Objective: To construct prostate-specific membrane antigen (PSMA)-targeting, indocyanine green (ICG)-loaded nanobubbles (NBs) for multimodal (ultrasound, photoacoustic and fluorescence) imaging of prostate cancer.
Methods: The mechanical oscillation method was used to prepare ICG-loaded photoacoustic NBs (ICG NBs). Then, PSMA-binding peptides were connected to the surface of ICG NBs using the biotin–avidin method to make targeted photoacoustic NBs, namely, PSMAP/ICG NBs. Their particle sizes, zeta potentials, and in vitro ultrasound, photoacoustic and fluorescence imaging were examined. Confocal laser scanning microscopy and flow cytometry were used to detect the binding ability of the PSMAP/ICG NBs to PSMA-positive LNCaP cells, C4-2 cells, and PSMA-negative PC-3 cells. The multimodal imaging effects of PSMAP/ICG NBs and ICG NBs were compared in nude mouse tumor xenografts.
Results: The particle size of the PSMAP/ICG NBs was approximately 457.7 nm, and the zeta potential was approximately − 23.5 mV. Both confocal laser scanning microscopy and flow cytometry confirmed that the PSMAP/ICG NBs could specifically bind to both LNCaP and C4-2 cells, but they rarely bound to PC-3 cells. The ultrasound, photoacoustic and fluorescence imaging intensities of the PSMAP/ICG NBs in vitro positively correlated with their concentrations. The ultrasound and photoacoustic imaging effects of the PSMAP/ICG NBs in LNCaP and C4-2 tumor xenografts were significantly enhanced compared with those in PC-3 tumor xenografts, which were characterized by a significantly increased duration of ultrasound enhancement and heightened photoacoustic signal intensity (P < 0.05). Fluorescence imaging showed that PSMAP/ICG NBs could accumulate in LNCaP and C4-2 tumor xenografts for a relatively long period.
Conclusion: The targeted photoacoustic nanobubbles prepared in this study can specifically bind to PSMA-positive prostate cancer cells and have the ability to enhance ultrasound, photoacoustic and fluorescence imaging of PSMA-positive tumor xenografts. Photoacoustic imaging could visually display the intensity of the red photoacoustic signal in the tumor region, providing a more intuitive imaging modality for targeted molecular imaging. This study presents a potential multimodal contrast agent for the accurate diagnosis and assessment of prostate cancer.

Keywords: prostate-specific membrane antigen, peptide, indocyanine green, targeted nanobubbles, ultrasound molecular imaging, photoacoustic imaging


中文翻译：

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携带吲哚菁绿的靶向纳米气泡用于前列腺癌的超声、光声和荧光成像。

目的：构建前列腺特异性膜抗原 (PSMA) 靶向、负载吲哚菁绿 (ICG) 的纳米气泡 (NBs)，用于前列腺癌的多模式（超声、光声和荧光）成像。
方法：采用机械振荡法制备载有 ICG 的光声 NB（ICG NB）。然后，使用生物素-亲和素方法将 PSMA 结合肽连接到 ICG NBs 的表面，以制备靶向光声 NBs，即 PSMAP/ICG NBs。检查了它们的粒径、zeta 电位和体外超声、光声和荧光成像。共聚焦激光扫描显微镜和流式细胞仪用于检测 PSMAP/ICG NB 与 PSMA 阳性 LNCaP 细胞、C4-2 细胞和 PSMA 阴性 PC-3 细胞的结合能力。在裸鼠肿瘤异种移植物中比较了 PSMAP/ICG NB 和 ICG NB 的多模态成像效果。
结果：PSMAP/ICG NB 的粒径约为 457.7 nm，zeta 电位约为 - 23.5 mV。共聚焦激光扫描显微镜和流式细胞术均证实 PSMAP/ICG NB 可以特异性结合 LNCaP 和 C4-2 细胞，但它们很少结合 PC-3 细胞。PSMAP/ICG NBs的体外超声、光声和荧光成像强度与其浓度呈正相关。与 PC-3 肿瘤异种移植物相比，PSMAP/ICG NBs 在 LNCaP 和 C4-2 肿瘤异种移植物中的超声和光声成像效果显着增强，其特点是超声增强持续时间显着增加，光声信号强度增强。 P < 0.05)。
结论：本研究制备的靶向光声纳米泡能够特异性结合PSMA阳性前列腺癌细胞，具有增强PSMA阳性肿瘤异种移植物的超声、光声和荧光成像的能力。光声成像可以直观地显示肿瘤区域红色光声信号的强度，为靶向分子成像提供更直观的成像方式。本研究提出了一种潜在的多模式造影剂，用于准确诊断和评估前列腺癌。

关键词：前列腺特异性膜抗原，多肽，吲哚菁绿，靶向纳米泡，超声分子成像，光声成像