High-Sensitivity Creatinine Detection via a Dual-Emission Ratiometric Fluorescence Probe Incorporating Amino-MIL-53@Mo/ZIF-8 and Rhodamine B

Quantifying creatinine (Cn) in biological fluids is crucial for clinically assessing renal insufficiency, thyroid irregularities, and muscle damage. Therefore, it is crucial for human health to have a simple, quick, and accurate Cn analysis technique. In this study, we have successfully synthesized a 3D ratiometric dual-metal-organic framework, namely, the amino-MIL-53@Mo/ZIF-8 and rhodamie B heterostructure, using an internal strategy for sustained growth. The dual-MOF functions as an adsorbent and preconcentrates Cn. The pH, reaction time, and volume ratio of amino-MIL-53@Mo/ZIF-8/rhodamie B were optimized using the one-variable-at-a-time technique in this study. The quantitative study of the Cn concentration for this RF biosensor was obtained under ideal conditions (R2 = 0.9962, n = 3), encompassing the linear range of 0.35-11.1 μM. The detection and quantitation limits were 0.18 and 0.54 nM, respectively. Both intra- and interday reproducibility showed high repeatability of the RF biosensor, UV-vis, and ZETA potential studies, and the Stern-Volmer relationship was used to clarify the fluorescence quenching process. These superior sensing capabilities and the benefits of simple manufacturing, acceptable stability, and practicality make the RF biosensor intriguing for ultrasensitive Cn detection in practical applications.

Paper-based microfluidic system and chiroptical functionalized gold nano-oval for colorimetric detection of L-Tryptophan

"The development and deployment of a practical and portable technology for on-site chiral identification of enantiomers hold immense significance in the fields of medical and biological sciences. Among the essential amino acids, Tryptophan (Trp) plays a crucial role in human metabolism and serves as a diagnostic marker for various metabolic disorders. In this study, we introduce an innovative approach that combines an enantio-selective ZIF-8-His MOF-MIPs packed-bed centrifugal microfluidic system with an enantioselective colorimetric sensor probe. This system is further integrated with smartphone-based on-site data recording. The basis of this colorimetric sensor's operation lies in the controlled morphology and surface passivation of gold nano-ovals (Au-NOs) through DL-Alanine. To confirm the successful synthesis of the chiral recognition elements, we employed various characterization techniques, including FE-SEM, TEM, FTIR, CD, UV-Vis, zeta potential, DLS, and XRD. Our focus was on optimizing operational parameters for the effective separation and determination of L-chiral tryptophan on-site. The sensor exhibited two linear ranges for L-Trp detection: 0-5.42 and 5.42-80.47 mM, with a detection limit of 0.5 mM. The integrated system possesses advantages such as ease of availability, preparation, high stability, desirable selectivity even in the presence of similar biomolecules, and rapid detection capabilities. Furthermore, our method demonstrated successful enantioselective sensing of L-Trp in various biological samples, including human blood plasma, urine, milk, and bovine serum albumin (BSA), yielding promising results. The integrated microfluidic platform follows a "sample-in and answer-out" approach, making it highly applicable in healthcare, environmental monitoring, food safety analysis, and point-of-care testing. The chiral recognition pretreatment assay and self-contained, automated colorimetric detection on the microfluidic disc represent a promising avenue for cutting-edge research in these domains".

Microfluidic chip and chiroptical gold nanoparticle-based colorimetric sensor for enantioselective detection of L-tryptophan

