Maximum Binding Capacity Research Articles

PH-dependent Release Matrix Oral Formulation of Prussian Blue to Improve its Efficacy as an Internal Decorporation Agent.

Prussian Blue (PB) is available as conventional release dosage form "Radiogardase" with effective daily dose of 3-10 g (very high). The target site is the duodenum, where it inhibits the enterohepatic circulation of Cs & Tl ions, enhancing their fecal excretion. To enhance efficacy, target release, reduce the dose and side effects, oral pH-dependent matrix formulation of PB based on in-situ gelation of sodium alginate along with calcium salts was formulated and evaluated. Different combinations of matrix granules were formulated and optimized. The optimized one was compressed using Polyvinylpyrrolidone K30 (Pvp K30) in different batches and optimized. Langmuir adsorption isotherm was used to assess in-vitro binding efficacy of formulation to thallium using atomic absorption spectroscopy. The proof of concept i.e., drug release in the duodenum was studied through pharmacoscintigraphy using radiolabeled formulation in rabbits. The optimized granules showed no drug release in an acidic medium for 2 h whereas complete empty of the basket in a basic medium within 30-60 minutes. The matrix tablet formulation with Pvp K30 (10% w/w) was optimized with desired hardness and optimum in-vitro release profile. The release data fitted to various linear kinetic models, Hixson-Crowell r2 (0.9906) best fit, confirmed the erosion-based release mechanism. The maximum binding capacity (MBC) was found significantly higher (89.60 mg Tl/g formulation) than that of PB API (65.90 mg Tl /g PB API). Pharmacoscintigraphic images confirmed intact formulation in the stomach up to 2h and burst release in intestine thereafter. The results exemplify oral pH-dependent PB matrix formulation which achieved desirable target release at the duodenum and in-vitro binding efficacy towards Tl ion was appreciable.

Computer assisted preparation and adsorption properties of electrospinning imprinted nanofibers

Dimethyl phthalate (DMP) was used as template molecule to prepare dimethyl phthalate imprinted polymer. The difference of characterization between MINFs and NINFs was analyzed by infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The adsorption performance of imprinted nanofibers was studied through static experiment, isothermal experiment, and selective experiment, respectively. Simultaneously, the nanofibers was applied to analysis for water samples as packing material for solid phase columns. The results of adsorption kinetics showed that MINFs had high sensitivity and selectivity. MINFs showed better binding capacity than NINFs. The maximum binding capacity of MINFs was 4.6×10-2 mmol/g, and that of NINFs was 2.6×10-2 mmol/g. Solid phase extraction (SPE) was used to detect the concentration of DMP in real water samples, the recovery rate reaches 99.45%.

High unbound flucloxacillin fraction in critically ill patients

ObjectivesTo describe the unbound and total flucloxacillin pharmacokinetics in critically ill patients and to define optimal dosing strategies.Patients and methodsObservational multicentre study including a total of 33 adult ICU patients receiving flucloxacillin, given as intermittent or continuous infusion. Pharmacokinetic sampling was performed on two occasions on two different days. Total and unbound flucloxacillin concentrations were measured and analysed using non-linear mixed-effects modelling. Serum albumin was added as covariate on the maximum binding capacity and endogenous creatinine clearance (CLCR) as covariate for renal function. Monte Carlo simulations were performed to predict the unbound flucloxacillin concentrations for different dosing strategies and different categories of endogenous CLCR.ResultsThe measured unbound concentrations ranged from 0.2 to 110 mg/L and the observed unbound fraction varied between 7.0% and 71.7%. An integral two-compartmental linear pharmacokinetic model based on total and unbound concentrations was developed. A dose of 12 g/24 h was sufficient for 99.9% of the population to achieve a concentration of >2.5 mg/L (100% fT>5×MIC, MIC = 0.5 mg/L).ConclusionsCritically ill patients show higher unbound flucloxacillin fractions and concentrations than previously thought. Consequently, the risk of subtherapeutic exposure is low.

