Abstract: A method of preparing a flavor composition containing D-allulose includes: (1) weighing D-allulose, mogroside, steviol glycoside and trichlorosucrose in parts by weight, and mixing them evenly to obtain a mixed powder; (2) degassing, compressing, and rolling the mixed powder, and extruding the raw materials into flakes; and (3) crushing and granulating the shaped flakes to obtain the flavor composition. D-allulose is used as the main raw material, and added high-intensity sweeteners as auxiliary raw materials. After the raw materials are mixed evenly, dry granulation is adopted, and the powder is degassed and pre-compressed by using the crystal water in the raw materials, and squeezed by a hydraulic roller to form a bonding force between the various sweetener molecules to form flakes, and the flakes are processed by processes such as crushing and granulating to obtain the flavor composition granules containing D-allulose with the various sweeteners integrated uniformly as a whole.

Abstract: A method for preparing a dual-functional hybrid thin-film for self-calibration detection of tumor-derived exosomes is disclosed. A dual-functional hybrid thin-film, aptamer-BPNSs/Fc/ZIF-67/ITO, is constructed by facile self-assembly of a cobalt-based metal-organic framework (ZIF-67) composite doped with black phosphorus nanosheets (BPNSs), an aptamer and ferrocene (Fc) on an indium tin oxide (ITO) electrode. Methylene blue (MB) labeled aptamer specifically binds to CD63 protein to precisely capture protein. The protein is a specific biomolecule carried by breast cancer MCF-7 cell exosome, and realizes the detection of the tumor cell exosome. A self-calibration sensor for quantitative detection of the tumor exosome is constructed by using MB as a response signal and Fc as a reference.

Abstract: A method for preparing a ratiometric electrochemical miR3123 aptasensor based on a copper-based metal-organic framework (Cu-MOF) composite doped with black phosphorus nanosheets (BPNSs) and thionine (TH) is provided. TH/Cu-MOF is prepared by reacting TH with Cu-MOF precursor, and BPNSs/TH/Cu-MOF is prepared by drop coating the BPNSs and drop coated onto an electrode. A ferrocene (Fc)-labeled single-stranded DNA aptamer is adsorbed on the BPNSs to prepare aptamer-BPNSs/TH/Cu-MOF. Target molecule miR3123 is bonded with the single-stranded DNA aptamer Fc-DNA, Fc-DNA is forced to escape from the BPNSs. Electrochemical signals of Fc are, therefore, weakened while TH signals are slightly affected. The ratiometric electrochemical miR3123 aptasensor is constructed by fitting a linear relationship between peak current intensity ratios IFc/ITH and concentrations of the miR3123.

Abstract: A method for preparing a dual-functional hybrid thin-film for self-calibration detection of tumor-derived exosomes is disclosed. A dual-functional hybrid thin-film, aptamer-BPNSs/Fc/ZIF-67/ITO, is constructed by facile self-assembly of a cobalt-based metal-organic framework (ZIF-67) composite doped with black phosphorus nanosheets (BPNSs), an aptamer and ferrocene (Fc) on an indium tin oxide (ITO) electrode. Methylene blue (MB) labeled aptamer specifically binds to CD63 protein to precisely capture protein. The protein is a specific biomolecule carried by breast cancer MCF-7 cell exosome, and realizes the detection of the tumor cell exosome. A self-calibration sensor for quantitative detection of the tumor exosome is constructed by using MB as a response signal and Fc as a reference.

Abstract: A method for preparing a ratiometric electrochemical miR3123 aptasensor based on a copper-based metal-organic framework (Cu-MOF) composite doped with black phosphorus nanosheets (BPNSs) and thionine (TH) is provided. TH/Cu-MOF is prepared by reacting TH with Cu-MOF precursor, and BPNSs/TH/Cu-MOF is prepared by drop coating the BPNSs and drop coated onto an electrode. A ferrocene (Fc)-labeled single-stranded DNA aptamer is adsorbed on the BPNSs to prepare aptamer-BPNSs/TH/Cu-MOF. Target molecule miR3123 is bonded with the single-stranded DNA aptamer Fc-DNA, Fc-DNA is forced to escape from the BPNSs. Electrochemical signals of Fc are, therefore, weakened while TH signals are slightly affected. The ratiometric electrochemical miR3123 aptasensor is constructed by fitting a linear relationship between peak current intensity ratios IFc/ITH and concentrations of the miR3123.

Abstract: A method for preparing a nanohybrid used for ratiometric fluorescence and ratiometric electrochemical sensing simultaneously is provided. Surface-aminated (—NH2) SiO2 nanospheres encapsulating an electroactive material A or B are prepared and conjugated with surface-carboxylated (—COOH) carbon dots (CDs) or gold nanoclusters (AuNCs) to prepare a conjugate, and the conjugate is conjugated with a DNA aptamer terminated with —NH2. Ions or biomolecules are added to two types of DNA-conjugate dispersions, and ratiometric florescence sensing is realized by fitting the linear relationship between ratiometric fluorescent peak intensity ICDs/IAuNCs and a specific ion concentration or a specific biomolecule concentration.

Abstract: A method for preparing a nanohybrid used for ratiometric fluorescence and ratiometric electrochemical sensing simultaneously is provided. Surface-aminated (—NH2) SiO2 nanospheres encapsulating an electroactive material A or B are prepared and conjugated with surface-carboxylated (—COOH) carbon dots (CDs) or gold nanoclusters (AuNCs) to prepare a conjugate, and the conjugate is conjugated with a DNA aptamer terminated with —NH2. Ions or biomolecules are added to two types of DNA-conjugate dispersions, and ratiometric florescence sensing is realized by fitting the linear relationship between ratiometric fluorescent peak intensity IcDs/IAuNcs and a specific ion concentration or a specific biomolecule concentration.

