Preparation of NIR-II Polymer Nanoprobe Through Twisted Intramolecular Charge Transfer and Förster Resonance Energy Transfer of NIR-I Dye.

Near-infrared-II (NIR-II) fluorescence imaging is pivotal in biomedical research. Organic probes exhibit high potential in clinical translation, due to advantages such as precise structure design, low toxicity, and post-modifications convenience. In related preparation, enhancement of NIR-II tail emission from NIR-I dyes is an efficient method. In particular, the promotion of twisted intramolecular charge transfer (TICT) of relevant NIR-I dyes is a convenient protocol. However, present TICT-type probes still show disadvantages in relatively low emission, large particle sizes, or limited choice of NIR-I dyes, etc. Herein, the synthesis of stable small-sized polymer NIR-II fluoroprobes (e.g., 7.2 nm), integrating TICT and Förster resonance energy transfer process to synergistically enhance the NIR-II emission is reported. Strong enhanced emissions can be obtained from various NIR-I dyes and lanthanide elements (e.g., twelvefold at 1250 nm from Nd-DTPA/IR-808 sample). The fluorophore provides high-resolution angiography, with high-contrast imaging on middle cerebral artery occlusion model mice for distinguishing occlusion. The fluorophore can be rapidly excreted from the kidney (urine ≈65% within 4 h) in normal mice and exhibits long-term renal retention on acute kidney injury mice, showing potential applications in the prognosis of kidney diseases. This development provides an effective strategy to design and synthesize effective NIR-II fluoroprobes.

Contribution of mononuclear bone marrow cells to carbon tetrachloride-induced liver fibrosis in rats.

AIM: To study the inhibitory effect of mononuclear bone marrow cell (BMC) transplantation on carbon tetrachloride (CCl(4)) -induced liver fibrosis in rats. METHODS: Rat liver fibrosis models were induced by CCl(4) and alcohol administration. After 8 wk, twenty rats were randomly allocated into treatment group (n = 10) and control group (n = 10). BMC were infused into the rats in treatment group via the portal vein, while heparinized saline was infused in control group. CCl(4) was hypodermically injected into the rats twice a week for 4 wk. At the end of wk 12, all rats were humanely sacrificed. Liver samples were taken and stained with HE or Masson trichrome. The general conditions, liver fibrosis (hydroxyproline and collagen fibre) and liver pathological grades in rats were evaluated. RESULTS: The general conditions of the rats in treatment group improved markedly, but not in control group. Hydroxyproline was 504.6 +/- 128.8 microg/g in treatment group, and 596.0 +/- 341.8 microg/g in control group. The percentage of collagen fibre was 3.75% +/- 0.98% in treatment group and 5.02% +/- 0.44% in control group. There was a significant difference between the two groups (P < 0.05). Liver pathological grade decreased from grade IV to grade III partially in treatment group (P < 0.05) with no obvious improvement in control group (P > 0.05). There was a significant difference between treatment group and control group (P < 0.05). CONCLUSION: Transplantation of BMC can improve liver fibrosis due to chronic liver injury in rats.