Simple fabrication of biocompatible chitosan/graphene oxide microspheres for pH-controlled amoxicillin delivery

Chitosan (CS) is one of the main members of the polysaccharide family which could be used for obtaining a system with a pH-controlled and sustained drug release profile. By considering this, the current research describes the simple fabrication of a series of the new pH-sensitive microspheres based on CS and graphene oxide (GO) to evaluate their efficiency as the drug carrier. The successful formation of the CS/GO microspheres was explored via several characterization techniques. Amoxicillin (AMX) as an antibacterial drug was loaded about 78%-89% in the prepared microspheres (AMX@CS/GO). The highest drug loading value was obtained for CS/GO; 15%. Drug release and MTT tests respectively approved the positive influence of CS in obtaining sustained and pH-controlled AMX release behavior and more biocompatibility. From this isotherm study, the maximum binding capacity of CS/GO 15% for AMX was determined at about 172.41 mg g−1. The antibacterial activity of the AMX loaded microspheres was confirmed via the disc diffusion method. In conclusion, the outputs of this work revealed that the fabricated CS/GO 15% could be potentially proposed as a biocompatible system for drug delivery applications.

A potential method for one-step purification and direct immobilization of target protein in cell lysate with magnetic microbeads

Functional carrier capable of covalently binding proteins from crude lysate under mild condition has become increasingly important in bioprocess. In this paper, a magnetic microbead that can covalently immobilize specific proteins directly from crude protein solution was developed, and its application conditions and stability were evaluated. The SpyCatcher was firstly modified with N-terminal cysteine by genetic methods and then the cys-SpyCatcher was covalently immobilized on epoxy-modified magnetic beads by epoxy-thiol reaction. The reaction between the epoxy and the only terminal thiol group in cys-SpyCatcher ensured the same orientation of the cys-SpyCatcher on the particle surface, while the maximum binding capacity of cys-SpyCatcher reached 23.6 μg/mg under the condition of 250 mM Na2SO4, pH 8.5 at initial cys-SpyCatcher concentration of 3 mg/mL. The functional magnetic microsphere (MS@cys-SpyCatcher) showed covalent site-specific capture property for enhanced green fluorescent protein fused with SpyTag (SpyTag-EGFP). A maximum binding capacity of (25 μg SpyTag-EGFP)/(mg beads) was far more than that of the previous carrier with SpyCatcher. In addition, the MS@cys-SpyCatcher could specifically capture the SpyTagged protein directly from the cell lysate, and this carrier showed good stability at pH 4–9 and temperature of 30–70ºC. Therefore, as a universal covalent capture carrier, it is believed that the MS@cys-SpyCatcher is useful in one-step purification and site-specific immobilization of the SpyTagged protein in bioprocess or biomedical application.

Amidinothiourea‐linked covalent organic framework for the adsorption of heavy metal ions

AbstractFor the first time, a novel amidinothiourea‐linked covalent organic framework (COF) (TpAt) has been successfully synthesized by the condensation between 1,3,5‐triformylphloroglucinol and amidinothiourea via vacuum solvothermal reaction, and was further utilized for the adsorption of metal ions from aqueous solution. The effects of initial concentration, pH and contact time on the adsorption process were investigated. As a result, the TpAt COF showed maximum binding capacities as high as 95.44, 100.76 and 99.08 mg g–1 for Cr(III), Cd(II) and Cu(II) within 180 min at the initial concentration of 100 mg L–1, respectively. The isotherms of metal ions onto TpAt could be described by the Freundlich isotherm equation, and the adsorption kinetics followed the pseudo‐second‐order model. The TpAt could be reused for more than five adsorption–elution cycles, whilst basically maintaining its original adsorption performance and the structural integrity of the COF layers. The robust adsorption efficiency can be attributed to the coordination between metal ions and N, O and S atoms in the TpAt framework. The TpAt COF represents an ideal candidate for the removal of heavy metal ions in environmental pollution treatment. © 2021 Society of Industrial Chemistry.

