Various noninvasive imaging techniques are used to produce deep-tissue and high-resolution images for biomedical research and clinical purposes. Organic and inorganic bioimaging agents have been developed to enhance the resolution and contrast intensity. This paper describes the synthesis of polytetrafluoroethylene-like nanoparticles (PTFE≈ NPs), their characterization, biological activity, and bioimaging properties. Transmission electron microscopy (TEM) images showed the shape and the size of the as-obtained small and ultrasmall PTFE≈ NPs. Fourier transform infrared spectroscopy (FTIR) confirmed the PTFE-like character of the samples. X-ray diffraction (XRD) enabled the determination of the crystallization system, cell lattice, and index of crystallinity of the material in addition to the presence of titania (TiO2) as the contamination. These findings were corroborated by X-ray photoelectron spectroscopy (XPS) that identifies the chemical states of the elements present in the samples along with their atomic percentages allowing the determination of both the purity index of the sample and the nature of the impurities. Additionally, diffuse reflectance ultraviolet–visible spectroscopy (UV–vis) was used to further assess the optical properties of the materials. Importantly, PTFE≈ NPs showed significant in vitro and in vivo biocompatibility. Lastly, PTFE≈ NPs were tested for their ultrasound and X-ray contrast properties. Our encouraging preliminary results open new avenues for PTFE-like nanomaterials as a suitable multifunctional contrast agent for biomedical imaging applications. Combined with suitable surface chemistry and morphology design, these findings shed light to new opportunities offered by PTFE nanoparticles in the ever-booming biomedical field.

Ultrasound (US) and X-ray imaging are diagnostic methods that are commonly used to image internal body structures. Several organic and inorganic imaging contrast agents are commercially available. However, their synthesis and purification remain challenging, in addition to posing safety issues. Here, we report on the promise of widespread, safe, and easy-to-produce particulate calcium fluoride (part-CaF2) as a bimodal US and X-ray contrast agent. Pure and highly crystalline part-CaF2 is obtained using a cheap commercial product. Scanning electron microscopy (SEM) depicts the morphology of these particles, while energy-dispersive X-ray spectroscopy (EDS) confirms their chemical composition. Diffuse reflectance ultraviolet-visible spectroscopy highlights their insulating behavior. The X-ray diffraction (XRD) pattern reveals that part-CaF2 crystallizes in the face-centered cubic cell lattice. Further analyses regarding peak broadening are performed using the Scherrer and Williamson–Hall (W-H) methods, which pinpoint the small crystallite size and the presence of lattice strain. X-ray photoelectron spectroscopy (XPS) solely exhibits specific peaks related to CaF2, confirming the absence of any contamination. Additionally, in vitro cytotoxicity and in vivo maximum tolerated dose (MTD) tests prove the biocompatibility of part-CaF2. Finally, the results of the US and X-ray imaging tests strongly signal that part-CaF2 could be exploited in bimodal bioimaging applications. These findings may shed a new light on calcium fluoride and the opportunities it offers in biomedical engineering.

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