•The probe is capable of detecting SO32- within 30 s.•The probe exhibits high sensitivity with the detection limit as low as 85 nM.•The probe displays sufficiently satisfactory selective response to sulfite ions among various interferential anions.•The probe can be successfully applied to detect sulfite in its vitro studies with cancer cells.A solo turn-on fluorescent probe based on the coumarin and selective deprotection of the levulinate group has been developed for detection of sulfite with rapid response time (only a few seconds). The probe 1 exhibited sufficiently satisfactory selective response to sulfite among various interferential anions, and high sensitivity with the detection limit as low as 85 nM. Upon interaction with sulfite, the probe 1 rendered turn-on response by exhibiting prominently bluish-green fluorescence under physiological condition. The mechanism of the interaction has been well confirmed by the changes in ultraviolet visible (UV-vis) absorption spectra and electrospray ionization (ESI) mass spectra. Importantly, probe 1 has been successfully applied to detect sulfite in its vitro studies with cancer cells.Download high-res image (234KB)Download full-size image

•A novel fluorescence probe with simple structure for relay recognition of Fe3+ and PO43− was synthesized.•The proposed method exhibited high selectivity and sensitivity, short respond time, low detection limit.•The fluorescence probe can also be used for biological cell imaging.A novel fluorescent probe XDS based on 4-methylumbelliferone and 2-picolylamine platforms has been designed and synthesized, which behaves fast relay recognition of Fe3+ and PO43− via a fluorescence “on−off−on” response signal. Probe XDS exhibited very high sensitivity and unique selectivity for Fe3+ over other common metal ions, and the detection limit of was 3.2 × 10−7 M. Moreover, the addition of the PO43− ions could cause the recovery of fluorescence. This relay recognition feature of probe XDS has potential applications in the determination of trace amount of Fe3+ and PO43− in environmental systems. Interestingly, fluorescence imaging experiments demonstrated that the probe XDS can also be used to monitoring the intracellular Fe3+ in RAMOS cells.Download high-res image (137KB)Download full-size image

•A novel type of multifunctional chemosensors to Al3+, Zn2+ and temperature was reported.•The chemosensor can distiguish Al3+ and Zn2+ in their mixed solution by controlling the response time.•The detection limit of Al3+ and Zn2+ ions at 40 °C can be decreased to ∼2.14 and ∼8.71 ppb, respectively.•The chemosensor showed a high stability and feasibility for analysis in biological samples.In this paper, a novel type of responsive double hydrophilic block copolymer (DHBC)-based multifunctional chemosensors to Al3+, Zn2+ and temperature was designed and prepared. The well-defined DHBCs with Al3+ and Zn2+-reactive thermosensitive block (copolymer fluorescence chemosensor), poly(ethylene oxide)-b-poly(N-isopropylacrylamide-co-SHMA)65(PEO113-b-P(NIPAM-co-SHMA)65, Mn = 13.2 kDa, Mw/Mn = 1.09), were synthetized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The novel well water-soluble copolymer fluorescence chemosensor could selectively recognize Al3+ (blue fluorescence) and Zn2+ (green fluorescence) by the difference of the fluorescence color. Moreover, this copolymer fluorescence chemosensor has the ability to selective recognition Al3+ or Zn2+ in their mixed solution by controlling the fluorescence response time. The detection limit of 0.1 g/L copolymer fluorescence chemosensor for the analysis of Al3+ and Zn2+ ions at 25 °C were calculated to be ∼5.23 and ∼11.99 ppb, respectively. PEO113-b-P(NIPAM-co-SHMA) can self-assemble into micelles with P(NIPAM-co-SHMA) block as core and well-solvated PEO block as coronas when heating to the lower critical solution temperature (LCST), and the detection limit of Al3+ and Zn2+ ions at 40 °C can be decreased to ∼2.14 and ∼8.71 ppb, respectively. Furthermore, the copolymer fluorescence chemosensor has been successfully applied to detect Al3+ and Zn2+ in biological samples.Download high-res image (155KB)Download full-size image

We developed an efficient and mild method for the preparation of boronic acid-functionalized magnetic nanoparticles (MNPs), and the selective separation of fructose from a sample solution was demonstrated for the first time. A modified hydrothermal method was chosen to prepare the naked Fe3O4 MNPs, and then the Fe3O4@SiO2 MNPs were synthesized by a sol–gel reaction. After that, the thiol-coated Fe3O4 MNPs were synthesized by a sol–gel reaction with an organosilicon coupling agent. Finally, the thiol groups on the surface of the MNPs served as clickable sites to react with 4-vinylphenylboronic acid (VPBA) via a thiol–ene (TE) click reaction to obtain the final MNPs with a high density of boronic acid ligands immobilized on the surface. It is known that phenylboronic acid ligands on Fe3O4@SiO2@VPBA MNPs can form stable five- or six-membered cyclic esters with cis-diol-containing molecules. In this work, the click-Fe3O4 MNPs with a mean diameter of 195 nm exhibited high selectivity and binding capacity towards fructose. Also, the adsorption efficiency of fructose could reach ≈96% under optimum adsorption conditions. In addition, the adsorption efficiency of fructose was about six times higher than that of glucose in a fructose–glucose aqueous solution, suggesting that the resultant Fe3O4@SiO2@VPBA MNPs had higher affinity for fructose under the interference of competing glucose. Reusability is also an important factor of affinity adsorbents, and the adsorption capacity of Fe3O4@SiO2@VPBA MNPs was virtually unchanged after six cycles of reuse.

