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An exceptionally productive and sustainable procedure is described in this paper to fabricate 1-(benzothiazolylamino) methyl-2-naphthols using a novel green nanocomposite of chitosan and diethylenetriamine-modified graphene oxide, supported methanesulfonic acid (Ch@GO-DETA.MSA.). For the synthesis of the nanocomposite, maleic anhydride was first attached to chitosan, and then, graphene oxide was modified by diethylenetriamine (GO@DETA). Subsequently, nanocomposite was prepared from the reaction of chitosan-g-maleic anhydride and GO@DETA. Finally, methane sulfonic acid was added to the nanocomposite to afford Ch@GO-DETA.MSA. Structural properties of the nanocomposite were explored through various techniques including X-ray diffraction (XRD), thermal gravimetric analysis (TGA), FTIR spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). 1-(Benzothiazolylamino) methyl-2-naphthols were efficiently prepared in high to excellent yields through a multicomponent reaction of 2-aminobenzothiazole, aryl aldehydes, and 2-naphthol using Ch@GO-DETA.MSA. nanocomposite under solvent-free conditions. The proposed protocol exhibited superiority over several published protocols due to its nontoxicity and eco-friendly, catalytic ability, short reaction times, generality, efficiency, solvent-free condition, and simple workup.

Magnetic nanoparticles (MNPs) have many unique properties such as non-toxicity, suitable thermal and chemical stability, designability for different applications, environmental friendliness, high s...

Epirubicin (EPI) is one of the standard anticancer drugs that apply for various cancers treatment. However, the accumulation of EPI in the human body can be highly toxic, and it causes inevitable harm to organs. As a result, the evaluation of low concentrations of this drug in body samples requires sensitive, rapid, and accurate analysis methods. The fluorescence method is an efficient way in comparison of the traditional methods such as liquid chromatography, capillary electrophoresis, and electrochemical methods. Herein, we synthesized a novel fluorescence nanosensor named CMC-CdTe/ZnS based on using quantum dots (QDs). The structure of the prepared nanosensor is confirmed by different analysis methods such as FT-IR, TGA, and TEM. Besides that, the fluorescence intensity response of CMC-CdTe/ZnS QDs in the presence of Epirubicin drug is investigated. Based on obtained results, not only this nanosensor developed, but also the fluorescence quenching was explained by the typical Stern–Volmer equation. The best linear quenching equation for entitled nanosensor in the presence of Epirubicin is F0/F = 0.0346Q + 1.08 (R2 = 0.99), and the detection limit of Epirubicin is around 0.04 × 10−6 mol/L at 25 °C. All of the results display that this method could be reliable and suitable approach for determination of Epirubicin in commercial samples as well.

Due to the increasing demand for monitoring diseases such as rising heart rate, diabetes, and ocular disorders wearable and implantable biomedical devices seems too essential for patients not only in the hospital but also at home or during working time. Researchers mostly try to offer valuable information on the conditions of patients as non-invasive, by using comfort biomedical device with a minimum side effect. So, small and self-powered with high sensitivity biomedical devices are recommended, among different power sources that introduced for devices, biofuel cells would be produced as power source for a range of medical devices because of its capability to generate sufficient power output compared to the primary power source. The nature of the electrode reaction and the nature of the biochemical reactions are some of the important parameters that are considered for the classification of fuel cells. Enzymatic biofuel cells due to high activity at mild conditions widely applied in pacemaker; glucometer; and smart contact lenses when compared to other kinds of biofuel cells. On the other hand, short lifespan is one of important limitations in this type of biofuel cells. So, the easiest way to overcome these challenges is to apply non-enzymatic ones. Recent studies have attempted to issue novel method for fabrication of non-enzymatic biofuel cell in order to produce a new generation which are inexpensive, disposable, selective, and sensitive in properties. However, consideration of researchers to the development of self-powered biomedical devices by using body fluids or providing electricity storage is rising.

