Search Results (13)

Due to their lipophilicity and low content, the major sesame oleosin allergens, Ses i 4 and Ses i 5, are challenging to identify using conventional techniques. Then, a novel unlabeled electrochemical immunosensor was developed to detect the potential allergic activity of sesame oleosins. The voltammetric immunosensor was constructed using a composite of gold nanoparticles (AuNPs), polyethyleneimine (PEI), and multi-walled carbon nanotubes (MWCNTs), which was synthesized in a one-pot process and modified onto a glass carbon electrode to enhance the catalytic current of the oxygen reduction reaction. The oleosin antibody was then directed and immobilized onto the surface of the electrode, which had been modified with streptavidin (SPA), through the fragment crystallizable (Fc) region of the antibody. Under optimized conditions, the immunosensor exhibited a linear response within a detection range of 50 to 800 ng/L, with detection limits of 0.616 ng/L for Ses i 4 and 0.307 ng/L for Ses i 5, respectively. The immunosensor demonstrated excellent selectivity and stability, making it suitable for the quantification of sesame oleosins. The comparative analysis of various detection methods for sesame allergens was conducted, revealing that the immunosensor achieved a wide detection range and low limit of detection (LOD). Compared to traditional enzyme-linked immunosorbent assay (ELISA), the immunosensor successfully quantified the allergenicity potential of Ses i 4 and Ses i 5 in roasted sesame seeds at temperatures of 120 °C, 150 °C, and 180 °C. This innovative method offers a new perspective for the rapid quantification of sesame oleosins in foods and real-time monitoring of allergic potential, providing significant advancements in the field of food allergy detection. Full article

A novel microfluidic ractopamine (RAC) detection platform consisting of a microfluidic RAC chip and a smart analysis device is proposed for the determination of RAC concentration in meat samples. This technology utilizes gold nanoparticles (AuNPs) modified with glutamic acid (GLU) and polyethyleneimine (PEI) to measure RAC concentration in food products. When RAC is present, AuNPs aggregate through hydrogen bonding, causing noticeable changes in their optical properties, which are detected using a self-built UV–visible micro-spectrophotometer. Within the range of 5 to 80 ppb, a linear relationship exists between the absorbance ratio (A_693nm/A_518nm) (Y) and RAC concentration (X), expressed as Y = 0.0054X + 0.4690, with a high coefficient of determination (R² = 0.9943). This method exhibits a detection limit of 1.0 ppb and achieves results within 3 min. The practical utility of this microfluidic assay is exemplified through the evaluation of RAC concentrations in 50 commercially available meat samples. The variance between concentrations measured using this platform and those determined via liquid chromatography–tandem mass spectrometry (LC-MS/MS) is less than 8.33%. These results underscore the viability of the microfluidic detection platform as a rapid and cost-effective solution for ensuring food safety and regulatory compliance within the livestock industry. Full article

A novel electrochemical aptasensor was prepared for the simultaneous determination of aflatoxin B1 (AFB1) and ochratoxin A (OTA). Composites of Au nanoparticles and polyethyleneimine-reduced graphene oxide (AuNPs/PEI-RGO) with good electrical conductivity and high specific surface area were employed as the supporting substrate, demonstrating the ability to provide more binding sites for aptamers and accelerate the electron transfer. Aptamers were immobilized on a AuNPs/PEI-RGO surface to specifically recognize AFB1 and OTA. A metal–organic framework of UiO-66-NH₂ served as the signal carrier to load metal ions of Cu²⁺ and Pb²⁺, which facilitated the generation of independent current peaks and effectively improved the electrochemical signals. The prepared aptasensor exhibited sensitive current responses for AFB1 and OTA with a linear range of 0.01 to 1000 ng/mL, with detection limits of 6.2 ng/L for AFB1 and 3.7 ng/L for OTA, respectively. The aptasensor was applied to detect AFB1 and OTA in cereal samples, achieving results comparable with HPLC-MS, with recovery results from 92.5% to 104.1%. With these merits of high sensitivity and good selectivity and stability, the prepared aptasensor proved to be a powerful tool for evaluating contaminated cereals. Full article

