As a natural polysaccharide polymer, glycogen possesses suitable properties for use as a nanoparticle carrier in cancer theranostics. Not only it is inherently biocompatible, it can also be easily chemically modified with various moieties. Synthetic glycogen conjugates can passively accumulate in tumours due to enhanced permeability of tumour vessels and limited lymphatic drainage (the EPR effect). For this study, we developed and examined a glycogen-based carrier containing a gadolinium chelate and near-infrared fluorescent dye. Our aim was to monitor biodistribution and accumulation in tumour-bearing rats using magnetic resonance and fluorescence imaging. Our data clearly show that these conjugates possess suitable imaging and tumour-targeting properties, and are safe under both in vitro and in vivo conditions. Additional modification of glycogen polymers with poly(2-alkyl-2-oxazolines) led to a reduction in the elimination rate and lower uptake in internal organs (lower whole-body background: 45% and 27% lower MRI signals of oxazoline-based conjugates in the liver and kidneys, respectively compared to the unmodified version). Our results highlight the potential of multimodal glycogen-based nanopolymers as a carrier for drug delivery systems in tumour diagnosis and treatment.

• MeSH
• Glycogen administration & dosage   MeSH
• Rats MeSH
• Drug Delivery Systems * MeSH
• Cell Line, Tumor MeSH
• Neoplasms drug therapy   MeSH
• Antineoplastic Agents administration & dosage   MeSH
• Theranostic Nanomedicine * MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Glycogen MeSH
• Antineoplastic Agents MeSH

The effective drug delivery systems for cancer treatment are currently on high demand. In this paper, biological behavior of the novel hybrid copolymers based on polysaccharide glycogen were characterized. The copolymers were modified by fluorescent dyes for flow cytometry, confocal microscopy, and in vivo fluorescence imaging. Moreover, the effect of oxazoline grafts on degradation rate was examined. Intracellular localization, cytotoxicity, and internalization route of the modified copolymers were examined on HepG2 cell line. Biodistribution of copolymers was addressed by in vivo fluorescence imaging in C57BL/6 mice. Our results indicate biocompatibility, biodegradability, and non-toxicity of the glycogen-based hybrid copolymers. Copolymers were endocyted into the cytoplasm, most probably via caveolae-mediated endocytosis. Higher content of oxazoline in polymers slowed down cellular uptake. No strong colocalization of the glycogen-based probe with lysosomes was observed; thus, it seems that the modified externally administered glycogen is degraded in the same way as an endogenous glycogen. In vivo experiment showed relatively fast biodistribution and biodegradation. In conclusion, this novel nanoprobe offers unique chemical and biological attributes for its use as a novel drug delivery system that might serve as an efficient carrier for cancer therapeutics with multimodal imaging properties.

• Keywords
• Cancer, Contrast agents, Drug delivery, Glycogen, Polymers,
• MeSH
• Hep G2 Cells MeSH
• Endocytosis MeSH
• Fluorescein-5-isothiocyanate administration & dosage   pharmacokinetics   MeSH
• Fluorescent Dyes administration & dosage   pharmacokinetics   MeSH
• Glycogen administration & dosage   pharmacokinetics   MeSH
• Heterocyclic Compounds administration & dosage   pharmacokinetics   MeSH
• Humans MeSH
• Mice, Inbred C57BL MeSH
• Drug Carriers administration & dosage   pharmacokinetics   MeSH
• Organometallic Compounds administration & dosage   pharmacokinetics   MeSH
• Polyamines administration & dosage   pharmacokinetics   MeSH
• Tissue Distribution MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Fluorescein-5-isothiocyanate MeSH
• Fluorescent Dyes MeSH
• gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate MeSH Browser
• Glycogen MeSH
• Heterocyclic Compounds MeSH
• Drug Carriers MeSH
• Organometallic Compounds MeSH
• poly(2-methyl-2-oxazoline) MeSH Browser
• Polyamines MeSH

To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T₁ relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/μL of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe.

• Keywords
• fluorescence lifetime correlation spectroscopy, fluorescence microscopy, high throughput microscopy, magnetic resonance imaging, melanoma brain metastasis, nanoprobe, theranostics, zeta potential,
• MeSH
• Staining and Labeling MeSH
• Cytoplasm metabolism   MeSH
• Spectrometry, Fluorescence MeSH
• Glycogen metabolism   MeSH
• Hydrogen-Ion Concentration MeSH
• Contrast Media chemistry   MeSH
• Humans MeSH
• Lysosomes metabolism   MeSH
• Magnetic Resonance Imaging methods   MeSH
• Melanoma metabolism   pathology   MeSH
• Molecular Probes * MeSH
• Molecular Imaging methods   MeSH
• Multimodal Imaging * MeSH
• Cell Line, Tumor MeSH
• Nanotechnology * MeSH
• Cell Movement MeSH
• Cell Survival MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Glycogen MeSH
• Contrast Media MeSH
• Molecular Probes * MeSH