Food-borne Nanoparticles Research Articles

Foodborne Carbon Dots Aggravate High-Fat-Diet-Induced Glucose Homeostasis Imbalance by Disrupting the Gut-Liver Axis.

Foodborne carbon dots (CDs) are generally produced during cooking and exist in food items. Generally, CDs are regarded as nontoxic materials, but several studies have gradually confirmed the cytotoxicity of CDs, such as oxidative stress, reduced cellular activity, apoptosis, etc. However, studies focusing on the health effects of long-term intake of food-borne CDs are scarce, especially in populations susceptible to metabolic disease. In this study, we reported that CDs in self-brewing beer had no effect on glucose metabolism in CHOW-fed mice but exacerbated high-fat-diet (HFD)-induced glucose metabolism disorders via the gut-liver axis. Chronic exposure to foodborne CDs increased fasting glucose levels and exacerbated liver and intestinal barrier damage in HFD-fed mice. The 16s rRNA sequencing analysis revealed that CDs significantly altered the gut microbiota composition and promoted lipopolysaccharide (LPS) synthesis-related KEGG pathways (superpathway of (Kdo)2-lipid A, Kdo transfer to lipid IVA Ill (Chlamydia), lipid IVA biosynthesis, and so on) in HFD-fed mice. Mechanically, CD exposure increased the abundance of Gram-negative bacteria (Proteobacteria and Desulfovibrionaceae), thus producing excessive endotoxin-LPS, and then LPS was transferred by the blood circulation to the liver due to the damaged intestinal barrier. In the liver, LPS promoted TLR4/NF-κB/P38 MAPK signaling, thus enhancing systemic inflammation and exacerbating HFD-induced insulin resistance. However, pretreating mice with antibiotics eliminated these effects, indicating a key role for gut microbiota in CDs exacerbating glucose metabolism disorders in HFD-fed mice. The finding herein provides new insight into the potential health risk of foodborne nanoparticles in susceptible populations by disturbing the gut-liver axis.

Visual foodborne nanoparticles for oral site-specific delivery of anthocyanins in the treatment of inflammatory bowel disease

The worldwide incidence and prevalence of inflammatory bowel disease (IBD) is increasing at an alarming rate, requiring the development of safe and effective therapeutic interventions. The use of oxidative stress and accelerated resolution of reactive oxygen species (ROS) has emerged as a potential new strategy for the management of inflammatory diseases. In this study, we described the development of a novel class of foodborne NPs-alginate-hyaluronic acid-anthocyanin nano-delivery system (FSHANPs) capable of visualizing inflammation-targeting sites and programmed release of anthocyanins in response to ROS surging from reactive lesion sites. FSHANPs are composed of abundant active functional groups on the surface of foodborne nanoparticles nano-self-assembled with alginate, hyaluronic acid, and anthocyanins. Alginate provided effective protection against enzyme degradation in the gastrointestinal tract of these anthocyanin molecules. The accumulation of FSHANPs at the site of the inflamed colon in IBD was contingent upon the fluorescence characteristics of the nanoparticles, which was subsequently followed by the specific recognition of the overexpressed CD44 protein by hyaluronic acid. Thus, facilitating the precise and targeted delivery of anthocyanins at the inflammatory site. Mechanically, FSHANPs containing anthocyanins effectively impeded the damage caused by ROS damage in RAW264.7 cells, alleviated lipopolysaccharide-induced apoptosis, and prevented the decline of mitochondrial membrane potential (p < 0.001). Additionally, the administration of FSHANPs reduced the expression of inflammatory factors, restored IBD-induced weight loss symptoms, and shortened colons due to the treatment with sodium dextran sulfate. Further studies showed that FSHANPs expedited intestinal mucosal healing and altered intestinal microbiota composition with increased abundance of beneficial bacteria such as Firmicutes and Muribaculaceae (p < 0.05). In conclusion, this study presents a promising therapy for IBD and a potential target for other inflammatory diseases, which can precisely deliver antioxidants into inflamed colon sites with oxidative stress-responsive and visualizing effects.

