scholarly journals Concentration Effect over Thermoresponse Derived from Organometallic Compounds of Functionalized Poly(N-isopropylacrylamide-co-dopamine Methacrylamide)

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3921
Author(s):  
María Moral-Zamorano ◽  
Isabel Quijada-Garrido ◽  
Verónica San-Miguel ◽  
Berna Serrano ◽  
Juan Baselga ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Chemical Properties ◽  
Organometallic Compounds ◽  
Drug Carriers ◽  
Organometallic Complexes ◽  
Concentration Effect ◽  
Solution Temperature ◽  
Organometallic Complex ◽  
Vis Spectroscopy ◽  
Clear Idea

The functionalization of smart polymers is opening a new perspective in catalysis, drug carriers and biosensors, due to the fact that they can modulate the response regarding conventional devices. This smart response could be affected by the presence of organometallic complexes in terms of interactions which could affect the physical chemical properties. In this sense, the thermoresponsive behavior of copolymers based on N-isopropylacrylamide (NIPAM) could be affected due to the presence of hydrophobic groups and concentration effect. In this work, the functionalization of a copolymer based on NIPAM and dopamine methacrylamide with different amounts of bis(cyclopentadienyl)titanium (IV) dichloride was carried out. The resulting materials were characterized, showing a clear idea about the mechanism of functionalization through FTIR spectroscopy. The thermoresponsive behavior was also studied for various polymeric solutions in water by UV–vis spectroscopy and calorimetry. The hydrophobic interactions promoted by the organometallic complex could affect the transition associated with the lower critical solution temperature (LCST), specifically, the segments composed by pure NIPAM. That fact would explain the reduction of the width of the LCST-transition, contrary to what could be expected. In addition, the hydrophobicity was tested by the contact angle and also DNA interactions.

scholarly journals Effect of Hydrophobic Interactions on Lower Critical Solution Temperature for Poly(N-isopropylacrylamide-co-dopamine Methacrylamide) Copolymers

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 991 ◽  
Author(s):  
Alberto García-Peñas ◽  
Chandra Sekhar Biswas ◽  
Weijun Liang ◽  
Yu Wang ◽  
Pianpian Yang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Lower Critical Solution Temperature ◽  
Hydrophobic Interactions ◽  
Structural Information ◽  
Drug Carriers ◽  
Solution Temperature ◽  
Polymerization Degree ◽  
Tissue Engineering Scaffolds ◽  
Critical Solution Temperature ◽  
Precise Control

For the preparation of thermoresponsive copolymers, for e.g., tissue engineering scaffolds or drug carriers, a precise control of the synthesis parameters to set the lower critical solution temperature (LCST) is required. However, the correlations between molecular parameters and LCST are partially unknown and, furthermore, LCST is defined as an exact temperature, which oversimplifies the real situation. Here, random N-isopropylacrylamide (NIPAM)/dopamine methacrylamide (DMA) copolymers were prepared under a systematical variation of molecular weight and comonomer amount and their LCST in water studied by calorimetry, turbidimetry, and rheology. Structural information was deduced from observed transitions clarifying the contributions of molecular weight, comonomer content, end-group effect or polymerization degree on LCST, which were then statistically modeled. This proved that the LCST can be predicted through molecular structure and conditions of the solutions. While the hydrophobic DMA lowers the LCST especially the onset, polymerization degree has an important but smaller influence over all the whole LCST range.

scholarly journals Bypassing the Resistance Mechanisms of the Tumor Ecosystem by Targeting the Endoplasmic Reticulum Stress Pathway Using Ruthenium-and Osmium-Based Organometallic Compounds: An Exciting Long-Term Collaboration with Dr. Michel Pfeffer

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5386
Author(s):  
Gaiddon Christian ◽  
Gross Isabelle ◽  
Xiangjun Meng ◽  
Sidhoum Marjorie ◽  
Mellitzer Georg ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Ruthenium Complexes ◽  
Chemical Properties ◽  
Organometallic Compounds ◽  
Suppressor Gene ◽  
Resistance Mechanisms ◽  
Organometallic Complexes ◽  
Cell Death Pathway ◽  
Osmium Complexes ◽  
Stress Pathway

