title: Anti-biofouling conducting polymer nanoparticles as a label-free optical contrast agent for high resolution subsurface biomedical imaging.
abstract: Optical coherence tomography (OCT) is a modern high resolution subsurface medical imaging technique. Herein we describe: (i) the synthesis of a thiophene-functionalized oligo(ethylene glycol) methacrylate (OEGMA)-based statistical copolymer, denoted poly(2TMOI-OEGMA); (ii) the preparation of sterically-stabilized polypyrrole (PPy) nanoparticles of approximately 60 nm diameter; (iii) the evaluation of these nanoparticles as a NIR-absorbing optical contrast agent for high-resolution OCT imaging. We show that poly(2TMOI-OEGMA)-stabilized PPy nanoparticles exhibit similar optical properties to poly(vinyl alcohol) (PVA)-stabilized PPy nanoparticles of comparable size prepared using commercially available PVA. Spectroscopic measurements and Mie calculations indicate that both types of PPy nanoparticles strongly absorb NIR radiation above 1000 nm, suggesting their potential use as OCT contrast agents. In vitro OCT studies indicate that both types of PPy nanoparticles reduce NIR backscattering within homogeneous intralipid tissue phantoms, offering almost identical contrast performance in this medium. However, PVA-stabilized PPy nanoparticles became colloidally unstable when dispersed in physiological buffer and immersed in a solid biotissue phantom and hence failed to generate a strong contrast effect. In contrast, the poly(2TMOI-OEGMA)-stabilized PPy nanoparticles remained well-dispersed and hence exhibited a strong rapid onset contrast effect within the biotissue phantom under identical physiological conditions. Ex vivo studies performed on excised chicken and porcine skin tissue demonstrated that topical administration of a low concentration of poly(2TMOI-OEGMA)-stabilized PPy nanoparticles rapidly enhances OCT image contrast in both cases, allowing key tissue features to be readily identified.
authors: Department of Chemistry, The University of Sheffield, Yorkshire, S3 7HF, UK. k.m.au.mail1@gmail.com
authors: Kin Man
authors: KM
authors: Au
authors: Zenghai
authors: Z
authors: Lu
authors: Stephen J
authors: SJ
authors: Matcher
authors: Steven P
authors: SP
authors: Armes
mesh_terms: D000818:Animals; D057219:Biofouling / Q000517:prevention & control*; D002645:Chickens; D003287:Contrast Media / Q000737:chemistry; D003952:Diagnostic Imaging / Q000379:methods*; D004655:Emulsions / Q000737:chemistry; D008689:Methacrylates / Q000138:chemical synthesis; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D019047:Phantoms, Imaging; D010743:Phospholipids / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D011092:Polyethylene Glycols / Q000138:chemical synthesis; D011108:Polymers / Q000737:chemistry*; D011109:Polymethacrylic Acids; D011758:Pyrroles / Q000737:chemistry; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D013024:Soybean Oil / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013552:Swine; D041623:Tomography, Optical Coherence
chemical_list: D003287:Contrast Media; D004655:Emulsions; D008689:Methacrylates; D010743:Phospholipids; D011108:Polymers; D011109:Polymethacrylic Acids; D011758:Pyrroles; C528061:poly(poly(ethylene glycol)methacrylate); C545823:soybean oil, phospholipid emulsion; C067635:polypyrrole; D011092:Polyethylene Glycols; D013024:Soybean Oil
keywords: Conducting polymer nanoparticles; Optical coherence tomography; Optical contrast agent; Protein–nanoparticle interactions; Subsurface imaging