Blood-Brain Barrier (BBB) is one of the most important physiological barriers strictly restricting the substance exchange between blood and brain tissues. While the BBB protects the brain from infections and toxins and maintains brain homeostasis, it is also recognized as the main obstacle to the penetration of therapeutics and imaging agents into the brain. Due to high specificity and affinity, peptides are frequently exploited to decorate nanocarriers across the BBB for diagnosis and/or therapy purposes. However, there are still some challenges that restrict their clinical application, such as stability, safety and immunocompatibility. In this review, we summarize the biological and pathophysiological characteristics of the BBB, strategies across the BBB, and recent progress on peptide decorated nanocarriers for brain diseases diagnosis and therapy. The challenges and opportunities for their translation are also discussed.

血脑屏障（BBB）是严格限制血液和脑组织之间物质交换的最重要的生理屏障之一。虽然 BBB 保护大脑免受感染和毒素并维持大脑稳态，但它也被认为是治疗剂和显像剂渗透到大脑中的主要障碍。由于高特异性和亲和力，肽经常被用来装饰 BBB 上的纳米载体，用于诊断和/或治疗目的。然而，仍然存在一些限制其临床应用的挑战，例如稳定性、安全性和免疫相容性。在这篇综述中，我们总结了 BBB 的生物学和病理生理学特征、跨 BBB 的策略、以及用于脑疾病诊断和治疗的肽修饰纳米载体的最新进展。还讨论了他们翻译的挑战和机遇。