Physicochemical characterization, biodistribution, and bio‐effects of fluorescent carbon dots from roasted Spanish mackerel

AbstractNanoparticles with small sizes formed in the process of food thermal treatment have gained substantial attention due to their safety uncertainty and latent risks to human health. Herein, the physicochemical features of fluorescent carbon dots (CDs) from roasted Spanish mackerel were studied, it was found that the size distribution, fluorescence properties, surface groups, and formation process of CDs were highly dependent on the roasting time of Spanish mackerel. The interaction of CDs with digestive proteases resulted in the structural change and activity inhibition of proteases. When the concentration of CDs was 120 μg mL−1, the enzyme activity of pepsin and trypsin was reduced from 100% to 75.95% and 78.5%, respectively. The CDs caused static fluorescence quenching of pepsin and trypsin as confirmed by the fluorescence analysis. After oral administration, CDs can be transported to the main organs through the blood. The cytotoxicity assessment revealed that the cell viability decreased with the prolonging of roasting time. The CDs roasted at 230°C for 40 min showed a significant hemolytic effect even at a low concentration of 0.5 mg mL−1. Moreover, the cellular uptake level and pathway of CDs were significantly affected by blood protein adsorption. This study helps to evaluate the in vivo biodistribution, the interaction with proteases during gastrointestinal digestion, and the cellular uptake of CDs after transport through the blood, providing a theoretical basis for revealing the potential effects of foodborne nanoparticles.

The food additive titanium dioxide hinders intestinal production of TGF-β and IL-10 in mice, and long-term exposure in adults or from perinatal life blocks oral tolerance to ovalbumin.

Food hypersensitivities are increasing in industrialized countries, and foodborne nanoparticles (NPs) are suspected as co-factors in their aetiology. Food-grade titanium dioxide (fg-TiO2), a food colouring agent, is composed of NPs with immunomodulatory properties. We investigated whether fg-TiO2 may compromise the establishment of oral tolerance (OT) to food proteins using a model of OT induction to ovalbumin (OVA) in mice, and whether a perinatal exposure could trigger this effect. In pregnant mice fed a TiO2-enriched diet, ICP-MS and TEM-EDX analyses showed passage of TiO2 NPs into the foetus. When their weaned offspring were fed the same diet, a breakdown in OT to OVA was observed at adulthood, characterized by a high anti-OVA IgG production compared to controls. However, adult mice directly exposed to fg-TiO2 did not induce OT to OVA either, ruling out a developmental origin for these effects. When these mice were orally challenged with OVA, intestinal inflammation demonstrated hypersensitivity to OVA. In OVA-naïve mice, fg-TiO2 exposure impaired intestinal TGF-β and IL-10 production, of key role in OT induction and maintenance. These findings showed that long-term exposure to TiO2 as food additive alters anti-inflammatory cytokine profile, and leads to OT failure regardless of the timing of TiO2 exposure throughout life.

Food-Borne Nanocarriers for Calcium Delivery: A New Choice for Nutrient Supplements.

Calcium is considered as an important nutrient element for the maintenance of human health, and food-borne nanoparticles (FNs) produced during food processing may have potential as nanocarriers for calcium ion delivery. Beef is an important source of animal protein that has high protein and low fat content and is rich in a variety of amino acids; thus, beef may be a suitable material for the development of calcium nanocarriers. In this paper, FNs were synthesized from beef by one-step hydrothermal synthesis. The FNs had a spherical shape with a size of about 3.0 nm and emitted a bright blue fluorescence under 365 nm ultraviolet irradiation. The amino nitrogen atom and carboxyl oxygen atom of the functional groups on the surface of the FNs were the main binding sites for the chelation of Ca(II). The size of the FNs-Ca(II) complex was about 4.75 nm, and the specific signal peak of calcium at 3.7 keV was observed in its energy dispersive X-ray spectroscopy spectrum. The viability of cells treated with FNs-Ca(II) was more than 65%, while viability was only 60% after treatment with CaCl2. The results showed that the FNs from beef have great potential in calcium delivery for the development of a calcium supplement.

