Iodinated Polyesters with Enhanced X-ray Contrast Properties for Biomedical Imaging

Abstract

Synthetic materials exhibiting contrast imaging properties have become vital to the field of biomedical imaging. However, polymeric biomaterials are lacking imaging contrast properties for deep tissue imaging. this report details the synthesis and characterization of a suite of aryl-iodo monomers, which were used to prepare iodinated polyesters using a pre-functionalization approach. commercially available 4-iodo-phenylalanine or 4-iodobenzyl bromide served as the starting materials for the synthesis of three iodinated monomeric moieties (a modified lactide, morpholine-2,5-dione, and caprolactone), which under a tin-mediated ring-opening polymerization (Rop), generated their respective polyesters (pe) or poly(ester amides) (peA). An increase in X-ray intensity of all synthesized iodine-containing polymers, in comparison to non-iodinated poly(lactic acid) (pLA), validated their functionality as radio-opaque materials. the iodinated-poly(lactic acid) (ipLA) material was visualized through varying thicknesses of chicken tissue, thus demonstrating its potenial as a radio-opaque biomaterial. Medical imaging, a technique that provides structural visualization inside the body, aides in the study of specific morphological changes within living and nonliving systems 1,2. One particular imaging modality, X-ray radiography, is frequently used as a diagnostic tool for non-invasive, in vivo, real-time examinations of three-dimensional opaque objects. X-ray imaging can be used to monitor response, degradation, and defects of biomedical devices 3. Concerns over the long-term stability of prolonged or permanent implantable devices have led to the development of polyester-based materials due to their desirable properties (i.e. biocompatibility, biodegradability, and facile synthesis) 4-8. The evolution of biodegradable polyester devices, like staples, stents, sutures, and implants, have had a significant impact on the biomedical field 4,9,10. Perhaps the most noteworthy advantage is their ability to be degraded and excreted from the body, obviating the need for their removal or surgical revision. This can be vital in major surgical procedures such as fracture fixation, spinal fixation, and abdominal wall repair 4,10. While commercially available polyester devices have seen a considerable amount of use in the biomedical field, their in vivo performance can be difficult to predict and evaluate due to the complex biological environment associated with tissues 10,11. Therefore, the real-time monitoring of these devices is critical in order to understand their performance and fate in the body. The major drawback of polyester-based devices is that they lack inherent contrast imaging properties, making it difficult to visualize the area of interest. Imaging techniques are useful only when the intensity of a signal is sufficient enough to distinguish the target from surrounding tissues or materials. This issue becomes even more evident when imaging materials through deep tissue or when monitoring minor defects in biomaterials 12. Recent ...

Rapid and Controlled Organocatalyzed Ring-Opening Polymerization of 3S-(Isobutyl)morpholine-2,5-dione and Copolymerization with Lactide

“…Employing the DBU/TU catalytic system, we also report for the first time on the organocatalyzed copolymerization of MD and (±)-lactide (LA) with varying ratios of LA. Copolymerizing morpholine-2,5-diones with other cyclic esters gives rise to interesting materials having reduced crystallinity and greater hydrophilicity when compared to the original polyesters, while allowing functionality to be introduced into the resulting materials. − Such properties can be very attractive for biomedical applications. , …”

Detection and Imaging of Damages and Defects in Fibre-Reinforced Composites by Magnetic Resonance Technique

“…The most recent attempt in this regard has been conducted by Vercio and Basmajian [ 33 ], who succeeded in identifying the gross failure of a carbon fibre-reinforced intramedullary nail, but did not prosper in characterizing the subtle discontinuities which could have led to the fracture event, due to the lack of sufficient image contrast to detect minor cracks and defects in the target device. The increasing risk of long-term effects of ionizing radiation, such as cancer, along with the expensive use of contrast enhancer gold coating incorporated into the composite material [ 34 ] and the need for a potentially allergenic intravenous iodinated radio-contrasting agent to overcome the typical radiolucency of polymer matrices [ 35 ], will most likely counteract the near-term implementation of X-ray techniques in this non-invasive procedure for permanent polymer-based structural implants [ 32 ].…”

Multiscale Live Imaging Using Förster Resonance Energy Transfer (FRET) for Evaluating the Biological Behavior of Nanoparticles as Drug Carriers

“…[4][5][6][7] Although PET, SPECT, and X-ray CT facilitate noninvasive live imaging because of the high tissue penetration of radiation, microscale observation is difficult owing to their low resolution. 8 Micro-CT enables higher resolution imaging with contrast agents [9][10][11][12] ; however, microscopic observation is additionally necessary for cellular scale imaging. Fluorescence imaging methods enable both macro-and microscale observation using various instruments including in vivo imagers and microscopes, although fluorescence imaging is often limited by the attenuation of light at certain wavelengths.…”