Herein, we introduce a novel integrated system that merges an enantio-discriminative bio-MOF-packed centrifugal microfluidic chip made from PDMS with a user-friendly on-site colorimetric sensor. This innovative approach enables the precise enantioselective recognition of L-tryptophane (L-Trp). This chiral recognition probe was successfully synthesized through meticulous control of nano-ovals-shaped gold nanoparticles morphology and surface passivation. The operational factor of this methodology was optimized to ensure simplicity, practicality, and efficiency. This optimization led to reduced reagent consumption and instantaneous analytical feedback. The integrated system was effectively applied for enantioselective separation and quantification of L-Trp across an extensive linear range of 50 μM-1.5 mM, impressive limit of detection as low as 15 μM. It is noteworthy that this integrated system demonstrated desirable selectivity even in the presence of similar biomolecules, showcasing its robust performance and rapid detection capability. Further extended the application of this strategy to exceptional performance across enantioselective sensing of L-Trp in various sample matrices, comprising bovine serum albumin, bovine milk, blood plasma and urine samples. This integrated microfluidic sample pretreatment, chiroptical sensing, and on-site signal recording with a smartphone hold tremendous potential for widespread implementation, practical applications engaging healthcare and environmental, food safety, and point-of-needs analysis, facilitating successive solution mixing and colorimetric detection.

Enhancing On-Skin Analysis: A Microfluidic Device and Smartphone Imaging Module for Real-Time Quantitative Detection of Multianalytes in Sweat

Wearable sweat sensors present exciting opportunities for advancing personal health monitoring and noninvasive biomarker measurements. However, existing sensors often fall short in accurate detection of low analyte volumes and concentrations and lack multimodal sensing capabilities. Herein, we present a highly portable four-channel microfluidic device capable of conducting simultaneous sweat sampling and fluorometric sensing of potential biomarkers, such as l-Tyr, l-Trp, Crt, and NH4+, specifically designed for kidney disease monitoring. Our microfluidic device seamlessly integrates with smartphones, facilitating easy data retrieval and analysis. The core of the sensing array is a novel fluorometric solid-state mechanism utilizing carbon polymer dots derived from dopamine, catechol, and o-phenylenediamine monomers embedded in gelatin hydrogels. The sensors exhibit exceptional performance, offering linear ranges of 5-275, 6-170, 4-220, and 5-170 μM, with impressively low detection limits of 1.5, 1.2, 1.3, and 1.4 μM for l-Tyr, l-Trp, Crt, and NH4+, respectively. Through meticulous optimization of operational variables, comprising the temperature, sample volume, and assay time, we achieved the best performance of the device. Furthermore, the sensors exhibited remarkable selectivity, effectively distinguishing between biologically similar species and other potential biological compounds found in sweat. Our evaluation also extended to monitoring kidney diseases in patients and healthy individuals, showcasing the device's utility in world scenarios. Promising results showcase the potential of low-cost, multidiagnostic microfluidic sensor arrays, especially with synthetic skin integration, for enhanced disease detection and healthcare outcomes.

Red-emissive carbon nanostructure-anchored molecularly imprinted Er-BTC MOF: a biosensor for visual anthrax monitoring

Investigating effective fluorescence strategies for real-time monitoring of dipicolinic acid (DPA) is of paramount importance in safeguarding human health. Herein, we present the design of a desirable red-emissive carbon nanostructure anchoring a molecularly imprinted Er-BTC MOF as a fluorescence biosensor for the visual determination of DPA. DPA is a biomarker of Bacillus anthracis, a subcategory of serious infectious diseases and bioweapons. We introduce a paper test strip sensitized with the aforementioned nanostructure, which is integrated with online UV excitation and smartphone digital imaging, resulting in a DPA signal-off sensing platform. The proposed fluorometric visual paper-based biosensor demonstrates wide linear ranges for DPA (10-125 μM) with a LOQ and LOD of 4.32 and 1.28 μM, respectively. The designed platform exhibits impressive emission properties and adaptable surface functional groups, which confirm its desirable selective sensing capabilities against other biological molecules and DPA isomers. As a proof of concept, DPA monitoring is successfully applied to real samples of tap water and urine. This integrated selective paper-based nano-biosensor, coupled with smartphone signal recording, holds great promise for state-of-the-art practical applications including fluorometric/colorimetric detection in healthcare and environmental monitoring, food safety analysis, and point-of-care testing.

