scholarly journals Less Reactive Thiol Ligands: Key towards Highly Mucoadhesive Drug Delivery Systems

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1259 ◽  
Author(s):  
Iram Shahzadi ◽  
Andrea Fürst ◽  
Zeynep Burcu Akkus-Dagdeviren ◽  
Shumaila Arshad ◽  
Markus Kurpiers ◽  
...  
Keyword(s):  
Intestinal Mucosa ◽  
Polyacrylic Acid ◽  
Drug Delivery Systems ◽  
Bond Formation ◽  
Work Of Adhesion ◽  
Gel Layer ◽  
Thiol Ligands ◽  
Mucus Gel ◽  
Ft Ir ◽  
Acetyl Cysteine

As less reactive s-protected thiomers can likely interpenetrate the mucus gel layer to a higher extent before getting immobilized via disulfide bond formation with mucins, it was the aim of this study to develop a novel type of s-protected thiomer based on the less reactive substructure cysteine-N-acetyl cysteine (Cys-NAC) in order to obtain improved mucoadhesive properties. For this purpose, two types of s-protected thiomers, polyacrylic acid-cysteine-mercaptonicotinic acid (PAA-Cys-MNA) and polyacrylic acid-cysteine-N-acetyl cysteine (PAA-Cys-NAC), were synthesized and characterized by Fourier-transform infrared spectroscopy (FT-IR) and the quantification of attached disulfide ligands. The viscosity of both products was measured in the presence of NAC and mucus. Both thiomers were also evaluated regarding swelling behavior, tensile studies and retention time on the porcine intestinal mucosa. The FT-IR spectra confirmed the successful attachment of Cys-MNA and Cys-NAC ligands to PAA. The number of attached sulfhydryl groups was in the range of 660–683 µmol/g. The viscosity of both s-protected thiomers increased due to the addition of increasing amounts of NAC. The viscosity of the mucus increased in the presence of 1% PAA-Cys-MNA and PAA-Cys-NAC 5.6- and 10.9-fold, respectively, in comparison to only 1% PAA. Both s-protected thiomers showed higher water uptake than unmodified PAA. The maximum detachment force (MDF) and the total work of adhesion (TWA) increased in the case of PAA-Cys-MNA up to 1.4- and 1.6-fold and up to 2.4- and 2.8-fold in the case of PAA-Cys-NAC. The retention of PAA, PAA-Cys-MNA, and PAA-Cys-NAC on porcine intestinal mucosa was 25%, 49%, and 76% within 3 h, respectively. The results of this study provide evidence that less reactive s-protected thiomers exhibit higher mucoadhesive properties than highly reactive s-protected thiomers.

Polyacrylic Acid Modified Cerium Oxide Nanoparticles: Synthesis and Characterization as a Peroxidase Mimic for Non-Enzymatic H2O2 Sensor

2020 ◽  
Vol 16 (5) ◽  
pp. 816-828
Author(s):  
Gurdeep Rattu ◽  
Nishtha Khansili ◽  
Prayaga M. Krishna
Keyword(s):  
Hydrogen Peroxide ◽  
Cerium Oxide ◽  
Polyacrylic Acid ◽  
Spectroscopic Analysis ◽  
Cerium Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Peroxidase Mimic ◽  
Ft Ir ◽  
H2o2 Sensing ◽  
Fluorescence Spectrometer

