Search

5'-Polynucleotide kinase such as T4 polynucleotide kinase (T4 PNK) may catalyze the phosphorylation of 5'-hydroxyl termini in nucleic acids, playing a crucial role in DNA replication, DNA recombination, and DNA damage repair. Here, we demonstrate for the first time single-molecule detection of PNK based on phosphorylation-directed recovery of fluorescence quenched by Au nanoparticle (AuNP) in combination with lambda exonuclease-mediated cleavage reaction. In the presence of PNK, the γ-phosphate group from adenosine triphosphate (ATP) is transferred to 5'-hydroxyl terminus, resulting in 5'-phosphorylation of the hairpin probe. The phosphorylated hairpin probes may function as the substrates of lambda exonuclease and enable the removal of 5' mononucleotides from the stem, leading to the unfolding of hairpin structure and the formation of binding probes. The resultant binding probes may specifically hybridize with the AuNP-modified capture probes, forming double-strand DNA (dsDNA) duplexes with 5'-phosphate groups as the substrates of lambda exonuclease and subsequently leading to the cleavage of capture probes and the liberation of Cy5 molecules and the binding probes. The released binding probes may further hybridize with new capture probes, inducing cycles of digestion-release-hybridization and consequently the release of numerous Cy5 molecules. Through simply monitoring Cy5 molecules with total internal reflection fluorescence (TIRF)-based imaging, PNK activity can be quantitatively measured. This assay is very sensitive with a limit of detection of 9.77 × 10-8 U/μL, and it may be further used to screen the PNK inhibitors and measure PNK in cancer cell extracts. [ABSTRACT FROM AUTHOR]

N 6 -Methyladenine (6mdA) and N 4 -methylcytosine (4mdC) are the two most dominant DNA modifications in both prokaryotes and eukaryotes, but standard hybridization-based techniques cannot be applied for the 6mdA/4mdC assay. Herein, we demonstrate the silver-coordinated Watson-Crick pairing-driven three-dimensional (3D) DNA walker for locus-specific detection of genomic 6mdA/4mdC at the single-molecule level. 6mdA-DNA and 4mdC-DNA can selectively hybridize with the binding probes (BP1 and BP2) to form 6mdA-DNA-BP1 and 4mdC-DNA-BP2 duplexes. The 6mdA-C/4mdC-A mismatches cannot be stabilized by Ag I , and thus, 18-nt BP1/BP2 cannot be extended by the catalysis of KF exonuclease. Through toehold-mediated strand displacement (TMSD), the signal probe (SP1/SP2) functionalized on the gold nanoparticles (AuNPs) can competitively bind to BP1/BP2 in 6mdA-DNA-BP1/4mdC-DNA-BP2 duplex to obtain SP1-18-nt BP1 and SP2-18-nt BP2 duplexes. The resulting DNA duplexes can act as the substrates of lambda exonuclease, leading to the cleavage of SP1/SP2 and the release of Cy3/Cy5 and 18-nt BP1/BP2. The released 18-nt BP1/BP2 can subsequently serve as the walker DNA, moving along the surface of the AuNP to activate dynamic 3D DNA walking and releasing abundant Cy3/Cy5. The released Cy3/Cy5 can be quantified by single-molecule imaging. This nanosensor exhibits high sensitivity with a limit of detection (LOD) of 9.80 × 10 -15 M for 6mdA-DNA and 9.97 × 10 -15 M for 4mdC-DNA. It can discriminate 6mdA-/4mdC-DNA from unmodified genomic DNAs, distinguish 0.01% 6mdA-/4mdC-DNA from excess unmethylated DNAs, and quantify 6mdA-/4mdC-DNA at specific sites in genomic DNAs of liver cancer cells and Escherichia coli plasmid cloning vector, providing a new platform for locus-specific analysis of 6mdA/4mdC in genomic DNAs.