Ruthenium-Encapsulated Porphyrinic Organic Polymer as a Photoresponsive Oxidoreductase Mimetic Nanozyme for Colorimetric Sensing

The advantages of porosity and stable unpaired electrons of porphyrinic organic polymers (POPs) with free radicals are exclusive and potentially practical functionalities and combining the semiconductor-like characteristics of these materials and metal ions has been an effective way to assemble an efficient photocatalytic system. Herein, a new ruthenium (Ru) ion-encapsulated porphyrinic organic polymer (POP/Ru) is facilely synthesized as a proper photoresponsive nanozyme with unique photo-oxidase properties. Surprisingly, the proposed POP/Ru revealed outstanding photoresponsive oxidase-mimicking activity due to the synergetic effect of the integration of Ru and π-electrons of POP, which boosts charge separation and transport. POP/Ru was applied to the oxidation of o-phenylenediamine (o-PDA) as a chromogenic probe for producing a colorimetric signal. The kinetic study reveals that these photo-oxidase mimics have a significant affinity for the o-PDA chromogenic agent owing to a lower K_m and superior V_max. Further findings demonstrate that the presence of the l-arginine (l-Arg) target causes an inhibition effect on the photo-nanozymatic colorimetry of POP/Ru. This research develops the applications of the comprehensive colorimetric strategy for ultrasensitive l-Arg monitoring with a limit of detection (LOD) of 15.2 nM in the dynamic range of 4.0 nM-340 μM and illuminates that the proposed photo-oxidase nanozyme as a visual strategy is feasible in l-Arg environmentally friendly colorimetric detection in juice samples.

Synthesis of an IRMOF-1@SiO2 Core-Shell and Amino-Functionalization with APTES for the Adsorption of Urea and Creatinine Using a Fixed-Bed Column Study

Kidney dysfunction is a clinical disease that disables the kidneys to remove the waste products and uremic toxins from the circulation and may lead to fatal kidney failure. Hemodialysis is advantageous in this circumstance since it prevents the accumulation of waste products in the body and facilitates the removal of uremic toxins. However, hemodialysis cannot entirely remove some uremic toxins, such as urea and creatinine. In this paper, a high-performance fixed-bed column for urea and creatinine removal was offered. As a result, a MOF layer was built on SiO₂, which was then amino-functionalized using APTES. Numerous assays were used to characterize the final adsorbent. The adsorption of urea and creatinine was evaluated in batch and continuous conditions. Thus, it was demonstrated that the adsorption behavior of A(0.2)-IRMOF-1@SiO₂ followed the Langmuir isotherm, and it exhibited the maximum adsorption capacity. The batch experiment determined that urea and creatinine had an adsorption capacity of 1325.73 and 625.00 mg·g^-1, respectively. The adsorption capacity was increased, which was due to the presence of amino groups (APTES) on the MOF surface. The continuous operation was evaluated using the A(0.2)-IRMOF-1@SiO₂ fixed-bed column. Thomas and Nelson's models were examined to achieve a better understanding of the adsorption behaviors. The A(0.2)-IRMOF-1@SiO₂ fixed-bed column successfully removed 92.57% of urea and 80.47% of creatinine. The separation factor for urea in comparison to creatinine was 2.40 in the A(0.2)-IRMOF-1@SiO₂ fixed-bed column.

Photo-responsive oxidase-like nanozyme based on a vanadium-docked porphyrinic covalent organic framework for colorimetric L-Arginine sensing

This study reports the development of a vanadium-docked porphyrinic covalent organic framework as a novel class of highly polar photoactive materials. Thanks to its extended π-electron conjugation and high chemical stabilities, this framework can serve as an oxidase-Like photo-nanozyme for photocatalytic oxidation of o-phenylenediamine (o-PDA) and a colorimetric substrate for the production of the yellow-colored oxidized o-PDA (o-PDAox). The physicochemical properties of the as-prepared photo-nanozyme were characterized by several analytical techniques. Its enhanced light harvesting and charge separation and transfer were also verified by electrochemical and spectroscopic analysis. This photo-nonenzymatic colorimetric assay was applied for the sensitive L-Arginine (L-Arg) detection as a typical amino acid in the linear range of 8.1 nM-330 μM with a limit of detection (LOD) of 3.5 nM. The findings of this research confirmed the safety and feasibility of the proposed photo-nonenzymatic colorimetric sensing strategy for the detection of L-Arg and other similar biomolecules in food samples. Kinetic investigation revealed that the photo-responsive oxidase mimic exhibits satisfactory K_m (0.47 mM) and V_max (42.0 μM/s) values. This work broadened our insight into the development of modified porphyrinic-COF-based visible light-responsive oxidase-like photo-nanozyme for environmentally friendly colorimetric biosensing.