In this study, a nanogel-hydrogel hybrid was synthesized to improve drug delivery system performance. First, poly (acrylic acid-N-isopropylacrylamide) nanoparticles were synthesized using acrylic acid, N-isopropylacrylamide, sodium dodecyl sulfate, and MBA in the presence of APS as a radical initiator. Then the synthesized (A-N) nanogel was added to a solution of chitosan in acetic acid and (A-N) nanogel/ CTS-A hydrogel was synthesized in the presence of AA, MBA and ASP. (A-N) nanogel/ CTS-A hydrogel was characterized by IR, SEM, EDX, TEM, DLS, TGA, DTG and BET techniques. Doxorubicin (DOX) solution was used to evaluate drug loading capacity and the amount of drug-loaded was calculated using UV analysis. Drug release behavior was investigated by placing DOX-loaded (A-N) nanogel/ CTS-A at different temperature and pH ranges. Our research indicated the drug release for both carriers was controlled by diffusion mechanism but, increasing of temperature had not influenced the drug release mechanism. However, this study suggests that by trapping nanoparticles in a hydrogel system, drug carriers with higher absorption capacity and slower kinetic release can be created.

An environmentally friendly, straightforward, and cheap synthesis of highly substituted functionalized pyrrole derivatives via one pot four-component reactions of 1,3-dicarbonyl compounds, amines, ...

In this study, a graphene oxide nanocomposite hydrogel (GONH) based on poly(acrylic acid) grafted onto a natural salep polysaccharide was synthesized and investigated as an adsorbent for the removal of cationic dye from aqueous solution. The GONH was characterized and the absorption characteristics of the GONH adsorbent were then examined using methyl violet dye. The sorption valence, the effect of the adsorbent dose, pH, contact time, temperature and dye concentration on the removal efficiency of the dye were studied. The assessment of the adsorption isotherms showed that the Langmuir model better fits the experimental data than the Freundlich model and the Ho–McKay kinetic equation better describes the absorption kinetics than the Lagergren equation. Also, the thermodynamic parameters computed from the sorption isotherms indicated a spontaneous absorption process. The GONH is an efficient adsorbent and could be used for separation aqueous solutions.

This paper describes the synthesis and characterization of a pH-responsive drug release system based on cadmium telluride quantum dots capped by fluorescent dye-labeled poly (N-(2-(2-amino-ethylamino)-ethyl methacrylamide) metal-chelating polymer. Fluorescent dye is a model for an active molecule which shows our polymer can be attached to bioactive agents such as antibody or a functional drug. Furthermore, it indicates the success of ligand exchange between anchor groups on polymer surface and QDs. The polymer was synthesized using reversible addition fragmentation chain transfer polymerization, resulting in polymers with controllable molecular weights and low polydispersities. The use of diethylenetriamine allows obtaining hydrophilic polymers with amine functional groups available for conjugation with QDs. Furthermore, the amine moieties of the polymer guarantee the pH sensitivity of the system. The obtained nano carrier was monodispersed with very small diameter around 4.5 nm which confirmed by TEM. The obtained nanoparticles show low cytotoxicity in cell viability studies. The release rates of doxorubicin (DOX) anticancer drug conjugates were studied at pH 5.4 and pH 7.4. The release behavior for DOX in pH 7.4 (pH of normal cells) is

Hydrogels, nanogels, and nanocomposites show increasing potential for application in drug delivery systems due to their good chemical and physical properties. Therefore, we were encouraged to combine them to produce a new compound with unique properties for drug release systems. To this aim, we first prepared poly [(N-isopropylacrylamide)-co-(2-dimethylamino ethyl methacrylate) nanogel by copolymerization processes and then added it into the solution of poly (2-dimethylamino ethyl methacrylate)] grafted onto salep. Through dropwise addition of mixed aqueous solution of iron salts into the prepared polymeric solution, a novel hydrogel nanocomposite with excellent pH, thermo, and magnetic responsive was fabricated. The obtained hydrogel nanocomposite were characterized by Fourier transform infrared spectroscopy, thermo gravimetric analysis, X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer, and atomic force micrographs. The dependence of swelling properties of hydrogel nanocomposite on the temperature, pH, and magnetic field were investigated. The release behavior of doxorubicin hydrochloride (DOX) drug from DOX loaded into synthesized hydrogel nanocomposite was investigated at different pHs, temperatures, and magnetic field. In addition, the drug release behavior from obtained hydrogel nanocomposite was monitored via different kinetic models. Lastly, the toxicity of the DOX and DOX-loaded hydrogel nanocomposite were studied on MCF-7 cells at different times. These results suggested that the obtained hydrogel nanocomposite might have high potential applications in drug delivery systems.