Background: Cerium oxide nanoparticles (nanoceria) are efficient free-radical scavengers due to their dual valence state and thus exhibit optical and catalytic properties. Therefore, the main purpose of this work was to understand the peroxidase mimic activity of polymer-stabilized nanoceria for enzyme-less H2O2 sensing by fluorescence spectrometer. Objective: This research revealed the development of fluorescence hydrogen peroxide nanosensor based on the peroxidase-like activity of polyacrylic acid stabilized nanoceria (PAA-CeO2 Nps). Methods: PAA-CeO2 Nps were synthesized by simple cross-linking reaction at a low temperature and characterized by XRD, SEM, Zeta potential, TGA, FT-IR and UV-VIS spectroscopic analysis. H2O2 sensing was performed by a fluorescence spectrometer. Results:: The synthesized polymer nanocomposite was characterized by XRD, SEM, TGA, FT-IR and UV-VIS spectroscopic analysis. The XRD diffraction patterns confirmed the polycrystalline nature and SEM micrograph showed nanoparticles having hexagonal symmetry and crystallite size of 32 nm. The broad peak of Ce–O bond appeared at 508 cm-1. UV-VIS measurements revealed a welldefined absorbance peak around 315 nm and an optical band-gap of 3.17 eV. As synthesized PAACeO2 Nps effectively catalysed the decomposition of hydrogen peroxide (H2O2) into hydroxyl radicals. Then terephthalic acid was oxidized by hydroxyl radical to form a highly fluorescent product. Under optimized conditions, the linear range for determination of hydrogen peroxide was 0.01 - 0.2 mM with a limit of detection (LOD) of 1.2 μM. Conclusion: The proposed method is ideally suited for the sensing of H2O2 at a low cost and this detection system enabled the sensing of analytes (sugars), which can enzymatically generate hydrogen peroxide.

scholarly journals Colonisation of the colonic mucus gel layer with butyrogenic and hydrogenotropic bacteria in health and ulcerative colitis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helen Earley ◽  
Grainne Lennon ◽  
J. Calvin Coffey ◽  
Desmond C. Winter ◽  
P. Ronan O’Connell
Keyword(s):  
Ulcerative Colitis ◽  
Inverse Correlation ◽  
Primary Energy ◽  
Rt Pcr ◽  
Mucosal Integrity ◽  
Gel Layer ◽  
Active Colitis ◽  
Mucus Gel ◽  
By Products ◽  
Total Bacteria

AbstractButyrate is the primary energy source for colonocytes and is essential for mucosal integrity and repair. Butyrate deficiency as a result of colonic dysbiosis is a putative factor in ulcerative colitis (UC). Commensal microbes are butyrogenic, while others may inhibit butyrate, through hydrogenotropic activity. The aim of this study was to quantify butyrogenic and hydrogenotropic species and determine their relationship with inflammation within the colonic mucus gel layer (MGL). Mucosal brushings were obtained from 20 healthy controls (HC), 20 patients with active colitis (AC) and 14 with quiescent colitis (QUC). Abundance of each species was determined by RT-PCR. Inflammatory scores were available for each patient. Statistical analyses were performed using Mann–Whitney-U and Kruskall-Wallis tests. Butyrogenic R. hominis was more abundant in health than UC (p < 0.005), prior to normalisation against total bacteria. Hydrogenotropic B. wadsworthia was reduced in AC compared to HC and QUC (p < 0.005). An inverse correlation existed between inflammation and R. hominis (ρ − 0.460, p < 0.005) and B. wadsworthia (ρ − 0.646, p < 0.005). Other hydrogenotropic species did not widely colonise the MGL. These data support a role for butyrogenic bacteria in UC. Butyrate deficiency in UC may be related to reduced microbial production, rather than inhibition by microbial by-products.

Probing Inclusion Complexes of Pentoxifylline and Pralidoxim inside Cyclic Oligosaccharides by Physicochemical Methodologies

2019 ◽  
Vol 233 (8) ◽  
pp. 1109-1127
Author(s):  
Biraj Kumar Barman ◽  
Kanak Roy ◽  
Mahendra Nath Roy
Keyword(s):  
Surface Tension ◽  
Free Energy ◽  
Inclusion Complexes ◽  
Apparent Molar Volume ◽  
Nmr Spectra ◽  
Drug Delivery Systems ◽  
Surface Tension Data ◽  
H Nmr ◽  
Ft Ir ◽  
Inclusion Phenomena