Intrinsic Dual-Emitting Carbon Quantum-Dot-Based Selective Ratiometric Fluorescent Mercaptopurine Detection

Mercaptopurine (6-MP), an immunosuppressive drug, has been widely prescribed for treating leukemia and autoimmune diseases. The level of the 6-MP drug in body fluids is of great interest due to the severe health problems related to its overdose. This study used a facile microwave preparation route to synthesize carbon quantum dots (CQDs) using glutathione and formamide as carbon sources. The obtained monodispersed quantum dots showed dual fluorescence emission with a sensitive affinity toward the 6-MP drug. The sensor's response was optimized by tuning the temperature, pH, and volume ratio of the probe. The prepared ratiometric fluorescence method showed accurate measurements for determining mercaptopurine in aqueous solutions in the concentration range of 1.4-7.6 mg L^-1 with the limit of detection of 1.3 mg L^-1. The sensor's performance was assessed in complex solutions, human urine, and human plasma sample and recovery values in the range of 88-127% were obtained. The reliable dual fluorometric sensor showed promising results for 6-MP determination and potential application for the determination of other chemical and biochemical species.

Synthesis of NMOF-5 Using Microwave and Coating with Chitosan: A Smart Biocompatible pH-Responsive Nanocarrier for 6-Mercaptopurine Release on MCF-7 Cell Lines

Cancer is one of the most difficult diseases to treat, threatening the lives of millions of people today. So far, various methods have been used to treat cancer, each having its drawbacks. One of these methods is treatment with anticancer drugs, which unfortunately have severe side effects. One of the causes of these complications is the nonspecific effects of anticancer drugs, which attack normal cells in addition to cancer cells and damage healthy tissues. In this study, we are trying to reduce the side effects and increase the efficacy of the drug by providing smart drug delivery. The metal-organic framework (MOF) was rapidly synthesized using a microwave method and at the nanoscale. The particle size of NMOF-5 was 18-20 nm, and its surface area was 2690 m²·g^-1. A chitosan polymer coating was formed on the nanocarrier after 6-mercaptopurine was introduced. The biocompatible nanocarrier exhibited a high capacity to adsorb the drug. The biocompatible nanocarrier slowly and uniformly released 96.78% of the drug in a simulated solution at pH 5 and 20.52% at pH 7.4. This showed that CS-6-MP-NMOF-5 released the drug smartly and pH-sensitively. The stability of the biocompatible nanocarrier was studied at different pH values and remained stable at pH 5 for up to 48 h. The toxicity study of the MCF-7 cell line at different concentrations for 24 h showed the excellent performance of the biocompatible nanocarrier compared to the free drug in terms of toxicity to breast cancer cells.

Design of a Ratiometric Plasmonic Biosensor for Herceptin Detection in HER2-Positive Breast Cancer

Breast cancer is the most common cause of cancer death in women; therefore, its early detection and treatment are crucial. To achieve this goal, we designed an optical sensor based on direct interaction of trastuzumab [Herceptin (HER)], a monoclonal antibody used to treat HER2-positive breast cancer, with plasmonic nanoparticles. Surface-modified gold nanoparticles (AuNPs) have gained considerable attention in biosensing techniques over the last years, which actuated these nanoparticles to the heart of various biosensing notions. We have exploited the localized surface plasmon resonance (LSPR) of gold nanoparticles to determine HER in human serum. AuNPs were decorated with negatively charged citrate ions, yielding enhanced direct-surface interaction with HER antibodies. The AuNPs are mixed with silver nanoparticles (AgNPs) in an optimized ratio to increase selectivity and sensitivity further. AuNPs detect the HER antibodies using LSPR, whereas AgNPs help monitor interferences' effect on the sensing media. The three effective factors in HER sensing, including the nanoparticle ratio, temperature, and pH were optimized via response surface methodology (RSM) based on the central composite design (CCD). The sensor's response toward HER was achieved in the linear range of 0.5 × 10^-7 to 40 × 10^-7 M with the detection limit of 3.7 × 10^-9 M and relative standard deviation (RSD) less than 5%. The selectivity of the LSPR sensor was assessed by monitoring its response toward HER in the presence of other biological molecules with similar physicochemical properties. Rapid response time (less than 1 min), selectivity, and the simplicity of the developed LSPR-based sensor are the key advantages of the developed sensor.