The cloud point (CP) values of aqueous solutions of the triblock copolymer L64 were determined in the absence and presence of five salting-out salts (K2SO4, Na2SO4, (NH4)2SO4, K2CO3, K2HPO4) at different concentrations. All the five salts could decrease the CP values and form aqueous two phase systems (ATPSs) with L64. A notable phase inversion phenomenon occurred with the increasing salt concentrations and the phase inversion points were found. The salt-rich phase transferred from the top phase to the bottom phase because of the change of density. Liquid–liquid equilibrium (LLE) data of these ATPSs were measured at 45 °C, respectively. The consistency of the tie-lines was verified by using the empirical equations from the Othmer-Tobias and Bancroft correlation. The effects on the cloudy behavior and phase separation depended on the salting-out ability. The results showed that the salting-out ability of the cations followed the order: Na+ > K+ > NH4+NH4+; the anions followed the order: HPO42−HPO42− > SO42−SO42− > CO32−CO32−. It could be concluded that using the Gibbs free energy of hydration of the ions (ΔGHyd) to estimate salting-out ability was not suitable for all of the ATPSs.

The cloud point of thermosensitive triblock polymer L61, poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO), was determined in the presence of various electrolytes (K2HPO4, (NH4)3C6H5O7, and K3C6H5O7). The cloud point of L61 was lowered by the addition of electrolytes, and the cloud point of L61 decreased linearly with increasing electrolyte concentration. The efficacy of electrolytes on reducing cloud point followed the order: K3C6H5O7 > (NH4)3C6H5O7 > K2HPO4. With the increase in salt concentration, aqueous two-phase systems exhibited a phase inversion. In addition, increasing the temperature reduced the concentration of salt needed that could promote phase inversion. The phase diagrams and liquid–liquid equilibrium data of the L61-K2HPO4/(NH4)3C6H5O7/K3C6H5O7 aqueous two-phase systems (before the phase inversion but also after phase inversion) were determined at T = (25, 30, and 35) °C. Phase diagrams of aqueous two-phase systems were fitted to a four-parameter empirical nonlinear expression. Moreover, the slopes of the tie-lines and the area of two-phase region in the diagram have a tendency to rise with increasing temperature. The capacity of different salts to induce aqueous two-phase system formation was the same order as the ability of salts to reduce the cloud point.

•The simultaneous ATPE and saponification reaction of chlorophyll was investigated.•Conventional method was compared with simultaneous ATPE and saponification.•Effects of parameters on the amount of sodium chlorophyllin were studied.•The top system of the ATPS was used to prepare sodium copper chlorophyllin.Simultaneous aqueous two-phase extraction and saponification reaction of chlorophyll from silkworm excrement was investigated in this study, and it was compared with the saponification reaction followed by aqueous two-phase extraction (ATPE) method. The results indicate that it is better to use the simultaneous aqueous two-phase extraction and saponification reaction method than other method. The effects of different parameters on the amount of sodium chlorophyllin in the top system of the ethanol–NaOH aqueous two-phase system (ATPS) were studied, including salt concentration, saponification temperature and time. When the NaOH concentration was 0.4 g/ml, saponification temperature and time were 333.15 K and 2 h respectively, the amount of sodium chlorophyllin in the top system reached its maximum in the investigated range. Further, the top system of the ethanol–NaOH ATPS was taken out and used to prepare sodium copper chlorophyllin, and the absorbance ratio (A405.00nm/A627.00nm) was 3.67.

•Binodal and tie-lines data of the investigated ATPSs were determined.•Appropriate equations were used to correlate the binodal curves and the tie-lines data.•Temperature and salt effects on forming an ATPS were investigated.•The phase-forming ability of hydrophilic alcohols was discussed by both the phase diagrams and EEV theory.Binodal data for ethanol, 2-propanol and 1-propanol + sodium hydroxide (NaOH) + water systems were experimentally determined at 283.15, 298.15 and 313.15 K, respectively. An empirical equation was used to correlate the binodal data. On the basis of the empirical equation with binodal data and the lever rule, the tie-lines data for the investigated systems at 298.15 K were obtained via the MATLAB and then correlated by Othmer-Tobias and Bancroft equations. Temperature and salting-out effects on this type of ATPS were investigated. It was found that an increase in temperature leads to an expansion of the two-phase area. The salting-out ability of NaF is stronger than that of NaOH. Additionally, the phase-forming abilities of the investigated hydrophilic alcohols were discussed by both the effective excluded volume (EEV) of the investigated salt and the location of the binodal curves of the investigated systems. The phase-forming abilities of the investigated hydrophilic alcohols follow the order: 1-propanol > 2-propanol > ethanol.