Metal complexes have been used to treat cancer since the discovery of cisplatin and its interaction with DNA in the 1960’s. Facing the resistance mechanisms against platinum salts and their side effects, safer therapeutic approaches have been sought through other metals, including ruthenium. In the early 2000s, Michel Pfeffer and his collaborators started to investigate the biological activity of organo-ruthenium/osmium complexes, demonstrating their ability to interfere with the activity of purified redox enzymes. Then, they discovered that these organo-ruthenium/osmium complexes could act independently of DNA damage and bypass the requirement for the tumor suppressor gene TP53 to induce the endoplasmic reticulum (ER) stress pathway, which is an original cell death pathway. They showed that other types of ruthenium complexes—as well complexes with other metals (osmium, iron, platinum)—can induce this pathway as well. They also demonstrated that ruthenium complexes accumulate in the ER after entering the cell using passive and active mechanisms. These particular physico-chemical properties of the organometallic complexes designed by Dr. Pfeffer contribute to their ability to reduce tumor growth and angiogenesis. Taken together, the pioneering work of Dr. Michel Pfeffer over his career provides us with a legacy that we have yet to fully embrace.

scholarly journals Sorption of diclofenac to selectively oxidised cellulose

2018 ◽  
Vol 72 (3) ◽  
pp. 167-176
Author(s):  
Pero Sailovic ◽  
Branka Rodic-Grabovac ◽  
Snezana Uletilovic
Keyword(s):  
Functional Groups ◽  
Chemical Bonding ◽  
Hydrophobic Interactions ◽  
Multiple Bond ◽  
Physiological Saline ◽  
Drug Carriers ◽  
Biologically Active ◽  
Oxidized Cellulose ◽  
Vis Spectroscopy ◽  
Two Samples

Biologically active fibers as drug carriers have improved characteristics in comparison with conventional medical therapies. Cellulose as a hydrophilic and biocompatible, nontoxic and eco-friendly material, makes a good polymer matrix for obtaining biologically active fibers. Loading drugs on the fiber carrier is accomplished through hydrophobic interactions, which is a prevailing mechanism of drug bonding. These interactions can be achieved by hydrophobic parts of the drug and the fiber carrier or by hydrophobic drugs themselves bonded on the fiber. In this paper, oxidized cellulose (OC) with 0.547, 1.163 and 2.199 mmol/g COOH is produced by using selective oxidation of a cellulose-based bandage. Oxidation has been carried out in mixture of HNO3/H3PO4 2:1 and 1.43 % NaNO2 for 5, 10 and 20 h at 25 ? 1 ?C. The OC sample with 2.199 mmol/g COOH showed the lowest sorption capacity as well as weak mechanical properties, so that the sorption experiments were not further pursued. The other two samples of oxidized cellulose with 0.547 and 1.163 mmol/g COOH have been used for chemical bonding of an analgesic, diclofenac, a derivative of potassium salt. Diclofenac in its structure contains two benzene rings which are linked via a secondary amine. The analgesic also contains a carboxyl group, as well as 2 chlorine atoms. As a result of the presence of these functional groups and structures, diclofenac can build multiple chemical bonds with an oxidized cellulose bandage. The chemical bonding of the drug has been performed using three analgesic solutions with concentrations of c = 2.5?10-3, 3.4?10-3 and 5.1?10-3 mol/L, at the temperature of 26 ? 1oC while desorption was performed in physiological saline solution. The amounts of bonded and released antibiotic were determined by UV-VIS spectroscopy at the wavelength of ?max=276 nm. The maximum amount of bonded drug (0.814 mmol/g OC) has been obtained by sorption from the solution of concentration c=5.1?10-3, while the highest amount of desorbed diclofenac was 0.063 mmol/g OC. The sorption kinetics has been succesfully described by the pseudo-second order model. It was established that the drug bonding was achieved by hydrogen bonds of the drug functional groups with the oxidised cellulose bandage. Low diclofenac relase from the oxsidiesed cellulose (12.5 % in 24 h) is a consequence of formation of multiple bond as well as drug aggregates on fiber surfaces.