Low molecular weight chitosan-cyanocobalamin nanoparticles for controlled delivery of ciprofloxacin: Preparation and evaluation

This study was carried out to project a safe nano-drug carrier composed of chitosan and cyanocobalamin (CNCbl) to improve oral delivery of ciprofloxacin hydrochloride (CIP). CIP is classified in class IV of the biopharmaceutical classification system with low solubility and permeabilityA, so it has some problems if given orally. Novel conjugate of low molecular weight chitosan, as a natural biopolymer, and CNCbl was synthesized, and then drug loading and in-vitro drug release were assessed. The loading of CIP was optimized by the Design-Expert software and the central composite design method, and that the optimal drug loading efficiency (57%) was obtained via analysis of variance (ANOVA). In-vitro drug release studies showed controlled release patterns in two various conditions, namely phosphate buffer saline (pH = 7.4) and 0.1 N HCl. Functionalized nano-drug-loaded carrier showed cytotoxicity as much as that of free drug, particle size less than 100 nm as well as positive zeta potential. Due to the beneficial properties of the chitosan-based drug carrier and the suitable features of the CIP-loaded carrier, this chitosan-based nano-drug delivery system can be regarded as an ideal candidate for oral delivery of the CIP as a drug model.

A novel hybrid fluorescence probe sensor based on metal-organic framework@carbon quantum dots for the highly selective detection of 6-mercaptopurine

In the present study, MIL-101(Fe) and amine-carbon quantum dots (CQDs) were combined via a post-synthetic modification (PSM) method; thus, a novel MIL-101(Fe)@amine-CQD hybrid fluorescent probe sensor for the detection of 6-mercaptopurine (6-MP) was synthesized. Amine-CQDs as a fluorescent material can convert the bonding interaction between MIL-101(Fe) and 6-MP into recognizable fluorescence signals, and MIL-101 (Fe) as an adsorbent can pre-concentrate 6-MP. Hereupon, this new sensor demonstrates high selectivity and sensitivity towards the detection of 6-MP. The addition of 6-MP to this probe quenches the fluorescence signal at 599 nm. In this study, factors such as pH, response time, and concentration of MIL-101(Fe)@amine-CQDs were optimized by the one-factor-at-a-time (OFAT) method. Under optimal conditions, the relationship between the fluorescence enhancement factor and the concentration of 6-MP for this sensor in the range of 0.1667-1.0000 μg L^-1 was linear (R² = 0.9977, n = 3). The limit of detection and limit of quantitation were 55.70 ng L^-1 and 202.06 ng L^-1, respectively, which are better than similar techniques. The repeatability of intra-day and inter-day was 2.4% and 4.7%, respectively. This fluorescent sensor was employed to determine 6-MP in real samples and exhibited acceptable results.

A Facile Colorimetric and Spectrophotometric Method for Sensitive Determination of Metformin in Human Serum Based on Citrate-Capped Gold Nanoparticles: Central Composite Design Optimization

For the determination of Metformin in human serum, a facile colorimetric and spectrophotometric sensor was designed based on citrate-capped gold nanoparticles (citrate-GNPs). In this probe, the addition of Metformin to GNP solution generates a naked-eye color change resulting from the aggregation of GNPs. Study of this color conversion and quantity analysis of analyte is operated by spectrophotometric instruments. The three factors pH, time, and GNP ratio were selected to examine their effects on sensing results and their values optimization. The optimization of parameters was done by means of central composite design and one-at-a-time methods. The sensing results proved the highly selective and sensitive performance of the sensor for Metformin in a linear range of 6.25-133.3 ppm with a detection limit of 1.79 ppm. The relative standard deviation (RSD) of the reported method is 2.53%.

