolarity probe pyrene along with the lowest energy fluorescence band maxima of pyrene-1-carboxaldehyde (PyCHO, a probe for the permittivity of the medium), coumarin-153 and N,N-dimethyl-6-propionyl-2-naphthylamine PRODAN (neutral photoinduced charge-transfer fluorescence probes), and 6-p-toluidine-2-naphthalenesulfonic acid (TNS) and l-anilinonaphthalene-8-sulfonate (ANS) (ionic photoinduced charge-transfer fluorescence probes) are used to assess whether synergism is exhibited by (IL + TEG) equimolar mixtures. Probe responses within TEG equimolar mixtures with ILs are compared to those with common organic solvents. An attempt is made to establish a correlation between the synergism observed in the probe response within an (IL + TEG) mixture and the structural features of the cation and anion of the IL, such as acidity of the protons of the cation, aromaticity of the cation, and size, shape, and coordinating ability of the anion. It is established that the solvatochromism exhibited by the probes within (IL + TEG) mixtures is due to complex coupling of several different interactions and dynamical processes involving the probe as well as IL and TEG within the mixture.