Abstract Structurally different Molecules namely Pentoxifylline and Pralidoxim were chosen along with α-cyclodextrin and β-cyclodextrin to study host-guest inclusion phenomena. The formations of host guest inclusion complexes were confirmed by studying 1H-NMR spectra, FT-IR spectra, apparent molar volume and viscosity co-efficient. The stabilities of inclusion complexes were compared calculating the binding constant from UV-VIS spectroscopic study. The 1:1 stoichiometry of the inclusion complexes were also determined by analysing the Jobs plot and surface tension data. The values for Gibbs’ free energy were found negative for both the processes. Based on all the above experiments the inclusion processes were found feasible for both the compounds. These types of inclusion complexes are of high interest in the field of research and industry as these are used as drug delivery systems.

scholarly journals Histochemical Structure of the Mucus Gel Layer Coating the Fecal Surface of Rodents, Rabbits and Humans

2005 ◽  
Vol 51 (4) ◽  
pp. 287-291 ◽  
Author(s):  
Akira SHIMOTOYODOME ◽  
Shinichi MEGUO ◽  
Ichiro TOKIMITSU ◽  
Takashi SAKATA
Keyword(s):  
Gel Layer ◽  
Mucus Gel ◽  
Layer Coating

scholarly journals Colonisation of the Colonic Mucus Gel Layer With Butyrogenic and Hydrogenotropic Bacteria in Health and Ulcerative Colitis

2020 ◽  
Author(s):  
Helen Earley ◽  
Grainne Lennon ◽  
Desmond Winter ◽  
Calvin Coffey ◽  
Ronan O'Connell
Keyword(s):  
Ulcerative Colitis ◽  
Inverse Correlation ◽  
Inhibitory Effect ◽  
Primary Energy ◽  
Rt Pcr ◽  
Mucosal Integrity ◽  
Gel Layer ◽  
Active Colitis ◽  
Mucus Gel ◽  
By Products

Abstract Butyrate is the primary energy source for colonocytes and is essential for mucosal integrity and repair. Butyrate deficiency as a result of colonic dysbiosis is a putative factor in ulcerative colitis (UC). Commensal microbes are butyrogenic, while others have an inhibitory effect, through hydrogenotropic activity. The aim of this study was to quantify butyrogenic and hydrogenotropic species and determine their relationship with inflammation within the colonic mucus gel layer (MGL).Mucosal brushings were obtained from 20 patients with active colitis (AC), 20 healthy controls (HC) and 14 with quiescent colitis (QUC). Abundance of each species was determined by RT-PCR. Inflammatory scores were available for each patient. Statistical analyses were performed using Mann-Whitney-U and Kruskall-Wallis tests.Butyrogenic R. hominis was more abundant in health than UC (p<0.005). Hydrogenotropic B. wadsworthia was reduced in AC compared to HC and QUC (p<0.005). An inverse correlation existed between inflammation and R. hominis (ρ -0.460, p >0.005) and B. wadsworthia (ρ -0.646, p >0.005). Other hydrogenotropic species did not widely colonise the MGL. These data support a role for butyrogenic and some species of hydrogenotropic bacteria in UC. Butyrate deficiency in UC may be related to reduced microbial production, rather than inhibition by microbial by-products.

Carbonaceous minerals as corrosion products on the surface of bottles

2020 ◽  
Vol 61 (6) ◽  
pp. 185-191
Author(s):  
A. Özcan ◽  
◽  
B. Arman ◽  
S. Demirli ◽  
M. Orhon
Keyword(s):  
Analytical Techniques ◽  
Test Methods ◽  
Critical Parameters ◽  
Humid Atmosphere ◽  
Silanol Groups ◽  
Annealing Conditions ◽  
Gel Layer ◽  
Colour Scale ◽  
Blue Solution ◽  
Ft Ir