Optimization of Gold Nanoparticles Synthesis using Design of Experiments Technique

2017 ◽  
Vol 68 (7) ◽  
pp. 1518-1423
Author(s):  
Adina Turcu Stiolica ◽  
Mariana Popescu ◽  
Maria Viorica Bubulica ◽  
Carmen Nicoleta Oancea ◽  
Claudiu Nicolicescu ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Zeta Potential ◽  
Design Of Experiments ◽  
Process Model ◽  
Sodium Citrate ◽  
Drug Carriers ◽  
Chloroauric Acid ◽  
Gold Colloids ◽  
Citrate Concentration ◽  
Vis Spectroscopy

Gold nanoparticles are considered the newest drug carriers for different diseases. Therefore it is appropriate continuous optimization of their preparation. In this study, gold colloids with an average size of 1 - 26 nm were obtained by the reduction of tetrachloroauric acid with trisodium citrate. The nanomaterials were characterized by UV-Vis spectroscopy and dynamic light scattering technique. In addition, zeta potential was measured for samples synthesized in order to determine the stability of the colloids. A Two-level Full Factorial design was chosen to determine the optimum set of process parameters (chloroauric acid concentration and sodium citrate concentration) and their effect on various gold nanoparticles characteristics (size and zeta potential). These effects were quantified using Design of Experiments (DoE) with 5 runs and 1 centerpoint. The selected objective and process model in this investigation are screening and interaction. Findings from this research show that to obtain particles larger than 35 nm, it is recommended to increase sodium citrate concentration, at low chloroauric acid values. These conditions will help to achieve smaller zeta potential, too.

Thermodynamics and acoustic effects of quercetin on micellization and interaction behaviour of CTAB in different hydroethanol solvent systems

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Vikrant Abbot ◽  
Poonam Sharma
Keyword(s):  
Pharmaceutical Industry ◽  
Hydrophobic Interactions ◽  
Chemical Properties ◽  
Formulation Development ◽  
Surfactant Interactions ◽  
Physico Chemical ◽  
Ultrasonic Sound ◽  
Apparent Molar Compressibility ◽  
Solvent Systems ◽  
Thermoacoustic Properties

AbstractFlavonoids amongst the class of secondary metabolites possess numerous health benefits, are known for its use in pharmaceutical industry. Quercetin, a flavonoid has more prominent medical advantages however its utilization is constrained because of various instability and insolubility issues and therefore, taken into consideration for studying its physico-chemical properties. In view of that, the thermodynamic and thermoacoustic properties of quercetin were examined in presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) at different hydroethanolic concentrations and temperatures. The conductivity studies were used to calculate change in enthalpy (∆Hom), change in entropy (∆Som) and change in Gibbs free Energy (∆Gom) of micellization. The interactions between quercetin and CTAB were found to be endothermic, entropically controlled and spontaneous. Further, ultrasonic sound velocity and density studies were carried out and utilized for the calculation of thermoacoustic parameters i.e. apparent molar volume and apparent molar compressibility. Thermoacoustic properties revealed that at higher surfactant concentration, hydrophobic interactions are dominant. The results suggested that the flavonoid-surfactant interactions in hydroethanolic solutions is more favourable as compared with aqueous solution. Overall, the data is favourable for the framework to be used for detailing advancement, drug development, drug industry, pharmaceutical industry, medical administration and formulation development studies.

scholarly journals Mesoporous Silica Nanoparticles for Targeting Subcellular Organelles

2020 ◽  
Vol 21 (24) ◽  
pp. 9696
Author(s):  
Miguel Gisbert-Garzarán ◽  
Daniel Lozano ◽  
María Vallet-Regí
Keyword(s):  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
State Of The Art ◽  
Mesoporous Silica Nanoparticles ◽  
Drug Distribution ◽  
Chemical Properties ◽  
Drug Carriers ◽  
Subcellular Organelles ◽  
Physico Chemical ◽  
Tumoral Cells

Current chemotherapy treatments lack great selectivity towards tumoral cells, which leads to nonspecific drug distribution and subsequent side effects. In this regard, the use of nanoparticles able to encapsulate and release therapeutic agents has attracted growing attention. In this sense, mesoporous silica nanoparticles (MSNs) have been widely employed as drug carriers owing to their exquisite physico-chemical properties. Because MSNs present a surface full of silanol groups, they can be easily functionalized to endow the nanoparticles with many different functionalities, including the introduction of moieties with affinity for the cell membrane or relevant compartments within the cell, thus increasing the efficacy of the treatments. This review manuscript will provide the state-of-the-art on MSNs functionalized for targeting subcellular compartments, focusing on the cytoplasm, the mitochondria, and the nucleus.

scholarly journals Polymeric Drug Delivery System Based on Pluronics for Cancer Treatment

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3610
Author(s):  
Jialin Yu ◽  
Huayu Qiu ◽  
Shouchun Yin ◽  
Hebin Wang ◽  
Yang Li
Keyword(s):  
Drug Delivery ◽  
Self Assembly ◽  
Drug Delivery Systems ◽  
Tumor Therapy ◽  
Chemical Properties ◽  
Drug Carriers ◽  
Disease Diagnosis ◽  
Delivery Systems ◽  
Polymeric Drug Delivery ◽  
Physical And Chemical