Change of Cell Toxicity of Food-Borne Nanoparticles after Forming Protein Coronas with Human Serum Albumin.

Nanoparticles (NPs) can form protein coronas with plasma proteins after entering the biological environment due to their surface adsorption ability. In this study, the effects of protein coronas of roast squid food-borne nanoparticles (FNPs) with human serum albumin (HSA) on the HepG-2 and normal rat kidney (NRK) cells were investigated. The hydrodynamic diameters of the HSA and HSA-FNPs were 8 and 13 nm, respectively. The cytotoxicity and cell membrane damage of FNPs to HepG-2 cells increased with the increase of roasting temperature. The presence of 4.78 × 10-3 mol/L FNPs increased the numbers of cellular necrosis and prolonged the G2 phase of the cell cycle. The formation of protein coronas of squid FNPs mitigated the autophagy phenomenon by FNPs on HepG-2 cells. Moreover, protein coronas reduced the mitochondrial membrane potential in the HepG-2 and NRK cells and the production of reactive oxygen species caused by FNPs. The abnormal contents of oxidative stress indicators such as glutathione, superoxide dismutase, malondialdehyde, and catalase in HepG-2 and NRK cells induced by FNPs were alleviated due to the presence of HSA. These results suggested that the protein coronas formed by HSA on FNPs mitigated the cytotoxicity compared with the bare FNPs, thus providing insights into the interaction of squid FNPs with HSA.

Assessment of Potential Toxicity of Onion-like Carbon Nanoparticles from Grilled Turbot Scophthalmus maximus L.

Although the presence of foodborne nanoparticles was confirmed in grilled fish in a previous study, the evaluation of potential health risks of these NPs was insufficient. In the present study, the potential toxicity of onion-like carbon nanoparticles (OCNPs) separated from grilled turbot Scophthalmus maximus L. was evaluated using mouse osteoblasts cells model and zebrafish (Danio rerio) model. Cytotoxicity evaluation revealed that the OCNPs penetrated into the MC3T3-E1 cells without arousing cell morphology changes. No evident apoptosis or damage of cells was observed with increasing OCNPs’ concentration to 20 mg/mL. In the hemolysis test, OCNPs did not show an obvious hemolysis effect on red blood cells. In the acute toxicity test, the LC50 value (212.431 mg/L) of OCNPs to zebrafish showed a weak acute toxicity. In subacute toxicity test, after exposure to OCNPs (30 mg/L, 40 mg/L) for 10 days, a significant increase of reactive oxygen species level of zebrafish was observed. Meanwhile, redundant ROS content caused inhibition to several antioxidant enzymes and induced lipid and protein peroxidation damages according to the upregulation of malondialdehyde and protein carbonyl levels. The chronic toxicity test results indicated that oxidative stress was only observed in the high concentration group of OCNPs-treated zebrafish.

Formation and biological effects of protein corona for food-related nanoparticles.

The rapid development of nanoscience and nanoengineering provides new perspectives on the composition of food materials, and has great potential for food biology research and applications. The use of nanoparticle additives and the discovery of endogenous nanoparticles in food make it important to elucidate in vivo safety of nanomaterials. Nanoparticles will spontaneously adsorb proteins during transporting in blood and a protein corona can be formed on the nanoparticle surface inside the human body. Protein corona affects the physicochemical properties of nanoparticles and the structure and function of proteins, which in turn affects a series of biological reactions. This article reviewed basic information about protein corona of food-related nanoparticles, elucidated the influence of protein corona on nanoparticles properties and protein structure and function, and discussed the effect of protein corona on nanoparticles in vivo. The effects of protein corona on nanoparticles transport, cellular uptake, cytotoxicity, and immune response were reviewed, and the reasons for these effects were also discussed. Finally, future research perspectives for food protein corona were proposed. Protein corona gives food nanoparticles a new identity, which makes proteins bound to nanoparticles undergo structural transformations that affect their recognition by receptors in vivo. It can have positive or negative impacts on cellular uptake and toxicity of nanoparticles and even trigger immune responses. Understanding the effects of protein corona have potential in evaluating the fate of the food-related nanoparticles, providing physicochemical and biological information about the interaction between proteins and foodborne nanoparticles. The review article will help to evaluate the safety of protein coronas formed on nanoparticles in food, and may provide fundamental information for understanding and controlling nanotoxicity.