Development of molecular imprinting-based smart cryogels for selective recognition and separation of serum cytochrome-c as a biochemical indicator

The recognition and detection of proteins has an important role in the fields of biochemistry and medicine in term of diagnosis and prognosis. In this study, molecularly imprinted cryogel (MIP) was synthesized for the selective recognition of Cytochrome-c (Cyt-c) by cryopolymerization techniques with the lanthanide-chelate approach using (MAAP)2-Ce(III) as complex functional monomer and Cyt-c as a template protein. The incorporation of template with monomer was characterized by near- infrared (Near-IR) spectroscopy. The binding capacity was optimized in accordance with numerous experimental parameters including pH, initial Cyt-c concentration, flow rate, temperature and ionic strength. As a result, the maximum binding capacity reached to 98.33 mg g−1 in a buffer system with a pH of 6.0. Beside of the excellent reusability performance of prepared MIP, it was successfully applied to separation of template Cyt-c in the existence of hemoglobin (Hb) and myoglobin (Mb) chosen as interfering proteins. The relative selectivity constants of the Cyt-imprinted polymer were determined as 13.84 for the Cyt/Mb pair and 16.05 for the Cyt/Hb pair. Consequently, a high selectivity, simple and cheap strategy for efficient separation of proteins was provided with this novel MIP cryogel.

Preparation of molecularly imprinted polymer with class-specific recognition for determination of 29 sulfonylurea herbicides in agro-products

Molecularly imprinting polymers with high selectivity toward 29 sulfonylurea herbicides were synthesized by precipitation polymerization, using metsulfuron-methyl and chlorsulfuron as the template molecule, 4-vinylpyridine as the function monomer, divinylbenzene as the crosslinking agent, and acetonitrile as porogen. The imprinted polymers were characterized and measured by scanning electron microscopy (SEM) and equilibrium adsorption experiments. The molecularly imprinted polymers displayed specific recognition for the tested 29 sulfonylurea herbicides, and the maximum apparent binding capacity was found to be 18.81 mg/g. The synthesized polymer was used as a solid-phase extraction (SPE) column coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of the tested analytes in agro-products. Within the range of 2-100 μg/L, the tested analytes have achieved a good linear association with correlation coefficient (R2) > 0.999. The calculated limits of detection (LODs, S/N=3) as along with limits of quantification (LOQs, S/N=10) were in the ranges of 0.005-0.07 μg/L and 0.018-0.23 μg/L, respectively. Under different spiking levels, the recovery rates were ranged from 74.8% - 110.5%, and the relative standard deviation (RSDs) were < 5.3%. Finally, the feasibility of the proposed methodology was successfully applied for detection of sulfonylurea herbicides in crops, vegetables, and oils samples.

Caffeine – treat or trigger? Disparate behavioral and long-term dopaminergic changes in control and schizophrenia-like Wisket rats

The influence of caffeine on behavioral functions in both healthy and schizophrenic subjects is controversial. Here we aimed to reveal the effects of repeated caffeine pre- and post-training treatments on motor and exploratory activities and cognitive functions in a reward-based test (Ambitus) along with a brain region-specific dopamine D2 receptor profile in control and schizophrenia-like WISKET model rats. In the control animals, pre-treatment caused temporary enhancement in motor activity, while permanent improvement in learning function was detected in the WISKET animals. Post-treatment produced significant impairments in both groups. Caffeine caused short-lasting hyperactivity followed by a rebound in the inactive phase determined in undisturbed circumstance. Caffeine treatment substantially enhanced the dopamine D2 receptor mediated G-protein activation in the prefrontal cortex and olfactory bulb of both groups, while it increased in the dorsal striatum and cerebral cortex only in the WISKET animals. Caffeine enhanced the maximal binding capacity in the hippocampus and cerebral cortex of WISKET animals, but it decreased in the prefrontal cortex of the control animals. Regarding the dopamine D2 receptor mRNA expression, caffeine treatment caused significant enhancement in the prefrontal cortex of WISKET animals, while it increased the hippocampal dopamine D2 receptor protein amount in both groups. This study highlights the disparate effects of caffeine pre- versus post-training treatments on behavioral parameters in both control and schizophrenia-like animals and the prolonged changes in the dopaminergic system. It is supposed that the delayed depressive effects of caffeine might be compensated by frequent coffee intake, as observed in schizophrenic patients.

