Effect of gastric environment on Helicobacter pylori adhesion to a mucoadhesive polymer

Nogueira, Frederico; Gonçalves, Inês C.; Martins, M. Cristina L.

doi:10.1016/j.actbio.2012.09.011

Cited by 38 publications

(30 citation statements)

References 48 publications

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“…The relative atomic composition of chitosan films (Chit_b) is in accordance with previous reports [26,36]. XPS S2p high-resolution spectra were used to detect chemical modifications, since immobilization reactions were performed using sulfur bonds.…”

Section: Xpsmentioning

confidence: 63%

“…The spectrum of chitosan immersed in buffer (Chit_b) allows the identification of the characteristic absorption bands of chitosan, as described elsewhere [25,26,[34][35][36]. After reaction with NAC and Sp, the increase of the characteristic amide I IR absorption (1660 cm À1 ) confirms the covalent reaction between chitosan free amine groups and the terminal carboxylic groups of NAC or Sp.…”

Section: Irrasmentioning

confidence: 97%

“…Chitosan thin films were prepared by dispensing a drop of chitosan solution (0.4% in acetic acid w/v) [26] on the center of the Au substrates (150 ll for 1 Â 1 cm 2 substrates) placed in the spin coater equipment (Laurell Technologies Corporation) and spun at 9000 rpm for 1 min. Then, the newly prepared ultrathin films were neutralized with 0.1 M NaOH for 5 min and rinsed twice with MilliQ water.…”

Section: Preparation Of Chitosan Ultrathin Filmsmentioning

confidence: 99%

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Characterization of hLF1–11 immobilization onto chitosan ultrathin films, and its effects on antimicrobial activity

et al. 2014

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a b s t r a c t hLF1-11 (GRRRRSVQWCA) is an antimicrobial peptide (AMP) with high activity against methicillin-resistant Staphylococcus aureus (MRSA), the most prevalent species in implant-associated infection. In this work, the effect of the surface immobilization on hLF1-11 antimicrobial activity was studied. Immobilization was performed onto chitosan thin films as a model for an implant coating due to its reported osteogenic and antibacterial properties. Chitosan thin films were produced by spin-coating on gold surfaces. hLF1-11 was immobilized onto these films by its C-terminal cysteine in an orientation that exposes the antimicrobial activity-related arginine-rich portion of the peptide. Two levels of exposure (with and without a polyethylene glycol (PEG) spacer) were analyzed. Covalent immobilization was further compared with the AMP physical adsorption onto chitosan films. Surfaces were characterized using ellipsometry, contact angle measurements, atomic force microscopy, infrared and X-ray photoelectron spectroscopies and using a fluorimetric assay for hLF1-11 quantification. Surface antimicrobial activity was assessed through surface adhesion and viability assays using an MRSA (S. aureus ATCC 33591). The incorporation of hLF1-11 increased significantly bacterial adhesion to chitosan films. However, the presence of hLF1-11, namely when immobilized through a PEG spacer, decreased the viability of adherent bacteria with regard to the control surface. These results demonstrated that hLF1-11 after covalent immobilization by its cysteine can maintain activity, particularly if a spacer is applied. However, further studies, exploring the opposite orientation or the same C-terminal orientation, but non-cysteine related, can help to clarify the potential of the hLF1-11 immobilization strategy.

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Section: Xpsmentioning

confidence: 63%

Section: Irrasmentioning

confidence: 97%

Section: Preparation Of Chitosan Ultrathin Filmsmentioning

confidence: 99%

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Characterization of hLF1–11 immobilization onto chitosan ultrathin films, and its effects on antimicrobial activity

et al. 2014

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“…Briefly, commercial squid pen chitosan (France Chitine) was purified by the re-precipitation method [19] resulting on a molecular weight of 283,000-472,000 with a deacetylation degree (DD%) of~85%. Chitosan ultrathin films (Ch) were prepared by spin coating (9000 rpm during 1 min; Laurell Technologies Corporation, North Wales) a chitosan solution (0.4% in acetic acid w/v) [20] on the center of the Au substrates. The ultrathin films produced were then neutralized with 0.1 M NaOH and rinsed with MilliQ water.…”