Lactobacillus rhamnosus GG Ameliorated Long-Term Exposure to TiO2 Nanoparticles Induced Microbiota-Mediated Liver and Colon Inflammation and Fructose-Caused Metabolic Abnormality in Metabolism Syndrome Mice.

A huge number of titanium dioxide nanoparticles (TiO2 NPs) exist in confectionery foods, which is a high-risk factor for development of diet-induced metabolism syndrome (MetS). In this study, we built a high fructose drinking-induced MetS mouse model, and oral intake of 20 mg/kg TiO2 NPs was administered for 8 weeks. Significant pathological changes and inflammatory factors of overproduction were detected in the liver and colon. The 16S rDNA sequencing analysis results indicated that TiO2 NPs evidently and further perturbed the gut microbiota diversity, compositions, and KEGG pathways in MetS mice. Fecal microbiota transplant experiment proved that TiO2 NPs-altered gut microbiota drives liver and colon inflammation damage. More importantly, oral supplementation of Lactobacillus rhamnosus GG (LGG) ameliorated not only the TiO2 NPs-induced inflammation but also the fructose-caused metabolic abnormality. LGG recovered the gut dysbiosis and decreased the abundance of inflammation-related bacteria (Desulfovibrionaceae, Clostridia, and Proteobacteria), thereby protecting against TiO2 NPs-induced severe inflammation damage. Our study suggests the necessity of assessing the toxic effects of foodborne nanoparticles on the chronic disease population and potential usefulness of probiotics as prophylactic and therapeutic.

Construction and evaluation of an iron delivery system by ultra-small nanoparticles from roast sturgeon (Acipenser schrenckiid).

Nanoparticles were extensively applied as carriers for bioactive compound delivery to improve their bio-availability. In this study, we developed novel water-soluble and ultra-small food-borne nanoparticles (FNs) from roasting sturgeon as carriers for Fe(ii) delivery. The molecular interactions between FNs and Fe(ii) ions, and the digestion and absorption of the FN-Fe(ii) complex through the gastrointestinal system were investigated. The thermodynamic analysis revealed that the FNs spontaneously interacted with Fe(ii) having negative Gibbs free energy change. The data showed that approximately one FN can bind with four Fe(ii) (n = 4.23) through hydroxyl and amino groups. Flow cytometric analysis indicated that the FN-Fe(ii) had no effect on the cell viability at concentration <1 mg mL-1. The FN-Fe(ii) complex was stable in the digestive tract with a retention rate of 95.18% ± 3.11% after gastrointestinal digestion. Moreover, 1 μg mm-2 FN-Fe(ii) complex could cross the intestinal wall for Fe(ii) delivery. This research revealed that FNs produced from roasted sturgeon have the potential as biocompatible, efficient and stable nanocarriers for Fe(ii) nutritional delivery.

Zinc delivery system constructed from food-borne nanoparticles derived from Undaria pinnatifida.

Food-borne nanoparticles from Undaria pinnatifida (UPFNs) were prepared and successfully applied as nanocarriers for microelement zinc delivery. UPFNs were spherical nanoparticles with average sizes of about 4.07 ± 1.09 nm, which chelated with zinc ions through amino nitrogen and carboxyl oxygen atoms as characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and 1H nuclear magnetic resonance spectroscopy. Thermodynamic analysis revealed that the overall chelation process between UPFNs and zinc ions was a spontaneous enthalpy-driven endothermic reaction. Compared to zinc sulfate, UPFN-Zn2+ showed higher solubility both in phytic acid solution and the process of gastrointestinal digestion. Meanwhile, no obvious cytotoxicity was found in UPFNs and UPFN-Zn2+. Specifically, UPFN-Zn2+ could successfully rescue cell viability, DNA replication activity and restore cell proliferation ability in zinc-deficient cells induced by a specific zinc chelator TPEN. Overall, UPFNs might serve as efficient, stable, and safe nanocarriers for zinc delivery.