Switchable materials have gained significant attention due to their potential applications in data storage, sensors, and switching devices. Two-dimensional (2D) hybrid perovskites have demonstrated promising prospects for designing switchable materials, where the dynamic motion of the organic components coupled with the distortion of the inorganic framework provides the driving force for triggering multifunctional switchable properties. Herein, through the H/F substitution strategy, we report a polar 2D hybrid lead-based perovskite, (4,4-DCA) 2 PbBr 4 (4,4-DCA = 4,4-difluorocyclohexylammonium) ( 1 ), which exhibits dual-stable behavior in a dielectric and second harmonic generation (SHG) response during the reversible phase transition process near the high Curie temperature T c ∼ 409 K. The phase transition temperature is significantly increased by 41 K compared to the corresponding non-fluorinated (CHA) 2 PbBr 4 (CHA = cyclohexylammonium). Remarkably, the material shows rare broad-band yellow emission under UV excitation, attributed to the induction of self-trapped exciton emission by the distortion of the [PbBr 6] 4- octahedra, as confirmed by the first-principles analysis. 1 also exhibited ferroelectricity with a saturation polarization value and a small coercive field. This study provides a new insight into the modification of multifunctional switchable materials through the H/F substitution strategy.

CpG methylation is one the most predominant epigenetic modification that has been recognized as a molecular-level biomarker for various human diseases. Taking advantage of methylation-dependent cleavage and encoding flexibility in nucleic acid functions and structures, we demonstrate the cooperative in situ assembly of G-quadruplex DNAzyme nanowires for one-step sensing of CpG methylation in human genomes. This nanodevice displays good specificity and high sensitivity with a limit of detection (LOD) of 0.565 aM in vitro and 1 cell in vivo . It can distinguish 0.001% CpG methylation level from excess unmethylated DNA, quantify different CpG methylation targets from diverse human cancer cells, and even discriminate CpG methylation expressions between lung tumor and precancerous tissues. Importantly, this nanodevice can be performed isothermally in one step within 2 h in a label-free manner without any bisulfite conversion, fluorescence tagging, and PCR amplification process, providing a new platform for genomic methylation-related clinical diagnosis and biomedical research.

Alkaline phosphatase (ALP) is an important hydrolase with crucial roles in biological processes, and the dysregulation of ALP may cause various human diseases. The conventional ALP assays usually involve cumbersome procedures with poor sensitivity. Herein, taking advantage of intrinsic superiorities of molecular beacons (MBs) and unique features of terminal deoxynucleotidyl transferase (TdT), we demonstrate for the first time the 3'-terminal repair-powered dendritic nanoassembly of polyadenine (A) MBs for one-step quantification of ALP in human serum. When ALP is present, it catalyzes 3'-terminal dephosphorylation of poly-A MBs to induce TdT-mediated template-free polymerization, generating long chains of polythymidine (T) sequences. The long poly-T chains can function as the anchoring templates to hybridize with many poly-A MBs, leading to the unfolding of loop structures and the dissociation of FAM/BHQ1 pairs (the 1st amplification stage). Subsequently, all 3'-hydroxylated poly-A MBs can be extended with the assistance of TdT to generate the branched long poly-T chains, leading to the hybridization of more poly-A MBs and the dissociation of more FAM/BHQ1 pairs (the 2nd amplification stage). Through multiple rounds of extension, assembly, and activation of poly-A MBs, dendritic DNA nanostructures are automatically formed, resulting in the dissociation of abundant fluorophores from the FAM/BHQ1 pairs to generate an exponentially amplified fluorescence signal (the n th amplification stage). This strategy possesses high sensitivity and excellent specificity, and the detection limit can reach 1 cell. Moreover, it can evaluate kinetic parameters, screen inhibitors, estimate cellular inhibition effects, and measure ALP in human serums.