Pluronic polymers (pluronics) are a unique class of synthetic triblock copolymers containing hydrophobic polypropylene oxide (PPO) and hydrophilic polyethylene oxide (PEO) arranged in the PEO-PPO-PEO manner. Due to their excellent biocompatibility and amphiphilic properties, pluronics are an ideal and promising biological material, which is widely used in drug delivery, disease diagnosis, and treatment, among other applications. Through self-assembly or in combination with other materials, pluronics can form nano carriers with different morphologies, representing a kind of multifunctional pharmaceutical excipients. In recent years, the utilization of pluronic-based multi-functional drug carriers in tumor treatment has become widespread, and various responsive drug carriers are designed according to the characteristics of the tumor microenvironment, resulting in major progress in tumor therapy. This review introduces the specific role of pluronic-based polymer drug delivery systems in tumor therapy, focusing on their physical and chemical properties as well as the design aspects of pluronic polymers. Finally, using newer literature reports, this review provides insights into the future potential and challenges posed by different pluronic-based polymer drug delivery systems in tumor therapy.

Biosynthesis of selenium nanoparticles by Aspergillus flavus and Candida albicans and comparison of their effects with antifungal drugs

2021 ◽  
Author(s):  
Mahdi Hosseini Bafghi ◽  
Razieh Nazari ◽  
Majid Darroudi ◽  
Mohsen Zargar ◽  
Hossein Zarrinfar
Keyword(s):  
Candida Albicans ◽  
Aspergillus Flavus ◽  
Fungal Pathogens ◽  
Chemical Properties ◽  
Cost Effective ◽  
Antifungal Drugs ◽  
Selenium Nanoparticles ◽  
Fungal Strains ◽  
Vis Spectroscopy ◽  
Physical And Chemical

Abstract Biosynthesis of nanoparticles can stand as a replacement for the available chemical and physical methods by offering new procedures as green syntheses that have proved to be simple, biocompatible, safe, and cost-effective. Considering how nanoparticles with a size of 1 to 100 nanometers contain unique physical and chemical properties, recent reports are indicative of observing the antifungal qualities of selenium nanoparticles (Se-NPs). Recently, the observance of antifungal resistance towards different species of these fungi is often reported. Therefore, due to the antifungal effects of biological nanoparticles, this study aimed to investigate the exertion of these nanoparticles and evaluate their effects on the growth of fungal pathogens. Se-NPs were biosynthesized by the application of wet reduction method, which included specific concentrations of Aspergillus flavus and Candida albicans. The presence of nanoparticles was confirmed by methods such as UV-Vis spectroscopy, FT-IR analysis, and FESEM electron microscope that involved FESEM and EDAX diagram. The fungal strains were cultured in sabouraud dextrose agar medium to perform the sensitivity test based on the minimum inhibitory concentration (MIC) method in duplicate. The utilization of Se-NPs at concentrations of 1 µg/ ml and below resulted in zero growth of fungal agents. However, their growth was inhibited by antifungal drugs at concentrations of 2 µg/ ml and higher. Based on the obtained results, biological nanoparticles produced by fungal agents at different concentrations exhibited favorable inhibitory effects on the growth of fungal strains.

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

scholarly journals The Tribological and Chemical Properties of Ni-W Alloy Electrodeposition

2019 ◽  
Vol 26 (1) ◽  
pp. 145-149
Author(s):  
Mofeed A. Jaleel ◽  
Eilaf Z. Gurji
Keyword(s):  
Chemical Resistance ◽  
Low Carbon Steel ◽  
Chemical Properties ◽  
Solution Temperature ◽  
Major Influence ◽  
Deposition Condition ◽  
Low Carbon ◽  
Alloy Electrodeposition ◽  
Citrate Bath ◽  
And Chemical Properties

The Electrodeposition process has been used to substrate Ni-W alloy on low carbon steel by using ammonical citrate bath. The influence of deposition condition by variation of current density (0.04-0.2 A/cm2) and solution temperature (60-70 °C), on the mechanical and chemical properties such as (microhardness, wear resistance, residual stress and chemical resistance) was studied. Results show that the current efficiency has the major influence on the tungsten content in the alloys which reflected to the properties of the deposits.

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