Molecular interaction of fluorescent carbon dots from mature vinegar with human hemoglobin: Insights from spectroscopy, thermodynamics and AFM

Foodborne nanoparticles have attracted considerable interest due to their distinctive fluorescence and physicochemical properties. The discovery of vinegar carbon dots (VCDs) has drawn our attention to study their effect on human plasma protein. Herein, spectral, constructional, morphological, and enzymatic activity assessments were carried out to investigate the interaction of VCDs with human hemoglobin (HHb). The intrinsic fluorescence of HHb was quenched significantly by the VCDs through a static quenching process. Furthermore, binding constants and important thermodynamic parameters were calculated, the negative enthalpy and entropy changes were accompanied by a negative Gibbs energy, which proposed the binding between VCDs with HHb was spontaneous. Moreover, negative enthalpy and entropy change corroborated the involvement of van der Waals force and hydrogen bonds in the binding process. Results from FTIR, atomic force microscopy and circular dichroism revealed change of HHB after binding with VCDs although their essential morphological features were unaffected. The esterase activity of HHb decreased after VCDs treatment in a dose-dependent manner, which further confirmed the effect of VCDs on HHb. The results offered detailed information about the interaction between VCDs and HHb.

Nanocorona Formation between Foodborne Nanoparticles Extracted from Roast Squid and Human Serum Albumin.

Foodborne nanoparticles (FNPs) produced by roasting have attracted the attention of people, owing to their safety risk to body health. Herein, we reported the formation, physicochemical properties, elemental composition, biodistribution, and binding with human serum albumin (HSA) of FNPs extracted from roast squid. The results showed that the FNP size gradually decreased from 4.1 to 2.3 nm as the roasting temperature changed from 190 to 250 °C. The main component elements of FNPs are carbon, oxygen, and nitrogen, and the carbon and nitrogen contents of FNPs increased with the roasting temperature rising. The surface of FNPs contained hydroxyl, amino, and carboxyl functional groups. The FNPs can emit fluorescence in ultraviolet light and show excitation-dependent emission behavior. Furthermore, it was found that the FNPs derived from roast squid could be accumulated in the stomach, intestine, and brain of BALB/c mice after oral feeding. Static fluorescence quenching of HSA was found by the Stern-Volmer equation and ultraviolet-visible spectrum analysis after interaction with the FNPs. After the addition of FNPs, the α-helix content of HSA decreased and the morphological height of HSA increased, which indicated that the FNPs could cause structural changes in HSA. The atomic force microscopy characterization showed the formation of nanocorona between FNPs and HSA.

Assessment of potential toxicity of foodborne fluorescent nanoparticles from roasted pork

Foodborne nanoparticles (NPs) refer to the nanostructures generated during food processing, rather than the man-made nano-structural additives that are added to improve the property of food. In this research, discovery of fluorescent NPs in roasted pork was reported at different temperature of 180, 230, and 280 °C. The size of the pork NPs was in the range of 5.93–7.49 nm. The FTIR and XPS analysis showed that the NPs are made up of graphitic carbon (sp2) and carbon defects (sp3), with abundant hydroxyl and carbonyl groups on the surface. The Ussing chamber test clearly showed the pork NPs had permeability passing through intestine. Significant fluorescence quenching of NPs was observed in the digestion in vitro. The bio-distribution of NPs in mice indicated that they obviously presented in liver, kidney and testis, even crossed the blood-brain barrier, entering into the brain. The oral administration of pork NPs at a dose of 2 g/kg mouse body weight did not caused obvious toxicity in BALB/c mice. However, significant influence of the NP exposure was observed on locomotion behaviors and lifespans in wild type Caenorhabditis elegans.