Circulating miRNAs are a newly emerging class of noninvasive biomarkers, and the accurate quantification of their expression is essential to the biological research and early clinic diagnosis. Herein, we demonstrate the construction of a quencher-free cascade amplification system for highly sensitive detection of serum circulating miRNAs. The target miRNA can hybridize with the linear probe to induce the cyclic strand displacement amplification (SDA) (cycle I) for the production of the binding probes. The binding probe can subsequently react with the 2-aminopurine (2-AP)-hairpin probe to induce the recycling exonuclease cleavage of 2-AP-hairpin probes (cycle II), releasing the triggers and 2-AP molecules simultaneously. The released trigger can hybridize with the free linear probe to start new cycles I and II amplifications. Through multiple rounds of cascade amplifications, a large number of 2-AP molecules are released, generating an enhanced fluorescence signal. This method exhibits a large dynamic range of 8 orders of magnitude and a detection limit of 0.16 aM. It can differentiate a single-base mismatch in miR-486-5p, quantify miR-486-5p in lung cancer cells at various stages, and even discriminate the expressions of serum circulating miR-486-5p in healthy persons from that in nonsmall-cell lung carcinoma (NSCLC) patients. Moreover, this assay can be rapidly carried out in one step under isothermal condition in a label-free manner, holding promising applications in point-of-care diagnosis and prognosis of lung cancers.

The properties of supramolecular structures are highly dependent on their metal-centered building blocks and organic linkers, thus the search for novel systems will lead to new functions and applications for these unique assemblies. Here, two discrete triangular trimetallic sandwich building blocks were developed to construct supramolecular assemblies through coordination-driven self-assembly with organosulfur ligands. A series of tubelike (Tr 2 Pd 3 ) 4 L 6 assemblies (Tr = cycloheptatrienyl ring) were obtained from a discrete triangular tripalladium sandwich complex with bifunctional organosulfur ligands. By replacing the metal centers of the platinum analogue, the self-assembly process resulted in the clean formation of (Tr 2 Pt 3 ) 2 L 3 triple helicates instead of tubelike species. The trimetallic sandwich building blocks were also shown to form face-capped (Tr 2 M 3 ) 4 L 4 (M = Pd or Pt) tetrahedral cages when trifunctional organosulfur ligands were used. The supramolecular assemblies were comprehensively analyzed by X-ray crystallography. A metal-cluster-induced structural transformation between (Tr 2 Pd 3 ) 4 L 4 tubes and (Tr 2 Pt 3 ) 2 L 3 triple helicates was observed. Furthermore, the face-capped (Tr 2 Pd 3 ) 4 L 4 cage possesses a tetrahedral cavity allowing the encapsulation of a series of guests.

A multifunctional supramolecular assembly was successfully constructed by the host-guest complexation of doubly positively charged adamantane (ADA) with β-CD-modified hexabenzocoronene and the π-stacking of coronene with mitoxantrone, which was characterized by transmission electron microscopy, scanning electron microscopy, dynamic light-scattering, and zeta potential experiments. Possessing a small size and rigid backbone coronene center, the water-soluble biocompatible supramolecular assembly has intracellular imaging abilities. Moreover, after the ester group of ADA was hydrolyzed into a carboxyl group, the positively charged quaternary amine strand converted into a zwitterion structure, which realized the controlled plasmid DNA binding and release. Besides, the cytotoxicity experiments showed that the supramolecular assembly possesses slightly lower toxicity and a slightly higher anticancer activity than free drug. We believe that this work might present a convenient method for synergetic cancer treatment., Competing Interests: The authors declare no competing financial interest.

Molecular self-replication is a fundamental function of all living organisms with the capability of templating and catalyzing its own synthesis, and it plays important roles in prebiotic chemical evolution and effective synthetic machineries. However, the construction of the self-replication system in vitro remains a great challenge and its application for biosensing is rare. Here, we demonstrate for the first time the construction of an in vitro enzymatic nucleic acid self-replication system and its application for amplified sensing of human 8-oxoguanine DNA glycosylase (hOGG1) based on autocatalytic self-replication-driven cascaded recycling amplification. In this strategy, hOGG1 excises 8-oxoguanine (8-oxoG) to unfold the hairpin substrate, activating the autonomous biocatalytic process with molecular beacons (MBs) as both the fuels for producing nucleic acid templates and the generators for signal output, leading to the continuous replication of biocatalytic nucleic acid templates and the repeated cleavage of MBs for an enhanced fluorescence signal. This strategy exhibits an extremely low detection limit of 4.3 × 10 -7 U/μL and a large dynamic range of 5 orders of magnitude from 1 × 10 -6 to 0.05 U/μL. Importantly, it can be applied for the detection of enzyme kinetic parameters, the screening of hOGG1 inhibitors, and the quantification of hOGG1 activity in even 1 single lung cancer cell, providing a new approach for biomedical research and clinical diagnosis.

