Simple structural indocyanine green-loaded microbubbles for dual-modality imaging and multi-synergistic photothermal therapy in prostate cancer

Dual-modal molecular imaging and therapeutic evaluation of coronary microvascular dysfunction using indocyanine green-doped targeted microbubbles

Coronary microvascular dysfunction (CMD), which causes a series of cardiovascular diseases, seriously endangers human health. However, precision diagnosis of CMD is still challenging due to the lack of sensitive probes and complementary imaging technologies. Herein, we demonstrate indocyanine green-doped targeted microbubbles (named T-MBs-ICG) as dual-modal probes for highly sensitive near-infrared (NIR) fluorescence imaging and high-resolution ultrasound imaging of CMD in mouse models. In vitro results show that T-MBs-ICG can specifically target fibrin, a specific CMD biomarker, via the cysteine-arginine-glutamate-lysine-alanine (CREKA) peptide modified on the surface of microbubbles. We further employ T-MBs-ICG to achieve NIR fluorescence imaging of injured myocardial tissue in a CMD mouse model, leading to a signal-to-background ratio (SBR) of up to 50, which is 20 fold higher than that of the non-targeted group. Furthermore, ultrasound molecular imaging of T-MBs-ICG is obtained within 60 s after intravenous injection, providing molecular information on ventricular and myocardial structures and fibrin with a resolution of 1.033 mm × 0.466 mm. More importantly, we utilize comprehensive dual-modal imaging of T-MBs-ICG to evaluate the therapeutic efficacy of rosuvastatin, a cardiovascular drug for the clinical treatment of CMD. Overall, the developed T-MBs-ICG probes with good biocompatibility exhibit great potential in the clinical diagnosis of CMD.

Photoacoustic signal enhancement in dual-contrast gastrin-releasing peptide receptor-targeted nanobubbles

Translatable imaging agents are a crucial element of successful molecular imaging. Photoacoustic molecular imaging relies on optical absorbing materials to generate a sufficient signal. However, few materials approved for human use can generate adequate photoacoustic responses. Here we report a new nanoengineering approach to further improve photoacoustic response from biocompatible materials. Our study shows that when optical absorbers are incorporated into the shell of a gaseous nanobubble, their photoacoustic signal can be significantly enhanced compared to the original form. As an example, we constructed nanobubbles using biocompatible indocyanine green (ICG) and biodegradable poly(lactic-co-glycolic acid) (PLGA). We demonstrated that these ICG nanobubbles generate a strong ultrasound signal and almost four-fold photoacoustic signal compared to the same concentration of ICG solution; our theoretical calculations corroborate this effect and elucidate the origin of the photoacoustic enhancement. To demonstrate their molecular imaging performance, we conjugated gastrin-releasing peptide receptor (GRPR) targeting ligands with the ICG nanobubbles. Our dual photoacoustic/ultrasound molecular imaging shows a more than three-fold enhancement in targeting specificity of the GRPR-targeted ICG nanobubbles, compared to untargeted nanobubbles or prostate cancer cells not expressing GRPR, in a prostate cancer xenograft mouse model in vivo.

Design Principles Governing the Development of Theranostic Anticancer Agents and Their Nanoformulations with Photoacoustic Properties

The unmet need to develop novel approaches for cancer diagnosis and treatment has led to the evolution of theranostic agents, which usually include, in addition to the anticancer drug, an imaging agent based mostly on fluorescent agents. Over the past few years, a non-invasive photoacoustic imaging modality has been effectively integrated into theranostic agents. Herein, we shed light on the design principles governing the development of theranostic agents with photoacoustic properties, which can be formulated into nanocarriers to enhance their potency. Specifically, we provide an extensive analysis of their individual constituents including the imaging dyes, drugs, linkers, targeting moieties, and their formulation into nanocarriers. Along these lines, we present numerous relevant paradigms. Finally, we discuss the clinical relevance of the specific strategy, as also the limitations and future perspectives, and through this review, we envisage paving the way for the development of theranostic agents endowed with photoacoustic properties as effective anticancer medicines.

A versatile nanoagent for multimodal imaging-guided photothermal and anti-inflammatory combination cancer therapy

Photothermal therapy (PTT) has drawn great attention in cancer treatment because of its minimal invasiveness and high spatiotemporal selectivity, but it still encounters severe obstacles like heat-resistance, metastasis and recurrence. A key reason for the treatment failure is the highly inflammatory tumor microenvironment caused by hyperthermia. A simultaneous anti-inflammatory therapy alongside the PTT has great potential for overcoming the drawbacks of PTT; however, it has been less reported and further study is urgently needed. In addition, as many inorganic photothermal agents have no inherent imaging capability, diagnostic strategies should be introduced to help identify cancerous lesions and find the best treatment time period for PTT. Herein, we developed a versatile theranostic nanoagent (named T-lipos-CPAuNCs) for synergistic multimodal imaging-guided photothermal/anti-inflammatory cancer therapy. Perfluorohexane (PFH) loaded AuNCs and the anti-inflammatory drug celecoxib were encapsulated into the tumor-targeting cyclic Arg-Gly-Asp (cRGD) peptide modified liposomes to form T-lipos-CPAuNCs. The T-lipos-CPAuNCs accumulated in the tumor tissue and selectively targeted the cancer cells, and converted photo to thermal energy under near-infrared (NIR) laser irradiation to kill the cancer cells by PTT. The high temperature further accelerated the release of celecoxib to exert an anti-inflammatory effect, while on the other hand led to liquid to gas phase transition of PFH to facilitate ultrasound (US) imaging. The T-lipos-CPAuNCs also exhibited photoacoustic (PA) imaging capability. In vitro and in vivo experiments established that under the guidance of multimodal imaging, T-lipos-CPAuNCs significantly suppressed the tumor growth by PTT and prevented tumor metastasis with non-apparent tumor inflammation. The developed theranostic nanosystem (T-lipos-CPAuNCs) shows great potential for PA/US multimodal imaging guided photothermal/anti-inflammatory combination cancer therapy.