Photodynamic therapy (PDT) is a promising cancer treatment modality that can selectively target unresectable tumors through optical activation of cytotoxic agents, thus reducing many side effects associated with systemic administration of chemotherapeutic drugs. However, limited light penetration into most biological tissues have so far prevented its widespread adoption beyond dermatology and a few other oncological applications in which a fiber optic can be threaded to the desired locations via an endoscopic approach (e.g., bladder). In this paper, we introduce an ultrasonically powered implantable microlight source, μLight, which enables in-situ localized light delivery to deep-seated solid tumors. Ultrasonic powering allows for small receiver form factor (mm-scale) and power transfer deep into the tissue (several centimeters). The implants consist of piezoelectric transducers measuring 2 × 2 × 2 mm3 and 2 × 4 × 2 mm3 with surface-mounted miniature red and blue LEDs. When energized with 185 mW/cm2 of transmitted acoustic power at 720 kHz, μLight can generate 0.048 to 6.5 mW/cm2 of optical power (depending on size of the piezoelectric element and light wavelength spectrum). This allows powering multiple receivers to a distance of 10 cm at therapeutic light output levels (a delivery of 20–40 J/cm2 light radiation dose in 1–2 hours). In vitro tests show that HeLa cells irradiated with μLights undergo a 70% decrease in average cell viability as compared to the control group. In vivo tests in mice implanted with 4T1-induced tumors (breast cancer) show light delivery capability at therapeutic dose levels. Overall, results indicate implanting multiple µLights and operating them for 1–2 hours can achieve cytotoxicity levels comparable to the clinically reported cases using external light sources.
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机译:光动力疗法(PDT)是一种有前途的癌症治疗方法,它可以通过细胞毒剂的光活化选择性地靶向不可切除的肿瘤,从而减少与化学治疗药物全身给药相关的许多副作用。然而,迄今为止,有限的光渗透到大多数生物组织中阻止了其在皮肤病学和其他一些肿瘤学应用中的广泛采用,在这些应用中,可以通过内窥镜方法(例如,膀胱)将光纤穿入所需的位置。在本文中,我们介绍了一种超声驱动的可植入微光源μLight,它能够将原位局部光传递到深层实体瘤。超声波供电可以实现较小的接收器外形尺寸(毫米级),并且可以将功率深深地传输到组织中(几厘米)。植入物由尺寸为2 measuring×2×2 mm 3 sup>和2×4×2 mm 3 sup>的压电传感器组成,表面安装了微型红色和蓝色LED。当在720 kHz的频率下以185 mW / cm 2 sup>的传输声功率通电时,μLight可以产生0.048至6.5 mW / cm 2 sup>的光功率(取决于压电体的尺寸)元素和光的波长光谱)。这样就可以在治疗光输出水平下向多个接收器供电,使其达到10 cm的距离(在1–2小时内提供20–40 J / cm 2 sup>光辐射剂量)。体外测试表明,与对照组相比,用μLights照射的HeLa细胞的平均细胞活力降低了70%。对植入了4T1诱导的肿瘤(乳腺癌)的小鼠进行的体内试验显示,在治疗剂量水平下,其光传输能力较高。总体而言,结果表明,植入多个µLights并运行1-2小时,可以达到与使用外部光源的临床报道病例相当的细胞毒性水平。
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