Hydrophilic Food-Borne Nanoparticles from Beef Broth as Novel Nanocarriers for Zinc

Food-borne nanoparticles (FNs) may be used as nanocarriers for metal ion chelation in micronutrient supplements. In this paper, the preparation and characterization of hydrophilic FNs were reported from beef broth cooked with a pressure cooker at 117 °C for different periods (30, 50, and 70 min) and their potential application as nanocarriers for zinc was investigated. The broth FNs are quasi-spherical with good water solubility and ultrasmall size, which can emit a strong sapphire color under 365 nm ultraviolet irradiation. X-ray photoelectron spectroscopy (XPS) analysis showed that there are carboxyl, amino, and hydroxyl groups on the FNs, which are useful for Zn(II) chelation. The vibration band of C═O at 1688 cm-1 in the infrared spectrum of FNs shifted to 1718 cm-1 after binding with Zn(II) ions, suggesting the participation of the carbonyl group in Zn(II) ion chelation. The appearance of Zn2p XPS peaks, at 1021.6 and 1045 eV for Zn(II)-FNs, clearly demonstrated the formation of Zn-O between the FNs and zinc ions. Biodistribution of FNs and the Zn(II)-FN complex in normal rat kidney cells demonstrated that they could easily enter normal rat kidney cells. A downfield was found for the signals of Zn(II)-FNs in 1H nuclear magnetic resonance spectroscopy and strongly suggested the binding of Zn(II) ions to FNs through carboxylic acid, hydroxyl, and amine groups. In addition, no obvious cytotoxicity was found for Zn(II)-FNs compared to zinc (ZnSO4) and commercial zinc gluconate. The results revealed that the FNs from beef broth may have a potential as nanocarriers for zinc chelation.

Carbon dots from roasted mackerel (scomberomorus niphonius) for free radical scavenging

Foodborne nanoparticles produced from food components during thermal processing have received attention due to their particular properties. Herein, the presence of fluorescent carbon dots (CDs) was reported from mackerel flesh roasted at 230 °C in an electronic oven, and the CD capability for free radical scavenging was investigated. The average size of the CDs was about 2.2 nm with a size distribution in the range of 0.9–3.5 nm as characterized with transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) showed that the mackerel CDs mainly contain C, N and O. Fourier transform infrared (FTIR) analysis showed the existence of hydroxyl, amino, and carboxyl groups on the mackerel CD surface. The fluorescence lifetime was about 9.1 ns. Two absorption peaks at 277 and 328 nm were observed in UV–vis spectra, which are assigned to the π-π* and n-π* charge-transfer, respectively. The mackerel CDs showed excellent photostability in various metal ion solutions and pH environment. In addition, these CDs exhibited strong dose-dependent scavenging capability for hydroxyl radicals (·OH) and methyl radicals (·CH3) produced from methylene blue (MB)/visible-light photosensitization system. The free radical scavenging properties make the mackerel CDs capable of protecting against oxidative stress after they are exposed to biosystem.

Food-borne nanocarriers from roast beef patties for iron delivery.

Food-borne nanoparticles (FNs) produced during thermal processing of food may have potential as nanocarriers for Fe(ii) supplements. In this paper, the FNs in beef patties roasted for different times (15, 30, and 45 minutes) and the binding between FNs and ferrous ions were studied. The size of FNs decreased from 7.5 to 3.0 nm with the increase of baking time, and the FNs emitted bright blue fluorescence under ultraviolet light irradiation. The combination of FNs with ferrous ions was by means of the amino, hydroxyl and carboxyl functional groups on the particles. Cell viability study showed that the Fe(ii)-FNs increased the apoptotic rate, but significantly decreased the necrosis rate, which led to an increase in the number of living cells. In addition, the Fe(ii)-FNs can easily enter the Caco-2 cytoplasm, but not the cellular nucleus. The FNs derived from beef patties with an ultra-small size, high water solubility and plenty of functional groups might be good candidates as nanocarriers for Fe(ii) delivery.

Characterization of Endogenous Nanoparticles from Roasted Chicken Breasts.