In this study, a facile method was introduced for preparation of a ligand-coated CdTe QDs (CdTe-L QDs) for applying as a new optical nano-sensor in determination of Cr3+ ions in aqueous solutions. The prepared CdTe-L QDs were characterized using different analytical techniques including transmission electron microscopy (TEM), UV-Vis, thermogravimetric (TG) analysis, Fourier-transform infrared (FTIR), and fluorescence spectroscopies. It was found that the fluorescence intensity of the CdTe-L QDs at 540 nm (excitation at 380 nm) was selectively quenched in the presence of trace amounts of Cr3+ ions in comparison to different metal ions. In other word, a simple, highly sensitive, selective, and rapid analytical approach was used for the determination of Cr3+ ions in the concentration range of 6.78 ± 0.05 × 10−8–3.70 ± 0.02 × 10−6 mol L−1 with a detection limit of 20.30 ± 0.03 × 10−9 mol L−1. Furthermore, the designed nano-sensor was well used for the quantification of Cr3+ ions in real samples with satisfactory analytical results, and the results were compared with the standard methods (inductively coupled plasma emission spectroscopy (ICP-OES)).

Herein, thermo/pH/magnetic-triple sensitive nanogel comprised of poly(N-isopropylacrylamide), poly(2-dimethylaminoethyl) methacrylate), sodium alginate, and magnetic graphene oxide were synthesized using N,N-methylenebisacrylamide as a crosslinking agent, sodium dodecylsulfate as a surfactant, and ammonium persulfate as an initiator. The size, chemical structure, thermal stability, and morphology of the prepared nanogel were characterized using different methods. Transmittance of the obtained nanogel was investigated at varying pH and temperature in the presence and absence of magnet. The drug loading ability of synthesized nanogel was examined at different times and concentrations of doxorubicin. Additionally, the release rate of doxorubicin as an anticancer drug from the loaded nanogel was studied at different pH and temperature in the presence and absence of magnet. The biological performance of the formed nanogel was evaluated by seeding it onto MCF-7 cells at different times and concentrations. It was found that this triple responsible nanogel might provide a perfect basis for controlled drug delivery systems.

A novel thermo/pH/magnetic-triple-responsive nanogel was synthesized by grafting N-isopropylacrylamide and acrylic acid onto sodium alginate to modify magnetic graphene oxide as a drug delivery system. The synthesized nanogel was characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), vibrating sample magnetometer (VSM), atomic force micrographs (AFM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The obtained nanogel displayed excellent reversible transmittance changes in response to pH, temperature, and magnetic field. The performance of the nanogels to load doxorubicin (DOX) drug and to sustain doxorubicin release was tested upon exposure to pH, temperature, and magnetic field variations. The mechanism of drug release was proposed in this paper by different kinetic models. In addition, the effects of nanogels and DOX-loaded nanogels on MCF-7 cells were examined and results were compared with free DOX drug. The in vitro results demonstrated that this triple-responsive nanogel can be an appropriate candidate for applications in cancer therapy.

In this work, as a novel fluorescent nano-sensor, a ligand-capped CdTe QDs (CdTe-L QDs) was designed for the detection and quantification of Cu2+ ions in environmental water samples. The synthesized QDs were characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FTIR), UV–Vis spectrophotometry and fluorescence spectroscopy. Optical properties of the produced nanosensor were monitored by UV–Vis and fluorescence spectrophotometry. It was observed that fluorescence intensity of the produced nano-sensor selectively quenched by adding Cu2+ ions in comparison to other metal ions tested. Using CdTe-L QDs, a rapid and facile analytical method was developed to determine Cu2+ ions in the concentration range of 5.16 ± 0.07 × 10− 8 mol L− 1–1.50 ± 0.03 × 10− 5 mol L− 1 with a detection limit of 1.55 ± 0.05 × 10− 8 mol L− 1. The nanosensor was successfully applied for the determination of Cu2+ ions in various water samples, and the results were compared with the standard method.

In this study microwave irradiation was used to synthesis the silver nanocomposite hydrogel and the usefulness as an adsorbent for the preconcentration, extraction and determination of methyl red (MR) from water by dispersive solid phase extraction method was evaluated. For this purpose, silver nanocomposite hydrogel (SNH) was synthesized and characterized by thermo-gravimetric (TG) analysis, FT-IR, TEM and SEM images. The effects of some important variables such as centrifuge time (min), the pH of the methyl red solution, amount of adsorbent (g), acetone volume (mL) and chloroform volume (mL) on methyl red removal were studied using central composite design (CCD) and the optimum experimental conditions were evaluated by the desirability function (DF) combined response surface methodology (RSM). Under the optimal experimental conditions, the detection limit was found to be 1.4 μg mL− 1 for MR adsorption. The limit of quantification and the linear range of calibration curve were 4.6 μg mL− 1 and 0.1–25 μg mL− 1, respectively.