Uracil-DNA glycosylase (UDG) is an important base excision repair (BER) enzyme responsible for the repair of uracil-induced DNA lesion and the maintenance of genomic integrity, while the aberrant expression of UDG is associated with a variety of cancers. Thus, the accurate detection of UDG activity is essential to biomedical research and clinical diagnosis. Here, we develop a fluorescent method for ultrasensitive detection of UDG activity using excision repair-initiated enzyme-assisted bicyclic cascade signal amplification. This assay involves (1) UDG-actuated uracil-excision repair, (2) excision repair-initiated nicking enzyme-mediated isothermal exponential amplification, (3) ribonuclease H (RNase H)-induced hydrolysis of signal probes for generating fluorescence signal. The presence of UDG enables the removal of uracil from U·A pairs and generates an apurinic/apyrimidinic (AP) site. Endonuclease IV (Endo IV) subsequently cleaves the AP site, resulting in the break of DNA substrate. The cleaved DNA substrate functions as both a primer and a template to initiate isothermal exponential amplification, producing a large number of triggers. The resultant trigger may selectively hybridize with the signal probe which is modified with FAM and BHQ1, forming a RNA-DNA heterogeneous duplex. The subsequent hydrolysis of RNA-DNA duplex by RNase H leads to the generation of fluorescence signal. This assay exhibits ultrahigh sensitivity with a detection limit of 0.0001 U/mL, and it can even measure UDG activity at the single-cell level. Moreover, this method can be applied for the measurement of kinetic parameters and the screening of inhibitors, thereby providing a powerful tool for DNA repair enzyme-related biomedical research and clinical diagnosis.

DNA glycosylase is an initiating enzyme of cellular base excision repair pathway which is responsible for the repair of various DNA lesions and the maintenance of genomic stability, and the dysregulation of DNA glycosylase activity is associated with a variety of human pathology. Accurate detection of DNA glycosylase activity is critical to both clinical diagnosis and therapeutics, but conventional methods for the DNA glycosylase assay are usually time-consuming with poor sensitivity. Here, we demonstrate the base-excision-repair-induced construction of a single quantum dot (QD)-based sensor for highly sensitive measurement of DNA glycosylase activity. We use human 8-oxoguanine-DNA glycosylase 1 (hOGG1), which is responsible for specifically repairing the damaged 8-hydroxyguanine (8-oxoG, one of the most abundant and widely studied DNA damage products), as a model DNA glycosylase. In the presence of biotin-labeled DNA substrate, the hOGG1 may catalyze the removal of 8-oxo G from 8-oxoG·C base pairs to generate an apurinic/apyrimidinic (AP) site. With the assistance of apurinic/apyrimidinic endonuclease (APE1), the cleavage of the AP site results in the generation of a single-nucleotide gap. Subsequently, DNA polymerase β incorporates a Cy5-labeled dGTP into the DNA substrate to fill the gap. With the addition of streptavidin-coated QDs, a QD-DNA-Cy5 nanostructure is formed via specific biotin-streptavidin binding, inducing the occurrence of fluorescence resonance energy transfer (FRET) from the QD to Cy5. The resulting Cy5 signal can be simply monitored by total internal reflection fluorescence (TIRF) imaging. The proposed method enables highly sensitive measurement of hOGG1 activity with a detection limit of 1.8 × 10(-6) U/μL. Moreover, it can be used to measure the enzyme kinetic parameters and detect the hOGG1 activity in crude cell extracts, offering a powerful tool for biomedical research and clinical diagnosis.

