Safe imaging agents that are able to render the expression and distribution of cancer receptors, enzymes or other biomarkers would facilitate clinical screening of the disease. Here, we show that diamagnetic dextran particles that are coordinated to a urea-based targeting ligand for prostate-specific membrane antigen (PSMA) enable targeted magnetic resonance imaging (MRI) of the PSMA receptor. In a xenograft model of prostate cancer, micromolar concentrations of the dextran–ligand probe provided sufficient signal to specifically detect PSMA-expressing tumours via chemical exchange saturation transfer MRI. The dextran-based probe could be detected via the contrast that originated from dextran hydroxyl protons, thereby avoiding the need of chemical substitution for radioactive or metallic labelling. Because dextrans are currently used clinically, dextran-based contrast agents may help to extend receptor-targeted imaging to clinical MRI.

能够使癌症受体，酶或其他生物标记物表达和分布的安全显像剂将有助于疾病的临床筛查。在这里，我们显示，与前列腺特异性膜抗原（PSMA）的基于尿素的靶向配体协调的抗磁性右旋糖酐颗粒可实现PSMA受体的靶向磁共振成像（MRI）。在前列腺癌的异种移植模型中，葡聚糖-配体探针的微摩尔浓度可提供足够的信号，以通过化学交换饱和转移MRI特异性检测表达PSMA的肿瘤。可以通过源自右旋糖酐羟基质子的对比来检测基于右旋糖酐的探针，从而无需化学取代放射性标记或金属标记。由于右旋糖酐目前在临床上使用，