Green chemistry is one of the most important routes for the synthesis of heterocyclic compounds. In this regard, the synthesis of 2-thioxoquinazolinone derivatives was achieved by condensation of versatile materials including isatoic anhydride, amine and potassium thiocyanate in the green medium of water. This convenient and efficient method affords the desired products with good to excellent yields.

Nanogels (NGs) are three-dimensional water soluble cross-linked hydrogel materials in the nanoscale size range with a high loading capacity for guest molecules and act as drug carrier systems. In the present work, a new type of thermo/pH sensitive NG comprising salep modified graphene oxide (SMGO) with branched N-isopropylacrylamide (NIPAM) and acrylic acid (AA) was prepared. The SMGO/P(NIPAM-co-AA) NGs exhibited nanoporous structure and spherical particles with diameters about 82nm as characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The samples were also characterized by Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) to further confirm about the formation of NGs. Doxorubicin (DOX) loaded SMGO/P(NIPAM-co-AA) NGs showed thermo/pH dependent releasing behavior: slow drug release at neutral pH and lower temperature but increased significantly in acidic pH and higher temperature, without any burst release. In addition, the NGs exhibited no effect on the cell viability in the tested concentration range up to 410μg/mL and drug release systems enhanced toxicity to HeLa cells when compared to the equivalent dose of the free drug. Overall, our results put forth NGs as potential candidates in the development of a new nanocarrier for anti-cancer drug delivery.

This study describes the development of a novel biocompatible nanogel/hydrogel nanocomposite system for long-term delivery of bioactive molecules. To this aim, the nanogels were synthesized via radical polymerization of poly(N-isopropylacrylamide). The nanogels were introduced during the formation of a hydrogel network to produce nanogel/hydrogel soft nanocomposites, while the biocompatible hydrogel was based on poly (acrylic acid) grafted onto κ-carrageenan polysaccharide with entrapped magnetic iron oxide nanoparticles as crosslinker. In these systems, by using stimuli-responsive functional polymers in both gels (nanogels and hydrogels), pH, thermal and magnetic-responsive properties can be brought to final soft nanocomposites. The obtained soft nanocomposite was characterized by Fourier transform infrared spectrum (FT-IR), thermogravimetric (TG) analysis, and scanning electron microscopy (SEM). This biopolymer based nanogel/hydrogel used as a prolonged releasing drug carrier for levodopa (L-DOPA) as a main drug for treating Parkinson's symptoms. The in vitro release of L-DOPA was investigated at different pHs. pH-dependent release of the active drug can be sustained for >11 days from this soft nanocomposite. The results demonstrated a sustained release model that can be extended for other drugs.

Current discovery of different modifications of multi walled carbon nanotubes has motivated research for their potential applications in various field such as adsorbent materials, and drug delivery. Many different modified carbon nanotubes have been achieved, including combinations with iron oxide nanoparticles (NPs) for their unique properties including magnetic properties, nontoxicity, biocompatibility and capability which have considerable impact on the delivery of the drug at the targeted area. However, one of the disadvantages of this nanocomposite in biological fluids is that iron oxide NPs might be quickly cleared by the bloodstream before realization of their targets. In order to overcome this obstacle, polymers could be used as stabilizer to achieve a highly stable NPs@MWCNT composite. As a result, a magnetic multi walled carbon nanotube hydrogel nanocomposite based on poly (acrylic acid) grafted onto salep was synthesized and then fully characterized by using FTIR spectroscopy, thermogravimetric analysis, EDAX spectrum, SEM, TEM, AFM images, and vibrating sample magnetometer (VSM) and synthesis mechanism was suggested. Besides, swelling kinetics and loading and releasing of tetracycline hydrochloride as a model drug in various conditions were also investigated.

