Affinity and Inactivation of Bacterial Endotoxins for Medical Device Materials

Thrombospondin-1 Small Interfering RNA-Loaded Lipid Nanoparticles Inhibiting Intimal Hyperplasia of Electrospun Polycaprolactone Vascular Grafts

Synthetic vascular grafts are promising conduits for small caliber arteries. However, due to restenosis caused by intimal hyperplasia, they cannot keep long patency in vivo. In this work, through single cell RNA sequencing, we found that thrombospondin-1 (THBS1) was highly expressed in the regenerated smooth muscle cells (SMCs) in electrospun polycaprolactone (PCL) vascular grafts. The expression of THBS1 by injured SMCs was confirmed in a balloon-induced vascular injury model. Downregulation of Thbs1 expression maintained contractile phenotypes of SMCs and reduced neointimal hyperplasia after vascular injury via inhibition of FGFR1/EGR1 signaling by decreasing THBS1 expression. THBS1 small interfering RNA (THBS1-siRNA) was then loaded into macrophage membrane (MM) hybrid lipid nanoparticles (Lipid NP@MM), which were used to modify PCL vascular grafts via polydopamine (PDA) coatings. Lipid NP@MM not only protected THBS1-siRNA from degradation but also improved its internalization by SMCs to decrease the level of THBS1 expression. PCL vascular grafts modified with PDA coatings and Thbs1-siRNA-loaded Lipid NP@MM showed significantly reduced intimal hyperplasia. Thus, the downregulation of THBS1 expression in regenerated SMCs in vascular grafts is a promising strategy to inhibit intimal hyperplasia during vascular graft regeneration in vivo.

Electrochemical detection of bacterial endotoxin lipopolysaccharide (LPS) on gold electrode modified with DAL-PEG-DK5-PEG-OH - Antimicrobial peptide conjugate

This work describes fabrication of gold electrodes modified with peptide conjugate DAL-PEG-DK5-PEG-OH that enables ultra-sensitive detection of lipopolysaccharide (LPS) isolated from the reference strain of Escherichia coli O26:B6. The initial step of the established procedure implies immobilization of the fully protected DAL-PEG-DK5-PEG-OH peptide on the surface of the gold electrode previously modified by cysteamine. Then side chain- and Fmoc-deprotection was performed in situ on the electrode surface, followed by its incubation in 1 % of BSA solution to block non-specific bindings sites before LPS detection. The efficiency of the modification was confirmed by X-ray Photoelectron Spectroscopy (XPS) measurements. Additionally, the cyclic voltammetry (CV) and electrochemical impendance spectroscopy (EIS) were employed to monitor the effectiveness of each step of the modification. The obtained results confirmed that the presence of the surface-attached covalently bound peptide DAL-PEG-DK5-PEG-OH enables LPS detection by means of CV technique within the range from 5 × 10-13 to 5 × 10-4 g/mL in PBS solution. The established limit of detection (LOD) for EIS measurements was 4.93 × 10-21 g/mL with wide linear detection range from 5 × 10-21 to 5 × 10-14 g/mL in PBS solution. Furthermore, we confirmed the ability of the electrode to detect LPS in a complex biological samples, like mouse urine and human serum. The effectiveness of the electrodes in identifying LPS in both urine and serum matrices was confirmed for samples containing LPS at both 2.5 × 10-15 g/mL and 2.5 × 10-9 g/mL.