Experimental investigation and mass transfer modelling of 3D printed monolithic cation exchangers

3D printing has recently found application in chromatography as a means to create ordered stationary phases with improved separation efficiency. Currently, 3D printed stationary phases are limited by the lack of 3D printing materials suitable for chromatographic applications, and require a strict compromise in terms of desired resolution, model size and the associated print time. Modelling of mass transfer in 3D printed monoliths is also fundamental to understand and further optimise separation performance of 3D printed stationary phases. In this work, a novel 3D printing material was formulated and employed to fabricate monolithic cation exchangers (CEXs) with carboxyl functionalities. CEXs were printed with ligand densities of 0.7, 1.4, 2.1 and 2.8 mmol/g and used in batch adsorption experiments with lysozyme as model protein. All CEXs demonstrated high binding strength towards lysozyme, with maximum binding capacities of up to 108 mg/mL. The experimental results were described using mass transfer models based on lumped pore diffusion and lumped solid diffusion mechanisms adapted to reflect the complex geometry of the 3D printed monoliths. An exact 3D model as well as less computationally demanding 1D and 2D approximations were evaluated in terms of their quality to capture the experimental trend of batch adsorption kinetic data. Overall, the model results indicate that mass transfer in the fabricated CEXs is mostly controlled by pore diffusion at high protein concentrations in the mobile phase, with solid diffusion becoming important at low protein concentrations. Also, the kinetic data were approximated equally well by both the full 3D model as well as the 2D approximation, indicating leaner mathematical models of lower dimensionality can be employed to describe mass transfer in complex three dimensional geometries. We believe this work will help spur the development of 3D printable materials for separations and aid in the development of quantitative platforms to evaluate and optimise the performance of 3D printed monoliths.

Pyometra-associated insulin resistance assessment by insulin binding assay and tyrosine kinase activity evaluation in canine muscle tissue

Diestrus is associated with insulin resistance in bitches and pyometra can further impair insulin sensitivity. This study aimed to compare insulin sensitivity, insulin binding, and tyrosine kinase activity in bitches in anestrus, diestrus, or with pyometra. Patients submitted to elective ovariohysterectomy were divided into anestrus (n = 11) or diestrus (n = 13) according to reproductive history, vaginal cytology, and uterine histology. The group pyometra (n = 8) included bitches diagnosed with the disease based on clinical presentation and abdominal ultrasound findings and further confirmed by uterine histopathology. All patients were submitted to an intravenous glucose tolerance test (IVGTT) before ovariohysterectomy, and rectus abdominis muscle samples were collected during surgery for plasmatic membrane suspension preparation. Muscle-membranes were submitted to cold saturation insulin binding assay for dissociation constant (Kd) and maximum binding capacity (Bmax) determination, as well as exogenous substrate Poly (Glu: Tyr 4:1) phosphorylation assay for basal tyrosine kinase evaluation. Bitches with pyometra showed higher basal insulin (P < 0.001) and higher area under the curve (AUC) for insulin (P = 0.01) and glucose (P < 0.001) response during the IVGTT in comparison with bitches in anestrus or diestrus. Diestrus (P < 0.0001) and pyometra (P = 0.001) were associated with reduced tyrosine kinase activity in comparison with anestrus. No differences were documented in Kd and Bmax results for the low-affinity/high-capacity insulin receptors; however, high-affinity/low-capacity insulin receptors showed higher Kd and Bmax results in bitches in diestrus or with pyometra (P < 0.05) in comparison with anestrus. Despite the pyometra group showed the highest Kd values (P < 0.01), its Bmax results did not differ from the diestrus group (P > 0.05). Diestrus’ higher Kd values and reduced tyrosine kinase activity in muscle tissue were compensated by increased total insulin binding capacity. Absent differences in IVGTT results between diestrus and anestrus bitches corroborate this finding. However, in bitches with pyometra, the highest Kd values were not compensated by increased total insulin binding capacity. This finding was associated with insulin resistance and glucose intolerance in IVGTT results. Moreover, pyometra resolution restored insulin sensitivity and glucose tolerance. These features can play a key role in pyometra-associated CDM, as well as in diabetic remission after pyometra resolution.