The present study investigated antibiotic drug loading in metal–organic frameworks (MOFs). Porous zeolitic imidazolate frameworks (ZIFs) were synthesized under concentrated aqueous solution. A straightforward nano-precipitation method was used to prepare ciprofloxacin (CIP)-loaded ZIF-8 (CIP-ZIF-8). ZIF-8 and CIP-ZIF-8 were characterized by FT-IR spectroscopy, X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis, the BET nitrogen adsorption–desorption method, and UV-Vis spectroscopy. The thermal behavior of CIP-ZIF-8 was confirmed by thermal analyses. FT-IR spectroscopy illustrated the presence of functional groups of CIP and ZIF-8 frameworks in CIP-ZIF-8. ZIF-8 showed high loading capacity for the model antibiotic drug CIP with pH-sensitive release. The as-synthesized CIP-ZIF-8 possesses high drug loading efficiency (21%), and the release in pH 5.0 acetate buffer solutions (97%) was faster than in pH 7.4 phosphate buffers (83%). The antibacterial activities of ZIF-8 and CIP-ZIF-8 were tested against one Gram-positive and one Gram-negative species. The results showed that the synthesized materials had good growth inhibition against microorganisms.

Silver nanocomposite hydrogel (SNH) based on poly(acrylic acid) grafted onto salep was prepared without initiator and under just 2 min ultrasonic irradiation for the first time. The SNH was then applied as an adsorbent for Rhodamine removal from aqueous solution. The SNH adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy images and X-ray photoelectron spectroscopy. A 24 full factorial central composite design, a linear mathematical model representing the influence of different variables and their interactions, was successfully employed for experimental design and analysis of the results. Analysis of variance demonstrated that Rhodamine adsorption significantly increased with increases in the amount of adsorbent, extraction time, stirring rate of the solution and Rhodamine volume as donor phase volume, but slightly decreased with an increase in temperature and pH of Rhodamine solution. The adsorption behaviors showed that the adsorption kinetics were in good agreement with a pseudo-second-order model for Rhodamine removal from aqueous solution. Thermodynamic studies revealed the feasibility and exothermic nature of the system. Adsorption mechanism was studied through two important adsorption isotherm models (Langmuir and Freundlich models). Under the optimal experimental conditions, the detection limit was found to be 0.94 µg mL−1 for Rhodamine adsorption. The limit of quantification and the linear range of calibration curve were 3.14 µg mL−1 and 1.00–10.98 µg mL−1, respectively.

A new preconcentration method, magnetic dispersive micro solid phase extraction (MDMSPE) developed for separation and determination of mercury. In this technique, an appropriate mixture of extraction solvent, disperser solvent and nanomagnetite (Fe 3 O 4 )/chelating agent 1-(2-ethoxyphenyl)-3-(4-ethoxyphenyl) triazene functionalized multi-walled carbon nanotubes with silica shell, as an adsorbent injected rapidly into an aqueous solution containing mercury. After the proper contact time, the nano-adsorbent separated from the aqueous phase by applying magnetic field outside of the vial and transferred to another vial with the elution solvent. The residual solution determined by cold vapour atomic absorption spectroscopy. The main factors affected the preconcentration of mercury investigated and optimized, such as extraction and disperser solvent type, adsorbed amount, sample pH value, effluent concentration, extraction time, the volume of chelating agents and temperature. The adsorption equilibrium data obeyed the Langmuir isotherm models and the kinetic data were well suited to the pseudo-second-order model. Thermodynamic studies revealed the endothermic nature of the procedure. Under the optimum experimental conditions, the detection limit for Hg(II) found to be 1.5 ± 0.27 ng mL − 1 and its limit of quantification (LOQ) was 5.0 ± 0.32 ng mL − 1 (n = 5). The linear range of the calibration curve was 9 ± 0.51–1000 ± 0.03 ng mL − 1 with a correlation coefficient of 0.9994.

A novel CdTe quantum dots (QDs) were prepared in aqueous phase via a facile method. At first, poly (acrylic amide) grafted onto sodium alginate (PAAm-g-SA) were successfully synthesized and then TGA capped CdTe QDs (CdTe-TGA QDs) were embed into it. The prepared CdTe-PAAm-g-SA QDs were optimized and characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FT-IR), UV-vis and fluorescence spectroscopy. The characterization results indicated that CdTe-TGA QDs, with particles size of 2.90 nm, were uniformly dispersed on the chains of PAAm-g-SA biopolymer. CdTe-PAAm-g-SA QDs also exhibited excellent UV-vis absorption and high fluorescence intensity. To explore biological behavior of CdTe-PAAm-g-SA QDs, the interactions between CdTe-PAAm-g-SA QDs and human serum albumin (HSA) (or bovine serum albumin (BSA)) were investigated by cyclic voltammetry, FT-IR, UV-vis, and fluorescence spectroscopic. The results confirmed the formation of CdTe-PAAm-g-SA QDs-HSA (or BSA) complex with high binding affinities. The thermodynamic parameters (ΔG