This research analyzed the mechanisms of work and modified a colorimetric nanosensor to make it more cost-effective for the detection of Escherichia coli (E. coli) in water. The base nanosensors modified herein rely on a competitive binding detection mechanism, where positively charged gold nanoparticles coated with polyethyleneimine (PEI-AuNPs) preferably bind to negatively charged E. coli in the presence of β-galactosidase ($\mathsf{\beta }$-Gal) enzymes and chlorophenol red β-d-galactopyranosides (CPRG). The positive surface charge of the nanoparticle, rather than nanoparticle composition or type of chemical coating on its surface, was hypothesized herein as the governing factor for the nanosensor functionality. Thus, positively charged nanoparticles and polymers were tested as potential alternatives for gold nanoparticles for detecting E. coli. Positively charged silver and iron oxide nanoparticles coated with branched PEI detected E. coli as low as 10⁵ and 10⁷ colony-forming units per milliliter (CFU/mL), respectively. Furthermore, the branched PEI polymer itself (without nanomaterial) detected E. coli at 10⁷ CFU/mL. These findings suggest that the positive charge, rather than the nanoparticle type was likely responsible for the detection of E. coli using the competitive binding approach. Therefore, other types of recyclable and cost-effective nanomaterials and polymers can be developed for E. coli detection using this rapid colorimetric sensing technique. Full article

Environmental monitoring and the detection of antibiotic contaminants require expensive and time-consuming techniques. To overcome these challenges, gold nanoparticle-mediated fluorometric “turn-on” detection of Polymyxin B (PMB) in an aqueous medium was undertaken. The molecular weight of polyethyleneimine (PEI)-dependent physicochemical tuning of gold nanoparticles (PEI@AuNPs) was achieved and employed for the same. The three variable molecular weights of branched polyethyleneimine (MW 750, 60, and 1.3 kDa) molecules controlled the nano-geometry of the gold nanoparticles along with enhanced stabilization at room temperature. The synthesized gold nanoparticles were characterized through various advanced techniques. The results revealed that polyethyleneimine-stabilized gold nanoparticles (PEI@AuNP-1-3) were 4.5, 7.0, and 52.5 nm in size with spherical shapes, and the zeta potential values were 29.9, 22.5, and 16.6 mV, respectively. Accordingly, the PEI@AuNPs probes demonstrated high sensitivity and selectivity, with a linear relationship curve over a concentration range of 1–6 μM for polymyxin B. The limit of detection (LOD) was calculated as 8.5 nM. This is the first unique report of gold nanoparticle nano-geometry-dependent FRET-based turn-on detection of PMB in an aqueous medium. We believe that this approach would offer a complementary strategy for the development of a highly sophisticated and advanced sensing system for PMB and act as a template for the development of new nanomaterial-based engineered sensors for rapid antibiotic detection in environmental as well as biological samples. Full article

Magnetic–plasmonic nanoparticles (NPs) have attracted great interest in many fields because they can exhibit more physical and chemical properties than individual magnetic or plasmonic NPs. In this work, we synthesized Au- or Ag-decorated Fe₃O₄ nanoparticles coated with PEI (Fe₃O₄-PEI-M (M = Au or Ag) NPs) using a simple method. The influences of the plasmonic metal NPs’ (Au or Ag) coating density on the magnetic and plasmonic properties of the Fe₃O₄-PEI-M (M = Au or Ag) NPs were investigated, and the density of the plasmonic metal NPs coated on the Fe₃O₄ NPs surfaces could be adjusted by controlling the polyethyleneimine (PEI) concentration. It showed that the Fe₃O₄-PEI-M (M = Au or Ag) NPs exhibited both magnetic and plasmonic properties. When the PEI concentration increased from 5 to 35 mg/mL, the coating density of the Au or Ag NPs on the Fe₃O₄ NPs surfaces increased, the corresponding magnetic intensity became weaker, and the plasmonic intensity was stronger. At the same time, the plasmonic resonance peak of the Fe₃O₄-PEI-M (M = Au or Ag) NPs was red shifted. Therefore, there was an optimal coverage of the plasmonic metal NPs on the Fe₃O₄ NPs surfaces to balance the magnetic and plasmonic properties when the PEI concentration was between 15 and 25 mg/mL. This result can guide the application of the Fe₃O₄-M (M = Au or Ag) NPs in the biomedical field. Full article