Emergence of endogenous nanoparticles in thermally processed food has aroused much attention due to their unique properties and potential biological impact. The aim of this study was to investigate the presence of fluorescence nanoparticles in roasted chicken breasts, elemental composition, physicochemical properties, and their molecular interaction with human serum albumin (HSA). Transmission electron microscopy analysis revealed that the foodborne nanoparticles from roasted chicken were nearly spherical with an average particle size of 1.7 ± 0.4 nm. The elemental analysis of X-ray photoelectron spectroscopy showed the composition of nanoparticles as 47.4% C, 25.8% O, and 26.1% N. The fluorescence of HSA was quenched by the nanoparticles following a static mode, and the molecular interaction of nanoparticles with HSA was spontaneous (Δ G0 < 0), where hydrogen bonding and van der Waals forces played an important role during HSA-nanoparticles complex stabilization through thermodynamic analysis by isothermal titration calorimetry. The principal location of the nanoparticles binding site on HSA was primarily in site I as determined by site-specific marker competition. The conformational of HSA was also changed and α-helical structure decreased in the presence of nanoparticles. Our studies revealed that fluorescent nanoparticles were produced after roasting of chicken breast at 230 °C for 30 min for the first time. The obtained nanoparticles can interact with HSA in a spontaneous manner, thus providing valuable insight into foodborne NPs as well as their effects to human albumin protein.

Fluorescent Carbon Dots Derived from Maillard Reaction Products: Their Properties, Biodistribution, Cytotoxicity, and Antioxidant Activity.

Food-borne nanoparticles have received great attention because of their unique physicochemical properties and potential health risk. In this study, carbon dots (CDs) formed during one of the most important chemical reactions in the food processing field, the Maillard reaction from the model system including glucose and lysine, were investigated. The CDs purified from Maillard reaction products emitted a strong blue fluorescence under ultraviolet light with a fluorescent quantum yield of 16.30%. In addition, they were roughly spherical, with sizes of around 4.3 nm, and mainly composed of carbon, oxygen, hydrogen, and nitrogen. Their surface groups such as hydroxyl, amino, and carboxyl groups were found to possibly enable CDs to scavenge DPPH and hydroxyl radicals. Furthermore, the cytotoxicity assessment of CDs showed that they could readily enter HepG2 cells while causing negligible cell death at low concentration. However, high CDs concentrations were highly cytotoxic and led to cell death via interference of the glycolytic pathway.

Fluorescent nanoparticles present in Coca-Cola and Pepsi-Cola: physiochemical properties, cytotoxicity, biodistribution and digestion studies

Foodborne nanoparticles (NPs) have drawn great attention due to human health concerns. This study reports the detection of the presence of fluorescent NPs, about 5 nm, in two of the most popular beverages, Coca-Cola (Coke) and Pepsi-Cola (Pepsi). The NPs contain H, C and O, three elements with a tunable emission and with a quantum yield of 3.3 and 4.3% for Coke and Pepsi, respectively. The presence of sp3-hybridized carbon atoms of alcohols and ethers bonds was confirmed by NMR analysis. The NPs can be taken up by living cells and accumulate within cell membrane and cytoplasm. Evaluation of the acute toxicity of the NPs revealed that the BALB/c mice appeared healthy after administration of a single dose of 2 g kg−1 body weight. Analysis of glutamate pyruvate transaminase (GPT), glutamic oxaloacetic transaminase (GOT), urea and creatinine showed that there were statistically, but not biologically, significant differences in some of these biochemical parameters between the test and control groups. No obvious organ damage or apparent histopathological abnormality was observed in the tested mice. The biodistribution study in major organs indicated that the NPs were easily accumulated in the digestive tract, and they were able to cross the blood–brain barrier and dispersed in the brain. In vitro digestion of the NPs showed a significant fluorescence quenching of the NPs. This work represents the first report of foodborne fluorescent NPs present in Coke and Pepsi, and provides valuable insights into physicochemical properties of these NPs and their toxicity characteristics both in vitro and in vivo.