Section: Preparation Of Chitosan Ultrathin Filmsmentioning

confidence: 99%

Dhvar5 antimicrobial peptide (AMP) chemoselective covalent immobilization results on higher antiadherence effect than simple physical adsorption

et al. 2015

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a b s t r a c tBacterial colonization and subsequent biofilm formation is still one of the major problems associated with medical devices. Antimicrobial peptides (AMP) immobilization onto biomaterials surface is a promising strategy to avoid bacterial colonization. However, a correct peptide orientation and exposure from the surface is essential to maintain AMP antimicrobial activity.This work aims to evaluate the effect of the immobilization on antibacterial activity of Dhvar5 (LLLFLLKKRKKRKY), an AMP with a head-to-tail amphipathicity. Dhvar5 was linked to thin chitosan coatings in i) a controlled orientation and exposure, testing covalent immobilization of its N-or C-terminus and using spacers with different lengths and flexibilities or in ii) a random orientation by physical adsorption. Chitosan coating was chosen due to its antimicrobial properties and readiness to be functionalized.Surface characterization demonstrated the chemoselective immobilization of the peptide with different spacers in a similar concentration (~2 ng/cm 2 ).Efficacy assays demonstrated that covalent immobilization of Dhvar5 exposing its cationic end, improves the chitosan coating antimicrobial effect by decreasing Methicillin-resistant Staphylococcus aureus (MRSA) colonization. This effect was enhanced when longer spacers were used independently of their flexibility. In opposite, immobilized Dhvar5 exposing its hydrophobic end has no effect on bacterial adhesion to chitosan, and when adsorbed in a random orientation even induces bacterial adhesion to chitosan coating.

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“…The cantilever spring constants, calibrated using the thermal method, were 0.01-0.025 N m 21 [30]. Force measurements were performed as described elsewhere [31], with modifications to what concerns the working buffer, which was constituted by PBS (pH ¼ 7.4), due to the fact that H. pylori uses its flagellar motility to cross the mucus layer that covers and protects the gastric cells and reach the gastric epithelium, where the pH is more neutral [32]. Once there, H. pylori is able to adhere to the surface of the gastric epithelial cells, namely by the Le b -BabA interaction.…”

Section: Force Measurements and Data Analysismentioning

confidence: 99%

Atomic force microscopy measurements reveal multiple bonds between Helicobacter pylori blood group antigen binding adhesin and Lewis b ligand

Parreira

Shi

Magalhães

et al. 2014

J. R. Soc. Interface.

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The strength of binding between the Helicobacter pylori blood group antigenbinding adhesin (BabA) and its cognate glycan receptor, the Lewis b blood group antigen (Le b ), was measured by means of atomic force microscopy. High-resolution measurements of rupture forces between single receptorligand pairs were performed between the purified BabA and immobilized Le b structures on self-assembled monolayers. Dynamic force spectroscopy revealed two similar but statistically different bond populations. These findings suggest that the BabA may form different adhesive attachments to the gastric mucosa in ways that enhance the efficiency and stability of bacterial adhesion.

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Effect of gastric environment on Helicobacter pylori adhesion to a mucoadhesive polymer

Cited by 38 publications

References 48 publications

Characterization of hLF1–11 immobilization onto chitosan ultrathin films, and its effects on antimicrobial activity

Characterization of hLF1–11 immobilization onto chitosan ultrathin films, and its effects on antimicrobial activity

Dhvar5 antimicrobial peptide (AMP) chemoselective covalent immobilization results on higher antiadherence effect than simple physical adsorption

Atomic force microscopy measurements reveal multiple bonds between Helicobacter pylori blood group antigen binding adhesin and Lewis b ligand

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