Molecular probes for biomembrane recognition

描述（由申请人提供）：目标是为临床前生物医学研究和人类临床应用生产新的成像探针和相关方案。第一个具体目标是发现小的合成分子，选择性地靶向阴离子细胞膜表面暴露的磷脂酰丝氨酸，并将它们与健康细胞的近中性膜表面区分开来。一个应用是细胞死亡成像，作为检测疾病和测量治疗效果的方法。初步研究表明，一类荧光锌配位配合物可以作为各种细胞和动物模型中死亡和垂死组织的光学成像探针。对健康组织的选择性非常高，尽管暴露的磷脂酰丝氨酸的结合亲和力是中等的（低微摩尔解离常数）。为了提高临床应用的细胞靶向性能，将采用系统的合成和筛选循环来寻找对磷脂酰丝氨酸具有500倍高结合亲和力的下一代化合物。这将使微剂量成为可能，这是成功翻译的关键。先导化合物的成像能力将在细胞培养和细胞死亡动物模型中进行评估，重点是生产第一套实用的光学成像探针，用于非侵入性评估抗癌治疗的疗效。第二个具体目标是使用近红外化学发光和荧光（CLF）纳米颗粒创建肿瘤平面光学成像的新范例。化学发光是热激活的（也就是说，不需要化学或电刺激），这意味着纳米颗粒可以在低温下储存，只有当加热到体温时，它们才会产生化学发光。在小鼠身上的初步结果表明，化学发光成像可以识别动物表面以下两厘米以上的目标部位，这比目前使用平面荧光成像所能达到的深度约为五倍。新的成像模式将通过使用自发前列腺癌和原位结肠癌的相对深层组织动物模型进行实验来证明。化学发光成像将用于定位纳米颗粒靶向的肿瘤组织，从同一标本上取下的薄组织学切片的荧光显微镜将量化肿瘤实质的吸收。这种新的成像技术的力量将被用来回答有关肿瘤血管穿透肽iRGD促进纳米颗粒进入肿瘤的能力的问题。

DESCRIPTION (provided by applicant): The objective is to produce new imaging probes and associated protocols for preclinical biomedical research and for clinical use in humans. The first specific aim is to discover small synthetic molecules that selectively target anionic cell membrane surfaces with exposed phosphatidylserine and distinguish them from the near-neutral membrane surfaces of healthy cells. One application is cell death imaging, as a method to detect disease and measure treatment efficacy. Preliminary work has shown that a family of fluorescent zinc coordination complexes can act as optical imaging probes for dead and dying tissue in various cell and animal models. The selectivity over healthy tissue is very high, even though binding affinities for exposed phosphatidylserine are moderate (low micromolar dissociation constants). To improve cell targeting performance for clinical applications, a systematic cycle of synthesis and screening will be employed to find next-generation compounds that have 500-fold higher binding affinity for phosphatidylserine. This will enable microdosing, which is the key to successful translation. The imaging ability of lead compounds will be evaluated in cell culture and animal models of cell death with a focus on producing the first set of practically useful, optical imaging probes for non-invasive assessment of the efficacy of anticancer therapies. The second specific aim is to create a new paradigm for planar optical imaging of tumors using near-infrared chemiluminescent and fluorescent (CLF) nanoparticles. The chemiluminescence is thermally-activated (that is, no chemical or electrical stimulus is needed) which means that the nanoparticles can be stored at low temperature and they only become chemiluminescent when warmed to body temperature. Preliminary results in mice show that chemiluminescence imaging permits identification of target sites that are more than two centimeters below the animal surface, which is about five times deeper than currently achieved using planar fluorescence imaging. The new imaging paradigm will be demonstrated by conducting experiments using relatively deep-tissue animal models of spontaneous prostate cancer and orthotopic colon cancer. Chemiluminescence imaging will be used to locate the tumor tissue that is targeted by the nanoparticles, and fluorescence microscopy of thin histology sections taken from the same specimen will quantify uptake into the tumor parenchyma. The power of this new imaging technology will be employed to answer questions concerning the ability of the tumor vascular-penetrating peptide iRGD to promote nanoparticle entry into tumors.