Abstract: A method for preparing an upconversion-luminescence flexible hybrid membrane for visual detection of tumor markers is provided. Metal ion doped black phosphorus quantum dots (M-BPQDs) are prepared by adopting ultrasonic and solvothermal processes; mesoporous SiO2 grows on the surfaces of the M-BPQDs and amination modification is performed; the M-BPQDs are connected with carboxylated single-stranded DNA1; receptor molecules enter pores; single-stranded DNA2 aptamers and the DNA1 are combined due to base complementation to encapsulate receptors in the pores; and an M-BPQDs probe is prepared. DNA1 terminal-SH and a composite membrane are formed by assembling polymethyl methacrylate-polyimide-gold nanoparticles in a layer-by-layer manner bound by Au—S bonds, and the membrane and the probe are connected to construct the flexible hybrid membrane. The new flexible hybrid membrane is simple and inexpensive to prepare and is highly sensitive.

Abstract: A method for preparing an upconversion-luminescence flexible hybrid membrane for visual detection of tumor markers is provided. Metal ion doped black phosphorus quantum dots (M-BPQDs) are prepared by adopting ultrasonic and solvothermal processes; mesoporous SiO2 grows on the surfaces of the M-BPQDs and amination modification is performed; the M-BPQDs are connected with carboxylated single-stranded DNA1; receptor molecules enter pores; single-stranded DNA2 aptamers and the DNA1 are combined due to base complementation to encapsulate receptors in the pores; and an M-BPQDs probe is prepared. DNA1 terminal-SH and a composite membrane are formed by assembling polymethyl methacrylate-polyimide-gold nanoparticles in a layer-by-layer manner bound by Au—S bonds, and the membrane and the probe are connected to construct the flexible hybrid membrane. The new flexible hybrid membrane is simple and inexpensive to prepare and is highly sensitive.

Abstract: A method for preparing a ratiometric electrochemical aptasensor for vanillin based on an aptamer-gold nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified electrode includes, dripping ZIF-8 nanocomposite doped with ferrocene and Ketjenblack on the surface of the bare glassy carbon electrode, and immersing this modified electrode in the chloroauric acid solution. The cyclic voltammetry is employed to scan and electrodeposit gold nanoparticles to obtain the gold nanoparticle-deposited ZIF-8 nanocomposite. The aptamer of vanillin is attached to gold nanoparticles via Au—S bonds to construct an aptamer-coupled nanocomposite sensing platform. Then, the electrochemical curves in the presence of different vanillin concentrations are measured, the linear relationship between the ratios of the current peak intensities of ferrocene and vanillin and the molar concentrations of vanillin is fitted, and the ratiometric electrochemical aptasensor for vanillin is constructed.

Abstract: A method for preparing a ratiometric fluorescent probe for cymoxanil based on a double-emission quantum dot-silver nanoparticle complex, wherein, the double-emission carbon quantum dots and the silver nanoparticles are prepared, and the inner filter effect occurring between the double-emission carbon quantum dots and the dispersed silver nanoparticles causes the blue fluorescence quenching of the carbon quantum dots. However, the specific binding of cymoxanil to silver nanoparticles causes the silver nanoparticles to accumulate, and then the inner filter effect occurring between the double-emission carbon quantum dots and the dispersed silver nanoparticles causes the green fluorescence quenching of carbon quantum dots. In this regard, the linear relationship between the intensity ratio of two fluorescent emission peaks of carbon quantum dots and the molar concentration of cymoxanil is established, and the ratiometric fluorescent probe for cymoxanil is constructed.

Abstract: A method for preparing a ratiometric fluorescent probe for cymoxanil based on a double-emission quantum dot-silver nanoparticle complex, wherein, the double-emission carbon quantum dots and the silver nanoparticles are prepared, and the inner filter effect occurring between the double-emission carbon quantum dots and the dispersed silver nanoparticles causes the blue fluorescence quenching of the carbon quantum dots. However, the specific binding of cymoxanil to silver nanoparticles causes the silver nanoparticles to accumulate, and then the inner filter effect occurring between the double-emission carbon quantum dots and the dispersed silver nanoparticles causes the green fluorescence quenching of carbon quantum dots. In this regard, the linear relationship between the intensity ratio of two fluorescent emission peaks of carbon quantum dots and the molar concentration of cymoxanil is established, and the ratiometric fluorescent probe for cymoxanil is constructed.

Abstract: A method for preparing a ratiometric electrochemical aptasensor for vanillin based on an aptamer-gold nanoparticle-ferrocene-Ketjenblack-ZIF-8 nanocomposite modified electrode includes, dripping ZIF-8 nanocomposite doped with ferrocene and Ketjenblack on the surface of the bare glassy carbon electrode, and immersing this modified electrode in the chloroauric acid solution. The cyclic voltammetry is employed to scan and electrodeposit gold nanoparticles to obtain the gold nanoparticle-deposited ZIF-8 nanocomposite. The aptamer of vanillin is attached to gold nanoparticles via Au—S bonds to construct an aptamer-coupled nanocomposite sensing platform. Then, the electrochemical curves in the presence of different vanillin concentrations are measured, the linear relationship between the ratios of the current peak intensities of ferrocene and vanillin and the molar concentrations of vanillin is fitted, and the ratiometric electrochemical aptasensor for vanillin is constructed.