Flow injection analysis-flame atomic absorption spectrometry system for indirect determination of sulfite after on-line reduction of solid-phase manganese (IV) dioxide reactor

A new and simple flow injection method followed by atomic absorption spectrometry was developed for indirect determination of sulfite. The proposed method is based on the oxidation of sulfite to sulphate ion using solid-phase manganese dioxide (30% W/W suspended on silica gel beads) reactor. MnO₂ will be reduced to Mn(II) by sample injection in to the column under acidic carrier stream of HNO₃ (pH 2) with flow rate of 3.5mLmin^-1 at room temperature. Absorption measurement of Mn(II) which is proportional to the concentration of sulfite in the sample was carried out by atomic absorption spectrometry. The calibration curve was linear up to 25mgL^-1 with a detection limit (DL) of 0.08mgL^-1 for 400µL injection sample volume. The presented method is efficient toward sulfite determination in sugar and water samples with a relative standard deviation (RSD) less than 1.2% and a sampling rate of about 60h^-1.

Highly efficient ultrasonic-assisted removal of Hg(II) ions on graphene oxide modified with 2-pyridinecarboxaldehyde thiosemicarbazone: Adsorption isotherms and kinetics studies

A novel adsorbent, based on modifying graphene oxide (GO) chemically with 2-pyridinecarboxaldehyde thiosemicarbazone (2-PTSC) as ligand, was designed by facile process for removal of Hg(II) from aqueous solution. Characterization of the adsorbent was performed using various techniques, such as FT-IR, XRD, XPS, SEM and AFM analysis. The adsorption capacity was affected by variables such as adsorbent dosage, pH solution, Hg(2+) initial concentration and sonicating time. These variables were optimized by rotatable central composite design (CCD) under response surface methodology (RSM). The predictive model for Hg(II) adsorption was constructed and applied to find the best conditions at which the responses were maximized. In this conditions, the adsorption capacity of this adsorbent for Hg(2+) ions was calculated to be 309mgg(-1) that was higher than that of GO. Appling the ultrasound power combined with adsorption method was very efficient in shortening the removal time of Hg(2+) ions by enhancing the dispersion of adsorbent and metal ions in solution and effective interactions among them. The adsorption process was well described by second-order kinetic and Langmuir isotherm model in which the maximum adsorption capacity (Qm) was found to be 555mgg(-1) for adsorption of Hg(2+) ions over the obtained adsorbent. The performance of adsorbent was examined on the real wastewaters and confirmed the applicability of adsorbent for practical applications.

Highly efficient simultaneous ultrasonic-assisted adsorption of Pb(II), Cd(II), Ni(II) and Cu (II) ions from aqueous solutions by graphene oxide modified with 2,2'-dipyridylamine: Central composite design optimization

In present work, a graphene oxide chemically modified with 2,2'-dipyridylamine (GO-DPA), was synthesized by simple, fast and low-cost process for the simultaneous adsorption of four toxic heavy metals, Pb(II), Cd(II), Ni(II) and Cu(II), from aqueous solutions. The synthesized adsorbent was characterized by FT-IR, XRD, XPS, SEM and AFM measurements. The effects of variables such as pH solution, initial ion concentrations, adsorbent dosage and sonicating time were investigated on adsorption efficiency by rotatable central composite design. The optimum conditions, specified as 8mg of adsorbent, 20mgL(-1) of each ion at pH 5 and short time of 4min led to the achievement of a high adsorption capacities. Ultrasonic power had important role in shortening the adsorption time of ions by enhancing the dispersion of adsorbent in solution. The adsorption kinetic studies and equilibrium isotherms for evaluating the mechanism of adsorption process showed a good fit to the pseudo-second order and Langmuir model, respectively. The maximum adsorption capacities (Qm) of this adsorbent were 369.749, 257.201, 180.893 and 358.824mgg(-1) for lead, cadmium, nickel and copper ions, respectively. The removal performance of adsorbent on the real wastewater samples also showed the feasibility of adsorbent for applying in industrial purposes.