A hollow visible-light-responsive surface molecularly imprinted polymer for the detection of chlorpyrifos in vegetables and fruits

A visible-light-responsive azobenzene derivative, 3,5-dichloro-4-((2,6-dichloro-4-(methacryloyloxy)phenyl)diazenyl)benzoic acid, was synthesized and used as the functional monomer to fabricate a visible-light-responsive core-shell structured surface molecularly imprinted polymer (PS-co-PMAA@VSMIP). After removal of the sacrificial PS-co-PMAA core, a hollow structured surface molecularly imprinted polymer (HVSMIP) was obtained. Both the PS-co-PMAA@VSMIP and HVSMIP were used for the detection of chlorpyrifos, a moderately toxic organophosphate pesticide. They exhibited good visible-light-responsive properties (550 nm for trans→cis and 440 nm for cis→trans isomerization for an azobenzene chromophore) in ethanol/water (9:1, v/v). Compared with the PS-co-PMAA@VSMIP, the HVSMIP had a larger surface area, pore volume, binding capacity, imprinting effect, maximum chemical binding capacity, dissociation constant, and photo-isomerization rate. The HVSMIP was applied to detect trace chlorpyrifos in fruit and vegetable samples. This was achieved by measuring the trans→cis rate constant of the HVSMIP in the sample solution, with good recoveries, low relative standard deviations, and a low detection limit.

Nonwoven Ion-Exchange Membranes with High Protein Binding Capacity for Bioseparations.

This study presents the preparation and characterization of UV-grafted polybutylene terepthalate (PBT) ion exchange nonwoven membranes for chromatographic purification of biomolecules. The PBT nonwoven was functionalized with sulfonate and secondary amine for cation and anion exchange (CEX and AEX), respectively. The anion exchange membrane showed an equilibrium static binding capacity of 1300 mg BSA/g of membrane, while the cationic membranes achieved a maximum equilibrium binding capacity of over 700 mg hIgG/g of membrane. The CEX and AEX membranes resulted in dynamic binding capacities under flow conditions, with a residence time of 0.1 min, of 200 mg hIgG/mL of membrane and 55 mg BSA/mL of membrane, respectively. The selectivity of the PBT-CEX membranes was demonstrated by purifying antibodies and antibody fragments (hIgG and scFv) from CHO cell culture supernatants in a bind-an-elute mode. The purity of the eluted samples exceeded 97%, with good log removal values (LRV) for both host cell proteins (HCPs) and DNA. The PBT-AEX nonwoven membranes exhibited a DNA LRV of 2.6 from hIgG solutions in a flow-through mode with little loss of product. These results indicate that these membranes have significant potential for use in downstream purification of biologics.

Activity, stability, and binding capacity of β-galactosidase immobilized on electrospun nylon-6 fiber membrane

In this research, we explored various immobilized enzyme support materials, including the novel nylon-6 fiber membrane (NFM), and evaluated the increase in surface area and its effect on enzyme binding potential. We also manipulated incubation and reaction conditions and assessed the subsequent effects on activity and stability of β-galactosidase, with comparisons between various solid support materials and free (dissolved) enzyme. Nylon-6 fiber membranes were created by electrospinning and were compared with other materials as solid supports for enzyme binding. The other materials included polyvinylidene fluoride 5-kDa nanofiltration dairy membranes, nylon-6 pellets, and silica glass beads. Scanning electron microscopy revealed the large surface area of NFM, which correlated with greater enzyme activity compared with the relatively flatter surfaces of the other solid support materials. Enzyme activity was measured spectrophotometrically with the color-changing substrate o-nitrophenyl-β-d-galactopyranoside. Compared with the other solid supports, NFM had greater maximum enzyme binding potential. Across pH conditions ranging from 3.5 to 6.0 (including the optimal pH of 4.0-5.0), enzyme activity was maintained on the membrane-immobilized samples, whereas free enzyme did not maintain activity. Altering the storage temperature (4, 22, and 50°C) affected enzyme stability (i.e., the ability of the enzyme to maintain activity over time) of free and polyvinylidene fluoride membrane samples. However, NFM samples maintained stability across the varying storage temperatures. Increasing the immobilization solution enzyme concentration above the maximum enzyme binding capacity had no significant effect on enzyme stability for membrane-immobilized samples; however, both had lower mean stability than free enzyme by approximately 74%. With further development, β-galactosidase immobilized on NFM or other membranes could be used in continuous processing in the dairy industry for a combination of filtration and lactose hydrolysis-creating products that are reduced in lactose and increased in sweetness, with no requirement for "added sugars" on the nutrition label and no enzyme listed as final product ingredient.