Lipid peroxidation in oil-in-water (o/w) emulsions leads to rancidity and carcinogen formation. This work attempted to protect lipid droplets of emulsions from peroxidation via manipulation of the emulsions' interface framework using dual-function zein/CH complex particles (ZCPs). ZCP with intermediate wettability was fabricated via a simple antisolvent approach. Pickering emulsions were produced via a simple and inexpensive shear-induced emulsification technique. ZCP was irreversibly anchored at the oil-water interface to form particle-based network architecture therein, producing ultrastable o/w Pickering emulsions (ZCPEs). ZCPE was not labile to lipid oxidation, evidenced by low lipid hydroperoxides and malondialdehyde levels in the emulsions after thermally accelerated storage. The targeted accumulation of curcumin, a model antioxidant, at the interface was achieved using the ZCP as interfacial vehicle, forming antioxidant shells around dispersed droplets. The oxidative stability of ZCPEs was further improved. Interestingly, no detectable hexanal peak appeared in headspace gas chromatography of the Pickering emulsions. The novel interfacial architecture via the combination of steric hindrance from ZCP-based membrane and interfacial cargo of curcumin endowed the emulsions with favorable oxidative stability. This study opens a promising pathway for producing antioxidant emulsions via the combination of Pickering stabilization mechanism and interfacial delivery of antioxidant.

Protein kinases play crucial roles in intracellular signal transduction and metabolic pathways, and the monitoring of protein kinase activity is essential to the understanding of fundamental biochemical processes and the clinical diagnosis. Here, we demonstrate the phosphorylation-directed assembly of a single quantum dot (QD)-based nanosensor for sensitive detection of cAMP-dependent protein kinase (PKA). This assay involves (1) the PKA-directed simultaneous phosphorylation and biotinylation of cyanine 5 (Cy5)-labeled substrate peptides, (2) the assembly of phosphorylated and biotinylated peptides onto the surface of the QD, and (3) the illumination of Cy5 by means of fluorescence resonance energy transfer (FRET) between the QD and Cy5. With an adenosine triphosphate (ATP) analogue, γ-biotin-ATP, as the phosphoryl donor, the PKA-catalyzed phosphorylation reaction incorporates the biotin-conjugated phosphate group into the substrate peptides to form the biotinylated peptides. The biotin entity subsequently drives the assembly of peptides onto the surface of streptavidin-functionalized QD to form the sandwiched Cy5-peptide-QD nanostructure, enabling the occurrence of FRET between the QD and Cy5. The FRET signal can be easily recorded by either the conventional fluorescence spectrometer or the total internal reflection fluorescence (TIRF) microscope. In contrast, the absence of PKA cannot lead to the formation of Cy5-peptide-QD complex and no Cy5 signal can be detected. This protein kinase-actuated FRET assay is straightforward, without the involvement of either washing or separation steps, and has a significant advantage of high sensitivity with a detection limit of 9.3 × 10(-6) U/μL. Moreover, this method can be used to estimate the half-maximal inhibitory concentration (IC50) value of PKA inhibitor H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride) and to monitor forskolin (Fsk)/3-isobutyl-1-methylxanthine (IBMX)-triggered activation of PKA in cell lysates, thus holding great potential for further applications in protein kinase-related biological researches and drug discovery.

This paper describes the successful preparation of a protein-based Pickering emulsion, with superior stability against both coalesence and creaming, through a novel strategy of facilitating the formation of protein particles and small molecular weight surfactant complexes; these complexes are able to overcome multiple challenges including limited solubility, poor diffusive mobility, and low interfacial loading. Soluble complexes of water-insoluble corn protein, zein colloidal particles, and surfactant sodium stearate (SS) were fabricated by simple ultrasonication. Gel trapping technology combined with SEM was applied to characterize the adsorbed particles monolayer at the oil-water interface; results revealed an enhanced adsorption and targeted accumulation of zein particles at the interface with the increase of SS concentration. Partial unfolding of zein particles modified by SS above its critical complexation concentration triggered the aggregation and close packing of particles at the oil-water interface and endowed a steric barrier against the coalescence of oil droplets. Moreover, protein-based oil gels without oil leakage were obtained by one-step freeze-drying of the zein-stabilized Pickering emulsions, which could be developed to a viable strategy for structuring liquid oils into semisolid fats without the use of saturated or trans fats.

