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Sonodynamic therapy (SDT) has emerged as an important modality for cancer treatment. SDT utilizes ultrasound excitation, which overcomes the limitations of light penetration in deep tumors, as encountered by photodynamic therapy (PDT) which uses optical excitations. A comparative study of these modalities using the same sensitizer drug can provide an assessment of their effects. However, the efficiency of SDT and PDT is low in a hypoxic tumor environment, which limits their applications. In this study, we report a hierarchical nanoformulation which contains a Food and Drug Administration (FDA) approved sensitizer chlorin, e6, and a uniquely stable high loading capacity oxygen carrier, perfluoropolyether. This oxygen carrier possesses no measurable cytotoxicity. It delivers oxygen to overcome hypoxia, and at the same time, boosts the efficiency of both SDT and PDT. Moreover, we comparatively analyzed the efficiency of SDT and PDT for tumor treatment throughout the depth of the tissue. Our study demonstrates that the strengths of PDT and SDT could be combined into a single multifunctional nanoplatform, which works well in the hypoxia environment and overcomes the limitations of each modality. The combination of deep tissue penetration by ultrasound and high spatial activation by light for selective treatment of single cells will significantly enhance the scope for therapeutic applications.

3D photoacoustic computed tomography (3D-PACT) has made great advances in volumetric imaging of biological tissues, with high spatial-temporal resolutions and large penetration depth. The development of 3D-PACT requires high-performance acoustic sensors with a small size, large detection bandwidth, and high sensitivity. In this work, we present a new high-frequency 3D-PACT system that uses a microring resonator (MRR) as the acoustic sensor. The MRR sensor has a size of 80 μm in diameter and was fabricated using the nanoimprint lithography technology. Using the MRR sensor, we have developed a transmission-mode 3D-PACT system that has achieved a detection bandwidth of ~23 MHz, an imaging depth of ~8 mm, a lateral resolution of 114 μm, and an axial resolution of 57 μm. We have demonstrated the 3D PACT’s performance on in vitro phantoms, ex vivo mouse brain, and in vivo mouse ear and tadpole. The MRR-based 3D-PACT system can be a promising tool for structural, functional, and molecular imaging of biological tissues at depths.

Capitalizing on the photoacoustic effect, we developed a new fingerprint sensing system that can reveal both fingerprints and underlying vascular structures at a high spatial resolution. Our system is built on a 15 MHz linear transducer array, a research ultrasound system, and a 532-nm pulsed laser. A 3D image was obtained by scanning the linear array over the fingertip. The acquired fingerprint images strongly agreed with the images acquired from ultrasound. Additional experiments were also conducted to investigate the effect of acoustic coupling. We discovered that high-quality fingerprint and vessel images can be acquired from both wet and dry fingers using our photoacoustic system. The reduced subdermal features in dry coupling can be enhanced through post-processing. Compared to existing fingerprint scanners, the photoacoustic approach provides a higher quality 3D image of the fingerprint, as well as unique subdermal vasculature structures, making the system almost impossible to counterfeit.