Photoacoustic imaging (PAI) is a promising noninvasive technique for molecular and cellular characterization of cancer. Cancer detection by PAI is an area of active research, and the recent advent of contrast agents based on near-infrared (NIR)-absorbing dyes or organic/inorganic nanoparticles tremendously improved the specificity and the signal contrast. Here we report the photoacoustic (PA) signal enhancement produced by biodegradable passion fruit-like nanoarchitectures in phantoms and ex vivo. By this approach, the synergistic interaction between commercial NIR-fluorophores and ultrasmall metal nanoparticles is exploited to produce a PA signal enhancement in the biological window. Moreover, the degradation of the nanoarchitectures is investigated in physiological environment as reference matrix.

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Ref. [82] was not included in the originally published version of this article. It should be added to the second paragraph on page 7179, which then reads as follows: "More recently, the notion to exploit the natural tropism of cells, such as tumor-associated macrophages, [35][36][37][38][39] T cells, [40,82] mesenchymal stem cells, [41][42][43] and neural stem cells, [44,45] has begun to emerge as a radical alternative."Ref.

Photoacoustic imaging is an emerging technique. Although commercially available photoacoustic imaging systems currently exist, the technology is still in its infancy. Therefore, the design of stable phantoms is essential to achieve semiquantitative evaluation of the performance of a photoacoustic system and can help optimize the properties of contrast agents. We designed and developed a polydimethylsiloxane (PDMS) phantom with exceptionally fine geometry; the phantom was tested using photoacoustic experiments loaded with the standard indocyanine green dye and compared to an agar phantom pattern through polyethylene glycol-gold nanorods. The linearity of the photoacoustic signal with the nanoparticle number was assessed. The signal-tonoiseratio and contrast were employed as image quality parameters, and enhancements of up to 50 and up to 300%, respectively, were measured with the PDMS phantom with respect to the agar one. A tissue-mimicking (TM)-PDMS was prepared by adding TiO2 and India ink; photoacoustic tests were performed in order to compare the signal generated by the TM-PDMS and the biological tissue. The PDMS phantom can become a particularly promising tool in the field of photoacoustics for the evaluation of the performance of a PA system and as a model of the structure of vascularized soft tissues.

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The ability of new polymeric materials to provide excellent biomechanical properties expanded their potential for biomedical applications enormously. The use of non-invasive imaging modalities could provide crucial information to monitor the efficacy/effectiveness/efficiency of the new materials employed in 'regenerative' approaches, including scaffolds, hydrogels, self-assembling materials and nanosized structures. The assessment of the morpho-functional and metabolic changes of treated or implanted tissues, the visualization of sites of drug delivery and the real-time check of the in vivo efficacy of therapeutics could be achieved by non-invasive micro-and macro-imaging techniques. The macro-and nano-requirements of these new materials and their behaviour in vivo can be investigated using standard approaches such as computed tomography, MRI and ultrasound techniques and the emerging photoacoustic imaging. This paper presents recent advancements of ultrasonography and the novel photoacoustic technique to monitor the morpho-functional parameters of synthetic polymeric scaffolds and conduits in experimental models.

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Voxel dosimetry is becoming more and more important when performing therapy with tumor-seeking radiopharmaceuticals. The method presented here does not require calculating the S-values at the voxel level, and thus bypasses the mathematical problems linked to the convolution of 3D arrays and to the voxel size. In the paper, the results obtained with this new simplified method as well as the possibility of using it for other radionuclides commonly employed in therapy are discussed. The possibility of using the correct density value of the tissue/organs involved is also discussed.