Benzimidazoles, benzoxazoles, and benzothiazoles derivatives were synthesized from condensation of aldehydes and 1,2-phenylenediamine or ortho -aminophenol or ortho -aminothiophenol in the presence of catalytic amount of Fe(III)–Schiff base/SBA-15 in water medium. Short reaction times, good to excellent yields, easy availability, reusability, and use of an eco-friendly catalyst are some of the significant attributes of the present method.

Thermal dehydration kinetic of a novel swollen silver nanocomposite hydrogel (SNH), prepared based on poly(acrylic acid) grafted onto salep as a water soluble polysaccharide backbone, was studied by thermogravimetry under non-isothermal conditions. The values of apparent activation energies (Ea) and pre-exponential factors (A) for a set of reaction models at 5, 10, 15, and 20 K min−1 heating rates were determined. The dependence of the activation energy on the extent of conversion was obtained by the model-free methods. Apparent activation energy (Ea) of the process was calculated from Kissinger–Akahira–Sunose and Tang isoconversional methods. From the strong dependence of the Ea value on the extent of conversion (α) for the investigated process, it was found that the dehydration process of SNH is complex and we cannot explain the whole process by a single mechanism. In the low extent of conversion (α), Ea rapidly decreases and the dehydration process is complex and probably involving a combination of several processes. In the range of α = 0.40–0.90, Ea is nearly constant and the dehydration process can be assumed to follow a single-step reaction. The results obtained from Criado and Invariant kinetic methods, in the constant-Ea region, confirmed that probable model for the dehydration process agreed with R3 model.

An efficient synthesis of novel ethyl-1,3,4-triphenyl-1H-pyrazolo[3,4-b]pyridine-6-carboxylate products has been achieved via condensation of pyrazole-5-amine derivatives and activated carbonyl groups, in refluxing acetic acid. This process has been found to be useful in the preparation of new N-fused heterocycle products in good to excellent yields.

A novel series of benzo[4,5]imidazo[1,2- a ]pyridine derivatives is synthesized through the reaction of 2-(1 H -benzo[ d ]imidazol-2-yl)acetonitrile and different ethyl 2,4-dioxo-4-arylbutanoate derivatives in the presence of piperidine in refluxing EtOH. All the products are easily prepared within 25–45 min in good to excellent yields.

Two approaches were utilized and compared for designing a novel ultrasensitive fluorescent apta-nanobiosensor for fast and sensitive determination of digoxin (DX) in biological fluids. The nanobiosensors were fabricated using reduced graphene quantum dots (rGQDs) as an optical probe and DX aptamer as a sensing material. In the first approach, a label-free aptamer was directly interacted with rGQDs, caused an enhancement of the fluorescence intensity of rGQDs. By addition of the target molecule (DX) and formation of the aptamer-DX complex, the fluorescence intensity was decreased. The fluorescent quenching had a linear relation with the concentration of DX with limit of detection down to 29.87 ± 1.01 × 10−12 mol L−1. In the second approach, to improve the reproducibility and sensitivity of the biosensor, a labeled aptamer with amine groups was used. Through a two-steps process, DX was detected more accurately. Fluorescence intensity of rGQDs functionalized with aptamer was first turn-off using oxidized carbon nanotubes (CNTs) through a fluorescence resonance energy transfer (FRET) mechanism. Next, by addition of the target molecule (DX), and its interaction with aptamer, inhibited the connection between CNTs and rGQDs-aptamer, hence, fluorescence of rGQDs were recovered and turn-on. The second approach provided a simple, fast, inexpensive, reproducibility and ultrasensitive methods for determination of DX with ultra-low detection limits of 7.95 ± 0.22 × 10−12 mol L−1. Both designed luminescent apta-nanobiosensors were well used for the quantification of DX in human serum and urine with satisfactory analytical results.