Utilization of extracellular fungal melanin as an eco-friendly biosorbent for treatment of metal-contaminated effluents

Fungal melanins have been considered as potential biosorbents due to their metal-binding properties, stability, and scalability. Previous studies established scalable fungal melanin production methods with promising strains, however, their applicability for metal-contaminated effluents treatment has not been sufficiently reported. Herein, melanin pigment derived from Amorphotheca resinae was produced and characterized using microscopy and spectroscopy techniques. Adsorptive properties towards Cu(II), Pb(II), Cd(II), and Zn(II) were evaluated using batch tests. Melanin pigment was composed of aggregates of nanosized particles with indole-based constituents. Adsorption capacities increased with the pH of solution, especially at pH > 4.0. Maximum binding capacities of Cu(II), Pb(II), Cd(II), and Zn(II) on melanin were 69.18, 103.23, 24.31, and 13.57 mg/g, respectively. The competitive adsorption experiments elucidated affinity as Cu(II)>Pb(II)≫Cd(II)>Zn(II). Adsorption time generally required <2.5 h to reach equilibrium; the pseudo-second-order kinetic model well described the kinetics. Chelating ability of free radicals in pigment was considered as a possible mechanism for adsorption. Initial adsorption capacities remained almost intact even after 5 consecutive adsorption–desorption cycles. Complete removal of Cu(II), Pb(II), and Cd(II) from metal-contaminated effluent was confirmed. Consequently, melanin pigment derived from A. resinae can be used as a biosorbent suitable for the treatment of metal-contaminated aqueous solutions.

Selective Recognition and Separation of Ubiquitin by Nanoparticle Embedded Cryogel Traps with Ubiquitin Memories Based on Photosensitive Covalent Imprinting

Recognition and determination of ubiquitin (Ubq) is very important since it affects the enzymatic mechanisms, which causes damages in the living organisms. This can lead to diseases especially in neuronal system. Molecularly imprinted polymers (MIPs) are selective resins that exhibit high affinity toward target compounds. MIPs have attracted significicant research interest because of their various applications in solid phase extraction, biosensors and drug delivery, etc. Various MIP types can be used such as thermo-sensitive, pH-sensitive, biomolecule-sensitive, ion-sensitive and photo-sensitive in these applications. Photosensitive MIPs can be used to increase the selectivity and binding efficiency to decrease denaturation of target biomolecules. The aim of this study is to prepare photosensitive cross-linked p(Ubq-co-MACys-Ru(bipyr)2-MACys) polymeric nanoparticles (UbqINPs) and leach with 0.5 M HCl to create Ubq memories onto nanoparticles (UbqINPs) and optimize their binding parameters in cryogel based column system. For this purpose, different factors such as pH, flow rate, ionic strength and temperature were investigated, and maximum ubiquitin binding capacity was found to be 25 mg/g at pH 7. The results showed that the UbqINPs can be considered as a good binding material for recognition and separation of Ubq.

Molecularly imprinted polymer embedded-cryogels as selective genotoxic impurity scavengers

ABSTRACT This research aims to design, preparation, and characterization of molecularly imprinted polymeric particles embedded-cryogels for the selective removal of potentially genotoxic impurities 2-aminopyridine and 5-amino-2-chloropyridine in model active pharmaceutical ingredients piroxicam and tenoxicam. For this purpose, aminopyridines imprinted poly (hydroxyethyl methacrylate-methacryloylamido benzotriazole-Cu(II)) particles were prepared and embedded into the cryogel structure. The characterization of the prepared composite cryogels was carried out by FT-IR, swelling tests, and SEM analyses. The results confirmed that the target aminopyridines binding increased with increasing initial concentration up to 1.5 mg mL−1 which is a saturation point. The highest binding of potentially genotoxic impurities was obtained at pH 7.0 and the maximum binding capacity values of the prepared cryogels for 2-aminopyridine and 5-amino-2-chloropyridine were achieved as 93.2 mg g−1 and 81.1 mg g−1, respectively. The imprinted particles embedded-cryogels displayed great affinity toward the target aminopyridines in model active pharmaceutical ingredients piroxicam and tenoxicam. The reusability studies confirmed that the prepared molecularly imprinted particles embedded-cryogels can be successfully reused without a considerable reduce in the binding of target potentially genotoxic impurities to the cryogels after 10 binding-desorption cycles.

