Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: Characterization of LL-37-TiO 2 NPs. (A) ζ-potential and average particle size of bare TiO 2 NPs (100 ppm) in 10 mM acetate (pH 3.4 and 5.4) or 10 mM Tris (pH 7.4 and 9.4). (B) ζ-potential and average particle size of TiO 2 nanoparticles (100 ppm) loaded at varying concentrations of LL-37 in 10 mM Tris, pH 7.4 ( n = 3). (C) C 11 –BODIPY oxidation rates for bare or LL-37-coated TiO 2 NPs for +PG LUVs subjected to in situ UV exposure in 10 mM Tris, pH 7.4 ( n = 3). Corresponding oxidation kinetics are shown in Figure S1 . (D) ζ-potential of TiO 2 NPs coated with 50 μM LL-37 in 10 mM Tris, pH 7.4, before and after 1 or 2 h of UV illumination. Results are means ± SEM of n = 3 experiments.

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: In Situ

Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: Cryo-TEM images of 100 ppm smooth LPS (top), rough LPS (middle), and LTA (bottom) in 10 mM Tris, pH 7.4 (left), as well as the corresponding systems in the presence of 100 ppm of LL-37-TiO 2 NPs, either before (middle) and after (right) 2 h of UV illumination. The structural features of LPS and LTA (without LL-37-TiO 2 NPs) are highlighted in far-left insets, showing the formation of fibrillae with a diameter of ∼5 nm for smooth LPS, twisted ribbon-like structures of ∼22 nm in thickness and ∼140 nm characteristic node-to-node distance for rough LPS, and amorphous nanosized assemblies for LTA. Incubation with LL-37-TiO 2 NPs leads to aggregates of smooth LPS, rough LPS, and LTA, homogeneously decorated with NPs. UV illumination results in an increased packing density of such aggregates ( Figure ) and triggers the formation of characteristic structures (highlighted in the far-right insets), consisting of amorphous NP-decorated spherical assemblies (mostly observed in smooth LPS samples), free LPS fragments (mostly clearly seen in rough LPS samples), and multilamellar plate-like structures (present in both LPS and LTA samples).

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: Incubation

Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: Quantification of the compactness of LL-37-TiO 2 coaggregates with LPS and LTA obtained through cryo-TEM image analysis with the software ImageJ. , The procedure adopted for image analysis is shown in panel A for the representative images of smooth LPS/LL-37-TiO 2 coaggregates, acquired before (left image) or after (right image) 2 h of UV illumination. Black and white mask images were obtained from original cryo-TEM images to allow precise mapping of the edges of LL-37-TiO 2 /LPS or -LTA coaggregates over the cryo-TEM grid. LL-37-TiO 2 /LPS or -LTA aggregates were analyzed individually by selecting specific portions of the mask (e.g., areas highlighted in white in panel A). For aggregates smaller than the typical size of the holes in the cryo-TEM grid, the smallest circular areas fully enclosing the edges of single aggregates were selected. For aggregates exceeding this size, the largest circular areas enclosed within single grid holes were analyzed. The surface density of the aggregates (%) was then obtained over such selected portions as the ratio between the area occupied by the aggregate (in white) and the empty area (in black) and averaged over a large number of aggregates. Aggregate surface densities (%) for the different samples, before and after UV illumination, are reported in panel B. Shown in panel C are also the percentage increases in the aggregates surface density (%) on UV exposure. Results reported in panels B and C are means ± SEM of n ≥ 20 aggregates per sample.

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: Software

Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: QCM-d results showing frequency shifts caused by (A) binding of 100 ppm LL-37-TiO 2 NPs to smooth LPS, rough LPS, lipid A, and LTA and (B) effects of 2 h of in situ UV illumination for smooth LPS, rough LPS, lipid A, and LTA interacting with 100 ppm LL-37-TiO 2 . Results are shown for the adsorption to hydrophobic polystyrene surfaces coated with smooth LPS, rough LPS, lipid A, and LTA prepared as in Figure . Δ F = 0 corresponds to the frequency shift for the smooth LPS, rough LPS, and lipid A layers right before NP addition (A) or UV illumination (B). All measurements were performed in 10 mM Tris + NaCl 150 mM, pH 7.4. Representative QCM-d profiles for panels A and B are shown in Figure S7 , while the corresponding results for bare TiO 2 NPs are shown in Figures S5 and S6 . Results are means ± SEM of n = 3 experiments.

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: QCM-D, Binding Assay, In Situ, Adsorption

Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: Structural effects on OTS + lipid A (top), core oligosaccharide (middle), and O-antigen chain (bottom) layers induced by bare and LL-37-coated TiO 2 NPs in the absence and presence of UV illumination. Results were obtained from neutron reflectometry fits, calculating the physical parameters of the bilayers at different time points: (1) before NP incubation, (2) after NP incubation, and (3) after 2 h of in situ UV exposure. Shown are changes in the thickness (A) and hydration (B) for the three different layers, as well as a schematic illustration (C) describing the main structural changes observed for the different LPS domains upon NP interaction and UV illumination. Corresponding experimental curves, best curve fits and calculated SLD profiles, are shown in Figure S9 , while Figure S8 collects experimental curves, together with best curve fits and SLD profiles, for the neat OTS layer grafted before LPS deposition.

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: Incubation, In Situ

Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: (A) NF-κB/AP-1 activation and (B) LDH release induced by smooth (left) and rough (middle) LPS, as well as LTA (right), in the absence and presence of bare TiO 2 or LL-37-TiO 2 NPs in 10 mM Tris, pH 7.4, either before or after 2 h of UV illumination, using THP1-XBlue-CD14 reporter monocytes. The dashed lines in the graphs represent the NF-κB/AP-1 activation or LDH release for the control sample, i.e., 10 mM Tris buffer, pH 7.4, in the absence of LPS, LTA, and NPs. Results are mean ± SEM of 3–7 experiments. Values are significantly different (* p < 0.05, ** p < 0.005, and *** p < 0.0005) as analyzed using a one-tailed paired t test.

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: Activation Assay, Control, One-tailed Test

Journal: ACS Applied Materials & Interfaces

Article Title: Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO 2 Nanoparticles

doi: 10.1021/acsami.4c15706

Figure Lengend Snippet: Schematic illustration of key findings of the study: LL-37 coatings on TiO 2 NPs did not detrimentally interfere with ROS generation and displayed good stability on UV exposure. As a result, binding of net cationic LL-37-TiO 2 NPs to anionic Gram-negative LPS, its lipid A moiety, and Gram-positive LTA was much higher than that to weakly charged bare TiO 2 NPs. Mirroring this, LL-37-TiO 2 displayed potent capturing and UV-induced degradation fragments from LPS and LTA. While qualitatively similar effects were observed for polyarginine-coated NPs, oxidative degradation for all systems was lower than that for LL-37-TiO 2 NPs, likely due to electrostatic arrest preventing the highly cationic polyarginine NPs from effectively incorporating into the lipopolysaccharide layers. Mirroring the effects observed in model lipopolysaccharide systems, LL-37-coated TiO 2 NPs displayed boosted anti-inflammatory effects induced by both LPS and LTA at UV illumination, whereas toxicity against human monocytes remained low.

Article Snippet: Samples were then incubated for 2 h at room temperature with or without UV illumination (Spectroline ENF-260C, 254 nm, 3 mW/cm 2 ).

Techniques: Binding Assay