Human telomerase is a ribonucleoprotein complex which adds the repeats of TTAGGG on the telomeric ends of chromosomal DNA. Even though the vast majority of human cancers express telomerase activity, most human somatic cells lack the telomerase activity; consequently, telomerase has been regarded as both a biomarker for early cancer diagnosis and a therapeutic target. Here we develop a simple, rapid and highly sensitive method for the detection of telomerase activity at the single-cell level using telomeres-induced two-stage isothermal amplification-mediated chemiluminescence assay. In the presence of telomerase, the telomere repeats of (TTAGGG)n are added to the 3' end of telomerase substrate primer, which can be converted to the template of strand displacement amplification (SDA) for the generation of short oligonucleotides, catalytic DNAzymes, and the telomere repeats of (TTAGGG)n. The short oligonucleotide might function as a new trigger to bind the free telomerase substrate primer and consequently initiate an isothermally exponential amplification reaction (EXPAR), generating a large number of catalytic DNAzymes. Both the DNAzymes and the G-rich telomeric repeat units can interact with hemin to form the catalytic hemin-G-quadruplex nanostructures, which can catalyze the generation of amplified chemiluminescence signals in the presence of luminol and H2O2. While in the absence of telomerase, the two-stage isothermal amplification cannot be initiated, and no chemiluminescence signal is observed. Owing to the high amplification efficiency of two-stage isothermal amplification as well as the high sensitivity and wide dynamic range of the chemiluminescence assay, the proposed method can sensitively measure the synthetic telomerase product TPC8 with a detection limit of as low as 0.1 aM and a large dynamic range of 10 orders of magnitude from 0.1 aM to 1 nM and can even detect the telomerase activity from a single HeLa cancer cell without the need for any labeled DNA probes. The proposed method can be further used to screen the anticancer drugs and might provide a promising approach for the discovery of new anticancer drugs.

This work attempted to develop novel high barrier zein/SC nanoparticle (ZP)-stabilized emulsion films through microfluidic emulsification (ZPE films) or in combination with solvent (ethyl acetate) evaporation techniques (ZPE-EA films). Some physical properties, including tensile and optical properties, water vapor permeability (WVP), and surface hydrophobicity, as well as the microstructure of ZP-stabilized emulsion films were evaluated and compared with SC emulsion (SCE) films. The emulsion/solvent evaporation approach reduced lipid droplets of ZP-stabilized emulsions, and lipid droplets of ZP-stabilized emulsions were similar to or slightly lower than that of SC emulsions. However, ZP- and SC-stabilized emulsion films exhibited a completely different microstructure, nanoscalar lipid droplets were homogeneously distributed in the ZPE film matrix and interpenetrating protein-oil complex networks occurred within ZPE-EA films, whereas SCE films presented a heterogeneous microstructure. The different stabilization mechanisms against creaming or coalescence during film formation accounted for the preceding discrepancy of the microstructures between ZP-and SC-stabilized emulsion films. Interestingly, ZP-stabilized emulsion films exhibited a better water barrier efficiency, and the WVP values were only 40-50% of SCE films. A schematic representation for the formation of ZP-stabilized emulsion films was proposed to relate the physical performance of the films with their microstructure and to elucidate the possible forming mechanism of the films.

We report a new type of single InAs quantum dot (QD) embedded at the junction of gold-free branched GaAs/AlGaAs nanowire (NW) grown on silicon substrate. The photoluminescence intensity of such QD is ~20 times stronger than that from randomly distributed QD grown on the facet of straight NW. Sharp excitonic emission is observed at 4.2 K with a line width of 101 μeV and a vanishing two-photon emission probability of g(2)(0) = 0.031(2). This new nanostructure may open new ways for designing novel quantum optoelectronic devices.