A novel Schiff-base/SBA-15 nanoadsorbent was successfully synthesized by the reaction of salicylal- dehyde and (3-aminopropyl) trimethoxysilane in methanol and subsequent grafting with SBA-15. The morphology and structures of the as-synthesized Schiff-base/SBA-15 nanoadsorbent were characterized by powder X-ray dif- fraction, transmission electron microscopy, Fourier trans- form infrared spectroscopy, thermo-gravimetric analysis, and N2 adsorption/desorption isotherms. The obtained Schiff-base/SBA-15 nanoadsorbent was used for the removal of methylene blue (MB) from aqueous solutions. The effects of various parameters such as temperature, concentration, pH, and contact time were examined, and optimal experimental conditions were determined. The equilibrium isotherms were conducted using Freundlich and Langmuir models. The pseudo-first-order, pseudo- second-order, and intraparticle diffusion models were used to fit adsorption data in the kinetic studies. The thermo- dynamic parameters such as the standard enthalpy, stan- dard entropy, and standard free energy were evaluated. The obtained results indicated that the Schiff-base/SBA-15 nanoadsorbent is an efficient adsorbent for removing MB.

Zinc (II) diamine-sarcophagine (Zn (II) DiAmsar) as a water soluble hexadentate ligand was synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) and UV–visible (UV–vis) spectroscopy. The bindings of Zn (II) DiAmsar with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated under the simulative physiological conditions. To study this binding, the fluorescence spectra in combination with FT-IR, UV–vis, cyclic voltammetry (CV), and molecular docking techniques were used in the present work. The results indicate that Zn (II) DiAmsar quenched effectively the intrinsic fluorescence of HSA and BSA via a static quenching process. The fluorescence quenching data was also used to determine binding sites and binding constants at different temperatures. The calculated thermodynamic parameters ( ∆G °, ∆H °, and ∆S °) suggest that the binding process occurs spontaneously by involving hydrogen bond and van der Waals interactions. The distance between HSA (or BSA) as a donor and Zn (II) DiAmsar as an acceptor was obtained according to fluorescence resonance energy transfer (FRET). In addition, the docking results revealed the possible binding sites and assess the microenvironment around the bounded Zn (II) DiAmsar.

A novel, one-pot, simple, environmentally benign and efficient protocol has been employed for the synthesis of chromeno[4,3-b]quinoline derivatives in the presence of catalytic amounts of Cu(II)-Schiff base/SBA-15 under solvent-free conditions in excellent yields and rates.

In this work, we have successfully modified aqueous CdTe quantum dots (QDs) by a biopolymer based on poly (2-hydroxyethyl methacrylate) grafted onto salep via a facile method at room temperature. The obtained QDs were characterized using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The size of the prepared QDs was estimated around 1.5 nm by TEM and XRD. Optical properties of modified QDs were monitored by absorption and fluorescence spectrophotometers. It was found that the fluorescence intensity of CdTe QDs was enhanced after coating by biopolymer. Finally, the fluorescence intensity of CdTe QDs was investigated at different temperatures and times.

New types of silver nanoparticles (Ag NPs) were prepared by the reduction of silver trifluoroacetate with diamine-sarcophagine (DiAmsar) in DMF solution. Nanoparticles growth, morphology, and chemical composition were determined by ultraviolet–visible spectroscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy, respectively. The effect of prepared Ag NPs on the fluorescence quenching of the dyes rhodamine 6G and 4-hydroxycoumarin were investigated in different temperatures. The results of the quenching experiments were analyzed using Stern–Volmer equation. The Stern–Volmer constant values showed that the quenching efficiencies decreased as the temperature increases indicating that the quenching process was a dynamic-type quenching. Moreover, the energy transfer behavior between Ag NPs and dye molecules were interrogated using Forster/fluorescence resonance energy transfer and nanomaterial surface energy transfer models. The anti-bacterial activities of Ag NPs were assessed against the Staphylococcus aureus and Escherichia coli bacteria. Results showed that the entitled Ag NPs have excellent antibacterial properties.

Cu(II)–DiAmSar complex functionalized mesoporous SBA-15 silica support was employed for the synthesis of benzothiazole heterocycles in aqueous media as a green solvent with excellent yields. The resulting novel catalyst is extraordinarily stable and inhibits leaching of the metal ions from the SBA-15 support. Furthermore, it showed good heterogeneous catalytic activity in the synthesis of the previously mentioned heterocycles and could also be recycled from the reaction mixture and reused six times. The nature of the support after the anchoring of Cu(II)–DiAmSar complex on the surface of SBA-15 nanochannels and successful anchoring were examined using X-ray diffraction, transmission electron microscopy, nitrogen physical adsorption, Fourier transform infrared studies and thermogravimetric analysis.