During the corrosion process, as the ion exchange between the surface of the glass and the water progresses, the chemical structure of the surface changes and different structural layers are formed. These layers are characterised by various analytical techniques such as EPMA, XRD, FT-IR, TG-DTA and ICP-OES. Three carbonate mineral species namely calcite (CaCO3), shortite (Na2Ca2(CO3)3) and nyerereite (Na2Ca(CO3)2) have been identified at the outermost deposition layer. Critical parameters that affect the formation of the alkali depleted and silica enriched gel layer are investigated using some special test methods. Methylene blue solution reacts with the silanol groups of gel layer leaving a blue tint behind, the intensity of which varies with the extent of corrosion as the amount of silanol groups outcropped due to the increase of the porous structure area. A colour scale is developed to determine the level of corrosion and the results are correlated with the results of other known chemical analysis methods. The effect of annealing conditions on the chemical resistance of the surfaces and the role of the shape of the bottles on the water condensation at humid atmosphere are studied. The results of acid treatment and re-annealing of the corroded surfaces are described.

scholarly journals Thinning of the Gastric Mucus Gel Layer in H Pylori Positive Subjects with Advancing Age

1997 ◽  
Vol 26 (suppl 3) ◽  
pp. P8-P8
Author(s):  
J Newton ◽  
N Jordan ◽  
G Williams ◽  
A Allen ◽  
O James ◽  
...  
Keyword(s):  
Gastric Mucus ◽  
Gel Layer ◽  
Mucus Gel ◽  
H Pylori

Synthesis and characterization of composite polysulfone membranes for desalination in nanofiltration technique

2010 ◽  
Vol 62 (11) ◽  
pp. 2655-2663 ◽  
Author(s):  
A. Akbari ◽  
M. Homayonfal ◽  
V. Jabbari
Keyword(s):  
Acrylic Acid ◽  
Polyacrylic Acid ◽  
Graft Polymerization ◽  
Irradiation Time ◽  
Polymerization Process ◽  
Synthesis And Characterization ◽  
Porous Support ◽  
Ft Ir

Composite nanofiltration (NF) membrane was developed polyacrylic acid (PAA) in situ UV graft polymerization process using ultrafiltration (UF) polysulfone (PSF) membrane as porous support. FT-IR spectra indicated that grafting was performed and it show peaks at 1,732 cm−1 and 3,396 cm−1 region for CO and OH starching bond of acrylic acid (AA) monomer, respectively. AFM microscopy showed the roughness of surface was reduced by increase of UV irradiation times. Effect of irradiation time on the grafting of acrylic acid (AA) in the same concentration was discussed. The salts rejection increase was accompanied with grafting of polysulfone (PSF) ultrafiltration (UF) membrane. The rejection of Na2SO4, MgSO4, NaCl and CaCl2 salts by PSF-grafted-PAA nanofiltration (NF) membrane was in 98, 60, 52 and 30% respectively, under 0.3 MPa.

Adsorptive Removal of Ni(II) Ions from Aqueous Solution by Polyacrylic Acid/Attapulgite Composite Hydrogels

2017 ◽  
Vol 727 ◽  
pp. 859-865 ◽  
Author(s):  
Yi Wei Zheng ◽  
Wen Wen Tao ◽  
Gui Fang Zhang ◽  
Chao Lv ◽  
Yi Ping Zhao ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Adsorption Capacity ◽  
Polyacrylic Acid ◽  
Swelling Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Adsorptive Removal ◽  
Composite Hydrogels ◽  
Ph Values ◽  
Ft Ir

Polyacrylic acid/attapulgite (PAA/ATP) composite hydrogels used for removal of heavy metal ions from aqueous solution was synthesized via radical polymerization with acrylic acid (AA) and attapulgite (ATP) modified by hydrochloric acid as adsorbent. Chemical composition of the modified ATP was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) and the morphology of the PAA/ATP hydrogels was characterized by scanning electron microscope (SEM), respectively. The swelling ratio, pH-sensitivity and adsorption performance of Ni (II) ions of the composite hydrogels were studied. The results showed the swelling ratio of the PAA/ATP composite hydrogels was higher than that of PAA hydrogels and the composite hydrogels displayed sensitivity to pH values with a sharp increase of swelling ratio when the pH values increased from 4 to 6. Comparing with PAA hydrogels, the composite hydrogels obtained a larger adsorption capacity of Ni (II) ions, the average adsorption capacity could reach 72.8 mg/g and adsorption ratio could reach 84%.

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