Synthesis and In Vitro Study of a Dual-Mode Probe Targeting Integrin αvβ3

pH-responsive albumin-mimetic synthetic nanoprobes for magnetic resonance/fluorescence imaging of thyroid cancer

The combination of magnetic resonance and fluorescence imaging in dual-modality imaging not only resolves the limitations of conventional single molecular imaging techniques in terms of specificity, sensitivity, and resolution but also expands the possibilities of molecular imaging techniques in diagnostics and therapeutic monitoring. Herein, a novel pH-responsive magnetic resonance/near-infrared fluorescence (MR/NIRF) nanoprobe (MnO2@BSA-Cy5.5) was successfully prepared by biomineralizing manganese dioxide (MnO2) with bovine serum albumin (BSA) while coupling fluorescent dye Cy5.5 for precise tumor detection and visualization. The synthesized MnO2@BSA-Cy5.5 nanoprobes were spherical particles of approximately 22.62 ± 3.31 nm in size, and their relaxation rates and T1 imaging signals were activated-enhanced in an acidic environment. Cytotoxicity assay and hematoxylin and eosin staining demonstrated that MnO2@BSA-Cy5.5 had low cytotoxicity and good biocompatibility. More importantly, active targeting via solid tumor albumin-binding protein receptor and enhanced permeability and retention effect, the probe can be specifically aggregated to the tumor site of the 8305C tumor model and exhibit excellent MR/NIRF imaging properties. Our results show that MnO2@BSA-Cy5.5 has high resolution and sensitivity in tumor imaging and is expected to be applied as an MR/NIRF contrast agent for accurate diagnosis of thyroid cancer.

A Dual-Mode Imaging Nanoparticle Probe Targeting PD-L1 for Triple-Negative Breast Cancer

Chemotherapy has remained the mainstay of treatment of triple-negative breast cancer; however, it is significantly limited by the associated side effects. PD-1/PD-L1 immune checkpoint inhibition therapy (ICI) has been a breakthrough for this patient population in recent years. PD-L1 expression is crucial in immunotherapy since it is a major predictor of PD-1/PD-L1 antibody response, emphasizing the significance of monitoring PD-L1 expression. Nonetheless, it is hard to assess the expression of PD-L1 before surgery, which has highlighted the urgency for a precise and noninvasive approach. Herein, we prepared a dual-mode imaging nanoparticle probe to detect PD-L1. The particle size, zeta potential, biocompatibility, and imaging ability of NPs were characterized. The synthesized NPs showed slight cytotoxicity and good T2 relaxivity. The targeted NPs accumulated more in 4T1 cells than nontargeted NPs in vitro. The in vivo experiment further demonstrated the distribution of targeted NPs in tumor tissues, with changes in NIRF and MR signals observed. Our study indicated that SPIO-aPD-L1-Cy5.5 NPs can be used to monitor PD-L1 expression in breast cancer as NIRF/MR contrast agents.

MR/NIRF Dual-Mode Imaging of αvβ3 Integrin-Overexpressing Tumors Using a Lipopeptide-Based Contrast Agent

Early diagnosis and noninvasive detection of hepatocellular carcinoma have profound clinical implications for treatment quality and improved prognosis. To obtain high-resolution macroscopic anatomical information and high-sensitivity microscopic optical signals to detect tumors, it is highly desirable to develop dual-mode magnetic resonance imaging (MRI) and near-infrared fluorescent (NIRF) probes. An MR/NIRF dual-mode targeted contrast agent was created by encapsulating cyclic arginine-glycine-aspartate (cRGD) and Cy5.5 in liposomes and characterized by the particle size distribution, cytotoxicity, targeting, and MRI relaxivity. The MR T2 intensity and fluorescence intensity were evaluated in the tumors, livers, and muscles after the injection of cRGD-Liposome-Cy5.5 and Liposome-Cy5.5 at different time points. The average size of cRGD-Liposome-Cy5.5 was 62.33 ± 4.648 nm. The transverse relaxivity (R2) values had a negative correlation with the concentration of molecular probes. The MR signal intensity was enhanced in tumors after the cRGD-Liposome-Cy5.5 injection and not enhanced in liver parenchyma and muscles at the same time. The fluorescence intensity was enhanced in tumors after cRGD-Liposome-Cy5.5 injection in the targeted group. cRGD -Liposome-Cy5.5 as an entirely organic T2-positive dual-mode MR/NIRF targeted contrast agent is therefore able to detect early-stage hepatocellular carcinoma by targeting integrin αvβ3, providing advantages for potential clinical utility and ease of clinical transformation.

Peptide-drug conjugate-based novel molecular drug delivery system in cancer

Drug delivery systems are generally believed to comprise drugs and excipients. A peptide-drug conjugate is a single molecule that can simultaneously play multiple roles in a drug delivery system, such as in vivo drug distribution, targeted release, and bioactivity functions. This molecule can be regarded as an integrated drug delivery system, so it is called a molecular drug delivery system. In the context of cancer therapy, a peptide-drug conjugate comprises a tumor-targeting peptide, a payload, and a linker. Tumor-targeting peptides specifically identify membrane receptors on tumor cells, improve drug-targeted therapeutic effects, and reduce toxic and side effects. Payloads with bioactive functions connect to tumor-targeting peptides through linkers. In this review, we explored ongoing clinical work on peptide-drug conjugates targeting various receptors. We discuss the binding mechanisms of tumor-targeting peptides and related receptors, as well as the limiting factors for peptide-drug conjugate-based molecular drug delivery systems.

Multimodal Theranostic Cyanine-Conjugated Gadolinium(III) Complex for In Vivo Imaging of Amyloid-β in an Alzheimer's Disease Mouse Model

Despite the wide use of magnetic resonance imaging (MRI) as a clinical diagnostic tool, there are still no clinically approved MRI contrast agents that can be applied for cerebral Alzheimer's disease (AD) biomarker imaging. We report here the design and development of the first amyloid-β (Aβ)-targeted, blood-brain barrier (BBB) penetrable theranostic Gd(DOTA)-cyanine dyad, which was synthesized by the conjugation of Gd(DOTA) complex and carbazole-based cyanine dye by the copper(I)-catalyzed azide-alkyne cycloaddition click reaction for imaging of Aβ in vivo and ex vivo in AD mouse models. This dyad, as a multimodal probe, possesses desirable multifunctional properties, including good biocompatibility, low cytotoxicity, high Aβ selectivity, strong fluorescence enhancement upon binding with Aβ species, good paramagnetic properties, high stability, good BBB penetrability, and fast elimination from the mouse. The longitudinal relaxivity (r₁) of the dyad was found to be 4.42 mM^-1 s^-1 at 3 T, suggesting it to be promising as a T₁-weighted MRI contrast agent. The probe has been successfully demonstrated to be able to be applied for one- and two-photon excited fluorescence and magnetic resonance (MR) imaging of Aβ in transgenic mouse models of AD. In addition, it can inhibit Aβ aggregation, protect against toxicity induced by Aβ, and suppress Aβ-induced reactive oxygen species (ROS) production. Our results demonstrate the highly promising theranostic capability of the dyad for diagnosis and therapy of AD and extraordinary potential for MRI of Aβ in humans.