Spectroscopic Analysis of Fe Ion-Induced Fluorescence Quenching of the Green Fluorescent Protein ZsGreen.

The fluorescence of fluorescent proteins (FPs) is quenched when they are exposed to certain transition metals, which makes them promising receptor materials for metal biosensors. In this study, we report the spectroscopic analysis of metal-induced fluorescence quenching of the fluorescent protein ZsGreen from Zoanthus sp. The fluorescence of ZsGreen was reduced to 2%, 1%, and 20% of its original intensity by Fe2+, Fe3+, and Cu2+, respectively. Metal titration experiments indicated that the dissociation constants of Fe2+, Fe3+, and Cu2+ for ZsGreen were 11.5, 16.3, and 68.2μM, respectively. The maximum binding capacities of ZsGreen for Fe2+, Fe3+, and Cu2+ were 103.3, 102.2, and 82.9, respectively. Reversibility experiments indicated that the fluorescence of ZsGreen, quenched by Fe2+ and Fe3+, could be recovered, but only to about 15% of its original intensity, even at a 50-fold molar excess of EDTA. In contrast, the fluorescence quenched by Cu2+ could be recovered up to 89.47% of its original intensity at a Cu2+: EDTA ratio of 1:5. The homology model of ZsGreen revealed that the protein does not share any metal-binding sites with previously reported FPs, suggesting that ZsGreen contains unprecedented binding sites for fluorescence quenching metal ions.

Eco-friendly ionic liquid imprinted polymer based on a green synthesis strategy for highly selective adsorption tylosin in animal muscle samples.

A novel eco-friendly molecularly imprinted polymer (MIP) was proposed as solid-phase extraction (SPE) adsorbent to selective adsorption tylosin (TYL) in animal muscle samples. The MIP was synthesized in aqueous by using 1,4-butanediyl-3,3-bis-1-vinyl imidazolium chloride and 2-acrylamide-2-methylpropanesulfonic acid as bifunctional monomer. The obtained MIP had excellent selectivity towards TYL in water, and the maximum binding capacity can reach 123.45mgg-1. Combined with high-performance liquid chromatography, the presented MIP can be used as SPE sorbent to recognize and detect TYL in the range of 0.008 to 0.6mgL-1 (R2 = 0.9995). The limit of detection and limit of quantification were 0.003mgL-1 and 0.008mgL-1, and the intraday and interday precision were 1.05% and 3.36%, respectively. Under the optimal condition, the established MIP-SPE-HPLC method was successfully applied to separate and determine trace TYL in chicken, pork, and beef samples with satisfactory recoveries ranged from 94.0 to 106.3%, and the MIP-SPE cartridge can be cycled at least 20 times. This study implies a promising green MIP-SPE-HPLC method for highly selective adsorption and analysis trace TYL in complex matrices.

Molecularly imprinted spongy columns for Angiotensin(II) recognition from human serum.

Angiotensin II (AngII), the effector peptide of the renin angiotensin system and has an important role in regulating cardiovascular hemodynamics and structure. AngII is an important biomarker for certain diseases that are associated with cardiovascular disorders, i.e., influenza, SARS‐CoV‐2, tumors, hypertension, etc. However, AngII presents in blood in very low concentrations and they are not stable due to their reactivity, therefore spontaneous detection of AngII is a big challenge. In this study, AngII‐imprinted spongy columns (AngII‐misc) synthesized for AngII detection from human serum, and characterized by surface area measurements (BET), swelling tests, scanning electron microscopy (SEM), FTIR studies. AngII binding studies were achieved from aqueous environment and maximum binding capacity was found as 0.667 mg/g. It was calculated that the AngII‐miscs recognized AngII 8.27 and 14.25 times more selectively than competitor Angiotensin I and Vasopressin molecules. Newly produced AngII‐misc binds 60.5 pg/g AngII from crude human serum selectively. It has a great potential for spontaneous detection of AngII from human serum for direct and critical measurements in serious diseases, that is, heart attacks, SARS‐CoV‐2, etc.