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A novel near infrared fluorescent probe, l-methyl-methionine (Met)–ICG-Der-02, was synthesized and characterized for in vivo imaging of tumors and early diagnosis of cancers. Met was conjugated with ICG-Der-02 dye through the amide bond function by ethyl-3-(3-dimethyllaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide catalysis chemistry. Met–ICG-Der-02 probe uptake was evaluated on PC3, MDA-MB-231, and human embryonic lung fibroblast cell lines. The dynamics of Met–ICG-Der-02 was investigated in athymic nude mice prior to evaluation of the probe targeting capability in prostate and breast cancer models. Met–ICG-Der-02 was successfully synthesized. Cell experiments demonstrated excellent cellular uptake of Met–ICG-Der-02 on cancer cell lines without cytotoxicity. Optical imaging showed a distinguishable fluorescence signal in the tumor area at 2 h while maximal tumor-to-normal tissue contrast ratio was at 12 h Met–ICG-Der-02 post-injection. Additionally, dynamic study of the probe indicated intestinal and liver–kidney clearance pathways. Met–ICG-Der-02 probe is a promising optical imaging agent for tumor diagnosis, especially in their early stage.

Tumor-targeted drug delivery is an attractive strategy in cancer treatment. Our previous study demonstrated that modified adenovirus has strong tumor targeting ability and less toxicity to surrounding normal tissue. In this study, Paclitaxel (PTX), a widely used clinical anticancer drug, was conjugated to folate-modified adenovirus (Ad) nanoparticles by using succinic anhydride and Fmoc-Glu(OtBu)–OH linkers to form two prodrugs, FA-Ad-Suc-PTX and FA-Ad-ICG02-Glu-PTX. Near-infrared (NIR) fluorescent dye ICG-Der-02 was attached to –NH 2 –Glu(OtBu)-PTX for in vivo optical imaging. In vitro and acute toxicity study demonstrates the low toxicity of the prodrug FA-Ad-Suc-PTX and FA-Ad-ICG02-Glu-PTX compared to the free drug. The dynamic behaviors and targeting ability of FA-Ad-ICG02-Glu-PTX on MDA-MB-231 tumor-bearing mice were investigated by NIR fluorescence imaging. The result show that PTX-conjugated Ad vector could enhance the targeting and residence time in tumor site. In vitro and in vivo studies demonstrate that Coxsackie adenovirus receptor (CAR) or foliate receptor (FR)-mediated uptake of FA-Ad-loaded PTX induced highly anti-tumor activity. The results support the potential of using chemically modified Ad vector as drug-loaded tumor-targeting delivery system.

Doxorubicin (DOX) is one of the most effective anti-cancer drugs, but its therapeutic efficacy is greatly hampered by its non-specific delivery to the target tissue and the resultant cumulative cardiotoxicity and nephrotoxicity. In order to overcome this limitation, we prepared a folate-bovine serum albumin (BSA)-cis-aconitic anhydride-doxorubicin prodrug, denoted by FA-BSA-CAD. A tumor-targeting agent, folic acid, was linked to BSA to increase the selective targeting ability of the conjugate. BSA provided a large number of reactive sites for multivalent coupling of bioactive molecules and improved the water-solubility of the prodrug. DOX is attached to the BSA via a pH-sensitive linker, cis-aconitic anhydride, which hydrolyzes in the acidic lysosomal environment to allow pH-responsive release of DOX. The in vitro results demonstrate a pH-responsive drug release under different pH conditions. Furthermore, the targeting ability and therapeutic efficacy of the prodrug were assessed both in vitro and in vivo. The results demonstrate that FA-BSA-CAD prodrug selectively targeted tumor cells and tissue, with associated reduction in non-specific toxicity to the normal cells. More importantly, the therapeutic efficacy of the prodrug for FA-positive tumors increased compared to the non-conjuagted DOX.

Gastrin-releaing peptide(GRP) receptors have over expression distribution on several type of human tumors and less distribution in health tissue. As an GRP analogue, 14 amino acid residues, bombesin has high specificity and affinity to GRPR, this study was about to design, synthesize, and characterize new target specific near infrared(NIR) fluorescent probe based on an 11-amino acid Bombesin analogue, H2N-Gly-Gly-Gly-Gln-Trp-Ala-Val-Gly-His-Leu-Met(NH2). In this study, a near infrared (NIR) fluorescent dyes, ICG-Der-02, was conjugated to BBN analogue to form ICG-Der-02-BBN and ICG-Der-02-PEG-SA-BBN respectively for NIR fluorescent imaging. Probe conjugates were prepared by reation of ICG-Der-02 succinimidyl ester to H2N-Gly-Gly-Gly-Gln-Trp-Ala-Val-Gly-His-Leu-Met(NH2) and ICG-Der-02 succinimidyl ester to PEG4000. The conjugates were purified by HPLC. Confocal fluorescence microscopy images of RhB-BBN and RhB-PEG-SA-BBN in human breast tumor MDA-MB-231 indicated specific uptake in vitro. In addition, the xenografts of MDA-MB-231 cancer cells using ICG-Der-02-BBN and ICG-Der-02-PEG-SA-BBN as near infrared fluorescent probes clearly visualized subcutaneous MDA-MB-231 cancer, also the ability of targeting to gastrin releasing peptide receptor(GRPR) was illustrated. Moreover, after 6h later of inject ICG-Der-02-BBN, high tumor/normal tissue ratios was illustrated by biodistribution experiment. Conclusion: the results suggested that ICG-Der-02-BBN and ICG-Der-02-PEG-SA-BBN were superior probes for in vivo optical imaging.

Cell adhesion molecule integrin αvβ3 is an excellent target for tumor interventions because of its unique expression on the surface of several types of solid tumor cells and on almost all sprouting tumor vasculatures. In this manuscript, we describe the synthesis of near-infrared (NIR) fluorochrome ICG-Der-02-labeled dimeric cyclic RGD peptides (ICG-Der-02-c(RGDyK)2) for in vivo tumor integrin targeting. The optical properties and structure of the probe were intensively characterized. Afterwards, the integrin specificity of the fluorescent probe was tested in vitro for receptor binding assay and fluorescence microscopy and in vivo for subcutaneous MDA-MB-231 and U87MG tumor targeting. The results indicated that after labeling RGD peptide, the optical properties of ICG-Der-02 showed no obvious change. Besides, in vitro and in vivo tumor targeting experiment indicated that the ICG-Der-02-c(RGDyK)2 probe with high integrin affinity showed excellent tumor activity accumulation. Noninvasive NIR fluorescence imaging is able to detect tumor integrin expression based upon the highly potent RGD peptide probe.