A new reductase, CgKR2, with the ability to reduce ethyl 2-oxo-4-phenylbutyrate (OPBE) to ethyl (R)-2-hydroxy-4-phenylbutyrate ((R)-HPBE), an important chiral precursor for angiotensin-converting enzyme (ACE) inhibitors, was discovered. For the first time, (R)-HPBE with >99% ee was produced via bioreduction of OPBE at 1 M without external addition of cofactors. The space-time yield (700 g·L(-1)·d(-1)) was 27 times higher than the highest record., (© 2012 American Chemical Society)

We evaluated the influence of heat treatment on interfacial properties (adsorption at the oil-water interface and dilatational rheology of interfacial layers) of soy protein isolate. The related structural properties of protein affecting these interfacial behaviors, including protein unfolding and aggregation, surface hydrophobicity, and the state of sulfhydryl group, were also investigated. The structural and interfacial properties of soy protein depended strongly on heating temperature (90 and 120 °C). Heat treatment at 90 °C induced an increase in surface hydrophobicity due to partial unfolding of protein, accompanied by the formation of aggregates linked by disulfide bond, and lower surface pressure at long-term adsorption and similar dynamic interfacial rheology were observed as compared to native protein. Contrastingly, heat treatment at 120 °C led to a higher surface activity of the protein and rapid development of intermolecular interactions in the adsorbed layer, as evidenced by a faster increase of surface pressure and dilatational modulus. The interfacial behaviors of this heated protein may be mainly associated with more flexible conformation and high free sulfhydryl group, even if some exposed hydrophobic groups are involved in the formation of aggregates. These results would be useful to better understand the structure dependence of protein interfacial behaviors and to expand utilization of heat-treated protein in the formulation and production of emulsions.

The present investigation aimed to expand the knowledge of the in vitro bioaccessibility of fatty acids and tocopherol from natural soybean oil body emulsions stabilized with different concentrations of ι-carrageenan. Several physicochemical parameters including proteolysis of the interfacial layer, interfacial composition, and microstructure were evaluated with regard to their impact on the bioaccessibility of fatty acids and tocopherol. Results from simulated human digestion in vitro indicated that the bioaccessibility of total fatty acids and tocopherol decreased (62.7-8.3 and 59.7-19.4%, respectively) with the increasing concentration of ι-carrageenan. During the in vitro digestion procedure, ι-carrageenan affected physicochemical properties of the emulsions, thereby controlling the release of fatty acids and tocopherol. These results suggested that soybean oil body emulsions stabilized with ι-carrageenan could provide natural emulsions in foods that were digested at a relatively slow rate, the important physiological consequence of which might be increasing satiety.

The concept of hormesis has generated considerable interest within the environmental and toxicological communities over the past decades. However, toxicological evaluation and prediction of hormesis in mixtures are challenging and only just unfolding. The hormetic effects of ten ionic liquids (ILs), singly and in mixtures in the ratios of their individual EC50, EC10, EC0, and ECm (maximal stimulatory effect concentration), on luciferase luminescence were determined by using microplate toxicity analysis. There was good agreement between the effects observed and predicted by concentration addition (CA) for all four mixtures. This evidence supports the use of CA model as a default approach for assessing the combined effect of chemicals at the molecular level. Focusing on the selected points of the concentration-response curves (CRCs) of mixtures, the mixtures of IL chemicals mixed at concentrations that individually showed stimulatory effects could produce inhibitory or no effects, and the mixture of IL chemicals mixed at concentrations that individually showed no effects could produce significant inhibitory effect. The three interesting phenomena in mixture hormesis may have important implications for current risk assessment practices.

Two new kinds of tetrahydrobenzo[b]imidazo[3,2,1-ij][1,8]naphthyridine derivatives have been successfully synthesized by cascade reactions including Knoevenagel condensation, aza-ene reaction, imine-enamine tautomerization, cyclocondensation, and intramolecular S(N)Ar of precursors 2-(2-chloroaroyl)methyleneimidazolidines with aromatic aldehydes and ethyl acetoacetate or Meldrum's acid under mild conditions, respectively. These studies highlighted the concept of a substrate-design approach to the development of novel multicomponent reactions by simply incorporating an o-halo group into the aryl ring of 2-benzoylmethyleneimidazolidine as new synthons. In this domino reaction, at least six different active sites are involved; two C-C bonds, two C-N bonds, and two new rings are constructed with all reactants efficiently utilized in the chemical transformation.