Competitive removal of hazardous dyes from aqueous solution by MIL-68(Al): Derivative spectrophotometric method and response surface methodology approach

MIL-68(Al) as a metal-organic framework (MOF) was synthesized and characterized by different techniques such as SEM, BET, FTIR, and XRD analysis. This material was then applied for simulations removal of malachite green (MG) and methylene blue (MB) dyes from aqueous solutions using second order derivative spectrophotometric method (SODS) which was applied to resolve the overlap between the spectra of these dyes. The dependency of dyes removal efficiency in binary solutions was examined and optimized toward various parameters including initial dye concentration, pH of the solution, adsorbent dosage and ultrasonic contact time using central composite design (CCD) under response surface methodology (RSM) approach. The optimized experimental conditions were set as pH7.78, contact time 5min, initial MB concentration 22mgL(-1), initial MG concentration 12mgL(-1) and adsorbent dosage 0.0055g. The equilibrium data was fitted to isotherm models such as Langmuir, Freundlich and Tempkin and the results revealed the suitability of the Langmuir model. The maximum adsorption capacity of 666.67 and 153.85mgg(-1) was obtained for MB and MG removal respectively. Kinetics data fitting to pseudo-first order, pseudo-second order and Elovich models confirmed the applicability of pseudo-second order kinetic model for description of the mechanism and adsorption rate. Dye-loaded MIL-68(Al) can be easily regenerated using methanol and applied for three frequent sorption/desorption cycles with high performance. The impact of ionic strength on removal percentage of both dyes in binary mixture was studied by using NaCl and KCl soluble salts at different concentrations. According to our findings, only small dosage of the proposed MOF is considerably capable to remove large amounts of dyes at room temperature and in very short time that is a big advantage of MIL-68(Al) as a promising adsorbent for adsorptive removal processes.

Central composite design optimization of Ce(iii) ion removal from aqueous solution using modified SBA-15 mesoporous silica

HESI-SBA-15 was used as an effective adsorbent for cerium ion removal in real samples.

Highly efficient simultaneous ultrasonic-assisted adsorption of methylene blue and rhodamine B onto metal organic framework MIL-68(Al): central composite design optimization

In this work, metal organic framework (MIL-68(Al)), was synthesized by a simple, fast and low-cost process for simultaneous removal of methylene blue and Rhodamine B, regarded to be toxic and even carcinogenic, from aqueous solution.

Synthesis, characterization and application of cyclam-modified magnetic SBA-15 as a novel sorbent and its optimization by central composite design for adsorption and determination of trace amounts of lead ions

A new, efficient, selective and relatively low cost adsorbent was developed based on Fe₃O₄@cyclam-SBA-15 for adsorption and determination of lead ions.

Preparation and characterization of a novel tetrakis(4-hydroxyphenyl)porphyrin–graphene oxide nanocomposite and application in an optical sensor and determination of mercury ions

Optical chemical sensor for determination of mercury ions.

Design of a novel optical sensor for determination of trace gadolinium

In this work, a highly selective and sensitive gadolinium (Gd) optical sensor based on immobilization of bis(thiophenal) pyridine-2,6-diamine (BPD), on a triacetylcellulose membrane has been reported. This optode exhibits a linear range of the Gd(III) ion concentration of 2.5 x 10(-6)M with a detection limit of 0.93 x 10(-8) M. Response time of the newly designed optode was within 1-2 min, depending on the Gd(III) ion concentration. Response of the sensor is independent of solution pH in the range of 2.0-9.0. It manifests advantages of: low detection limit, fast response time, and most significantly, very good selectivity with respect to a number of lanthanide ions (La, Ce, Sm, Tm, Ho, and Eu ions). The sensor was successfully regenerated with thiourea solutions and its response was reversible and reproducible (R.S.D. less than 1.4%). This optode was applied to determine Gd(III) in synthetic and water samples, and validated with certified reference materials (CRMs).