The differences in urinary proteins could provide a novel opportunity to distinguish the different types of drug-induced kidney injury (DIKI). In this research, Au nanoparticles–polyethyleneimine (AuNPs–PEI) and the three fluorophore-labeled proteins (FLPs) have been constructed as a multichannel fluorescent array sensor via electrostatic interaction, which was used to detect the subtle changes in urine collected from the pathological state of DIKI. Once the urine from different types of DIKI was introduced, the binding equilibrium between AuNPs–PEI and FLPs would be broken due to the competitive binding of urinary protein, and the corresponding fluorescence response pattern would be generated. Depending on the different fluorescence response patterns, the different types of DIKI were successfully identified by principal component analysis (PCA) and linear discriminant analysis (LDA). Accordingly, the strategy was expected to be a powerful technique for evaluating the potential unclear mechanisms of nephrotoxic drugs, which would provide a promising method for screening potential renal-protective drugs. Full article

Nanomedicines based on inorganic nanoparticles have grown in the last decades due to the nanosystems’ versatility in the coating, tuneability, and physical and chemical properties. Nonetheless, concerns have been raised regarding the immunotropic profile of nanoparticles and how metallic nanoparticles affect the immune system. Cationic polymer nanoparticles are widely used for cell transfection and proved to exert an adjuvant immunomodulatory effect that improves the efficiency of conventional vaccines against infection or cancer. Likewise, gold nanoparticles (AuNPs) also exhibit diverse effects on immune response depending on size or coatings. Photothermal or photodynamic therapy, radiosensitization, and drug or gene delivery systems take advantage of the unique properties of AuNPs to deeply modify the tumoral ecosystem. However, the collective effects that AuNPs combined with cationic polymers might exert on their own in the tumor immunological microenvironment remain elusive. The purpose of this study was to analyze the triple-negative breast tumor immunological microenvironment upon intratumoral injection of polyethyleneimine (PEI)–AuNP nanocomposites (named AuPEI) and elucidate how it might affect future immunotherapeutic approaches based on this nanosystem. AuPEI nanocomposites were synthesized through a one-pot synthesis method with PEI as both a reducing and capping agent, resulting in fractal assemblies of about 10 nm AuNPs. AuPEI induced an inflammatory profile in vitro in the mouse macrophage-like cells RAW264.7 as determined by the secretion of TNF-α and CCL5 while the immunosuppressor IL-10 was not increased. However, in vivo in the mouse breast MET-1 tumor model, AuPEI nanocomposites shifted the immunological tumor microenvironment toward an M2 phenotype with an immunosuppressive profile as determined by the infiltration of PD-1-positive lymphocytes. This dichotomy in AuPEI nanocomposites in vitro and in vivo might be attributed to the highly complex tumor microenvironment and highlights the importance of testing the immunogenicity of nanomaterials in vitro and more importantly in vivo in relevant immunocompetent mouse tumor models to better elucidate any adverse or unexpected effect. Full article

The study of the surface of membrane coatings constructed with adsorbed coronavirus (COV) was described to test their suitability for the antiviral activity for application in personal protective and medical equipment. The nanocoating based on polyethyleneimine (PEI) or polystyrene sulfonate (PSS) with metallic nanoparticles incorporated was investigated using the AFM technique. Moreover, the functioning of human lung cells in a configuration with the prepared material with the adsorbed coronavirus was studied using microscopic techniques and flow cytometry. The mean values of the percentage share of viable cells compared with the control differed by a maximum of 22%. The results showed that PEI and PSS membrane layer coatings, modified with chosen metallic nanoparticles (AuNPs, AgNPs, CuNPs, FeNPs) that absorb COV, could support lung cells’ function, despite the different distribution patterns of COV on designed surfaces as well as immobilized lung cells. Therefore, the developed membrane nanocoatings can be recommended as material for biomedical applications, e.g., medical equipment surfaces to reduce coronavirus spreading, as they adsorb COV and simultaneously maintain the functioning of the eukaryotic cells. Full article