Binodal data for the ethanol/propan-1-ol/propan-2-ol−dipotassium 2,3-dihydroxybutanedioate aqueous two-phase system (ATPS), the propan-2-ol−disodium 2,3-dihydroxybutanedioate/diammonium 2,3-dihydroxybutanedioate ATPS, and the ethanol−potassium sodium 2,3-dihydroxybutanedioate ATPS were determined at 298.15 K. An empirical equation was used to correlate binodal data, and it showed satisfactory accuracy in binodal data fitting for all of the determined systems. The phase-separation abilities of the investigated salts and the water-miscible alcohols were compared by the plotting of binodal curves in mass fraction. The phase-separation abilities of the investigated alcohols are in the order propan-1-ol > propan-2-ol > ethanol, and those of salts are in the order disodium 2,3-dihydroxybutanedioate > potassium sodium 2,3-dihydroxybutanedioate > dipotassium 2,3-dihydroxybutanedioate > diammonium 2,3-dihydroxybutanedioate. However, the two-phase area of the investigated alcohol−dipotassium 2,3-dihydroxybutanedioate ATPS is higher than that of the alcohol−disodium 2,3-dihydroxybutanedioate/potassium sodium 2,3-dihydroxybutanedioate/diammonium 2,3-dihydroxybutanedioate ATPS. The salting-out abilities of the common cations (K+, Na+, and NH4+) were discussed by comparing their effective excluded volume (EEV) in the propan-2-ol−water component solvent and the binodal curves plotted in molality. They are in the order Na+ ≈ K+ > NH4+.

In this paper, the feasibility of applying the water-miscible alcohol–salt aqueous two-phase system to separate small molecular antibiotics in aqueous solution was proved. The partition behavior of tetracycline hydrochloride in the ethanol/2-propanol–(NH4)2SO4 aqueous two-phase system was investigated by determining partition coefficients and extraction efficiency. The partition coefficient and extraction efficiency of tetracycline hydrochloride in the ethanol–(NH4)2SO4 ATPS could reach 12.51% and 75.77% respectively at pH 2.00 and 0.50 g/mL (NH4)2SO4, furthermore, that of tetracycline hydrochloride in the 2-propanol–(NH4)2SO4 ATPS could reach 30.03% and 87.70% respectively at pH 1.52 and 0.50 g/mL (NH4)2SO4. The target was found to partition preferentially into the alcohol-rich phase in its cation form at pH < 4.0. The effects of the concentration of salt, the type of alcohol, pH and temperature were discussed in detail. The partition of target to the top phase was enhanced by decreasing pH from its isoelectric point of 5.4 and increasing the concentration of salt and temperature. Another objective of this study was to discuss the underlying mechanism governing the uneven partition of target and phase-separation. The experimental phenomenon and results both indicate that the salting-out effect of salt is the driving force for the uneven partition of target, so the salting-out effect of salts on the separation of target cannot be neglected in discussing aqueous two-phase extraction mechanism.Graphical abstractResearch highlights▶ The feasibility of applying the water-miscible alcohol–salt ATPS to separate small molecular antibiotics was proved. ▶ TC·HCl was found to partition preferentially into the top phase in its cation form. ▶ The salting-out effect of salts is the driving force for the formation of ATPS and the uneven partition of target.

Binodal data for the ethanol + K3PO4/K3C6H5O7/Na3C6H5O7 + water systems were experimentally determined at (298.15 and 313.13) K. On the basis of the binodal data fitting equation with the highest accuracy and the Lever rule, the liquid−liquid equilibrium data for the investigated systems at 298.15 K were directly calculated by MATLAB. The Othmer−Tobias equation and Bancroft equation were used to correlate tie-line data and evaluate the reliability of the calculation method and the corresponding tie-line data. The salting-out strength of salt ions was compared by the parameter of effective excluded volume and the binodal curves plotted in molality, while the salting-out strength of salts was compared by the parameter of salting-out coefficient and the binodal curves plotted in mass fraction. The salting-out strength of the investigated salts is in the order K3PO4 > Na3C6H5O7 > K3C6H5O7. As for salt ions, the salting-out strength of anions is in the order PO43− < C6H5O73−, while the salting-out strength of Na+ is similar to K+. The effects of salt, hydrophilic alcohol, and temperature on liquid−liquid equilibria were also discussed. The shapes and locations of binodal curves are not sensitive to the investigated temperature range. The additions of salt and ethanol both increase the tie-line length and the absolute value of the tie-line slope.