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Magnetic resonance imaging (MRI) and optical imaging (OI) are attractive for constructing bimodal probes due to their complementary imaging characteristics. The combination of these two techniques could be a useful tool to simultaneously obtain both anatomical and molecular information as well as to significantly improve the accuracy of detection. In this study, we found that β-diketonate-lanthanide complexes, BHHBCB-Ln3+, could covalently bind to proteins to exhibit long-lived and intense luminescence (Ln3+ = Eu3+, τ = 0.52 ms, Φ = 0.40) and remarkably high relaxivity (Ln3+ = Gd3+, r1 = 35.67 mM-1 s-1, r2 = 43.25 mM-1 s-1) with excellent water solubility, stability and biocompatibility. Hence, we conjugated BHHBCB-Ln3+ with a tumor-targetable biomacromolecule, transferrin (Tf), to construct the probes, Tf-BHHBCB-Ln3+, for time-gated luminescence (TGL, Ln3+ = Eu3+) and MR (Ln3+ = Gd3+) imaging of cancerous cells in vitro and in vivo. As expected, the as-prepared probes showed high specificity to bind with the transferrin receptor-overexpressed cancerous cells, to enable the probe molecules to be accumulated in these cells. Using Tf-BHHBCB-Ln3+ as probes, the cultured cancerous cells and the tumors in tumor-bearing mice have been clearly visualized by background-free TGL and in vivo MR imaging. The research outcomes suggested the potential of β-diketonate-lanthanide complexes for use in constructing bimodal TGL/MR imaging bioprobes.

Probes combining luminescence and magnetic resonance (MR) imaging activities have attracted tremendous attention since they can offer both molecular and anatomical information to effectively improve the accuracy of detection. In this work, a β-diketone ligand (CDHH) was modified by covalent conjugation with an MRI contrast agent (DO3A–Gd) and a tumor-targetable biomacromolecule transferrin (Tf). When Eu3+ ions were added into the mixture of two functionalized β-diketone ligands, they triggered a self-assembly to form a heteropolymetallic lanthanide complex that was conjugated to Tf. The as-prepared bioconjugate, i.e., Tf–Eu–Gd, exhibited intense long-lived luminescence (ϕ = 0.20, τ = 0.34 ms), remarkably high MR relaxivities (r1 = 9.18 mM−1 s−1 and r2 = 12.03 mM−1 s−1), as well as good water solubility, stability, and biocompatibility. Time-gated luminescence (TGL) imaging of live cells using Tf–Eu–Gd as a probe demonstrated that the probe can distinguish Tf-receptor-overexpressed cancerous cells, which enables the probe to be specifically accumulated in these cells. On the basis of magnetoluminescent properties of Tf–Eu–Gd, it was further used as a bimodal probe for both TGL and MR imaging of cancerous cells in tumor-bearing nude mice. The results indicated that Tf–Eu–Gd could significantly increase the T1-weighted MRI contrast value in the tumor region, and the TGL imaging of tumor tissue sections provided clear histological validation of the MRI signals. The research outcomes revealed the feasibility of Tf–Eu–Gd for the tracing and precise detection of cancerous cells, which suggested its potential for serving to the clinical diagnosis, therapy, and medical research of tumor diseases.

Background The directional flow of injection through a Whitacre needle can be used to modify the level of sensory blockade. We hypothesized that injection of hyperbaric local anesthetic through a Whitacre needle with the bevel oriented laterally can produce a more symmetric sensory block. Methods Patients scheduled for lower limb surgery under spinal anesthesia with the patient in lateral decubitus position were randomized to receive 10 mg, 0.5% hyperbaric bupivacaine with the Whitacre needle orifice in 1 of 2 orientations, cephalad and lateral. The patient's position was maintained for 15 min after the injection, and sensory blocks were recorded. The primary outcome was the sensory levels between the dependent and nondependent side. The Wilcoxon-Mann-Whitney U-test odds was used to compare unpaired nonparametric data. For the paired samples, 95% confidence intervals (CI) of differences between group medians were calculated using the Hodges-Lehman estimator for the median difference in number of blocked segments. Results There was no significant difference in block level between dependent and nondependent sides in the lateral group. The Hodges-Lehmann point estimator was 0.5% and 95% CI was 0-2.5, suggesting a more symmetric sensory block in patients in the lateral decubitus position maintained for a sufficient period of time. A significantly lower level of blockade was noticed on the nondependent side compared to the dependent side in the cephalad group. The Hodges-Lehmann point estimator was 2.5 segments and 95% CI was 0.5-5. Conclusions Injection of 10 mg of 0.5% hyperbaric bupivacaine with the bevel of the Whitacre needle oriented laterally produces more symmetric sensory levels of blockade between the dependent and nondependent sides.