Facile detection methods for mycotoxins with high sensitivity are of great significance to prevent potential harm to humans. Herein, a label-free amperometric immunosensor based on a 3-D interconnected carbon nanofibers (CNFs) network coupled with well-dispersed Au nanoparticles (AuNPs) is proposed for the quantitative determination of aflatoxin B₁ (AFB₁) in wheat samples. In comparison to common carbon nanotubes (CNTs), the CNFs network derived from bacterial cellulose biomass possesses a unique hierarchically porous structure for fast electrolyte diffusion and a larger electrochemical active area, which increases the peak current of differential pulse voltammetry curves for an immunosensor. Combined with AuNPs that are incorporated into CNFs by using linear polyethyleneimine (PEI) as a soft template, the developed Au@PEI@CNFs-based immunosensor showed a good linear response to AFB₁ concentrations in a wide range from 0.05 to 25 ng mL⁻¹. The limit of detection was 0.027 ng mL⁻¹ (S/N = 3), more than three-fold lower than that of an Au@PEI@CNTs-based sensor. The reproducibility, storage stability and selectivity of the immunosensor were proved to be satisfactory. The developed immunosensor with appropriate sensitivity and reliable accuracy can be used for the analysis of wheat samples. Full article

Use of multicellular spheroids in studies of nanoparticles (NPs) has increased in the last decade, however details of NPs interaction with spheroids are poorly known. We synthesized AuNPs (12.0 ± 0.1 nm in diameter, transmission electron microscopy (TEM data) and covered them with bovine serum albumin (BSA) and polyethyleneimine (PEI). Values of hydrodynamic diameter were 17.4 ± 0.4; 35.9 ± 0.5 and ±125.9 ± 2.8 nm for AuNPs, AuBSA-NPs and AuPEI-NPs, and Z-potential (net charge) values were −33.6 ± 2.0; −35.7 ± 1.8 and 39.9 ± 1.3 mV, respectively. Spheroids of human hepatocarcinoma (HepG2) and human embryo kidney (HEK293) cells (Corning ® spheroid microplates CLS4515-5EA), and monolayers of these cell lines were incubated with all NPs for 15 min–4 h, and fixed in 4% paraformaldehyde solution. Samples were examined using transmission and scanning electron microscopy. HepG2 and HEK2893 spheroids showed tissue-specific features and contacted with culture medium by basal plasma membrane of the cells. HepG2 cells both in monolayer and spheroids did not uptake of the AuNPs, while AuBSA-NPs and AuPEI-NPs readily penetrated these cells. All studied NPs penetrated HEK293 cells in both monolayer and spheroids. Thus, two different cell cultures maintained a type of the interaction with NPs in monolayer and spheroid forms, which not depended on NPs Z-potential and size. Full article

It is of great significance for dynamic monitoring of foods in storage or during the transportation process through on-line detecting trimethylamine (TMA). Here, TMA were sensitively detected by Au-modified hierarchical porous single-crystalline ZnO nanosheets (HPSCZNs)-based sensors. The HPSCZNs were synthesized through a one-pot wet-chemical method followed by an annealing treatment. Polyethyleneimine (PEI) was used to modify the surface of the HPSCZNs, and then the PEI-modified samples were mixed with Au nanoparticles (NPs) sol solution. Electrostatic interactions drive Au nanoparticles loading onto the surface of the HPSCZNs. The Au-modified HPSCZNs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS), respectively. The results show that Au-modified HPSCZNs-based sensors exhibit a high response to TMA. The linear range is from 10 to 300 ppb; while the detection limit is 10 ppb, which is the lowest value to our knowledge. Full article

Herein we report a simple and green synthesis of smart Au and Ag@Au nanocomposite particles using poly(N-isopropylacrylamide)/polyethyleneimine (PNIPAm/PEI) core-shell microgels as dual reductant and templates in an aqueous system. The nanocomposite particles were synthesized through a spontaneous reduction of tetrachloroauric (III) acid to gold nanoparticles at room temperature, and in situ encapsulation and stabilization of the resultant gold nanoparticles (AuNPs) with amine-rich PEI shells. The preformed gold nanoparticles then acted as seed nanoparticles for further generation of Ag@Au bimetallic nanoparticles within the microgel templates at 60 °C. These nanocomposite particles were characterized by TEM, AFM, XPS, UV-vis spectroscopy, zeta-potential, and particle size analysis. The synergistic effects of the smart nanocomposite particles were studied via the reduction of p-nitrophenol to p-aminophenol. The catalytic performance of the bimetallic Ag@Au nanocomposite particles was 25-fold higher than that of the monometallic Au nanoparticles. Finally, the controllable catalytic activities of the Au@PNIPAm/PEI nanocomposite particles were demonstrated via tuning the solution pH and temperature. Full article