In Chan Youn

Polymeric Nanoparticle-Based Activatable Near-Infrared Nanosensor for Protease Determination In Vivo

We report here a new protease activatable strategy based on a polymer nanoparticle platform. This nanosensor delivers chemically labeled matrix metalloproteinase (MMP)-activatable fluorogenic peptides to the specific MMPs of interest in vivo. Intravenous administration of the nanosensor in an MMP-positive SCC-7 xenograft tumor and a colon cancer mouse model verified the enzyme specificity of the nanosensor in vivo. The design platform of the nanosensor is flexible and can be fine-tuned for a wide array of applications such as the detection of biomarkers, early diagnosis of disease, and monitoring therapeutic efficacy.

Photo-cured hyaluronic acid-based hydrogels containing simvastatin as a bone tissue regeneration scaffold

We describe in this study the positive influences on in vitro and in vivo osteogenesis of photo-cured hyaluronic acid (HA) hydrogels loaded with simvastatin (SIM). Prior to loading SIM, we first characterized the HA hydrogels for their mechanical properties and swelling ratios. The results from this testing indicated that these two factors improved as the substitution degree of 2-aminoethyl methacrylate (AEMA) increased. MTT and live/dead assays showed that the HA hydrogels have good biocompatibility for use as scaffolds for bone tissue regeneration. Moreover, another MTT assay showed that the photo-cured HA hydrogels III fabricated with 30% AEMA (300 mg) conjugated HA (HA-AEMA iii) loaded with between 0.1 and 1 mg of SIM had a similar cytotoxicity as compared to the HA hydrogel III itself. The sustained release of SIM was observed to occur in the HA hydrogel III loaded with 1 mg of SIM. In vitro and in vivo experiments showed that the HA hydrogel III loaded with 1 mg of SIM had a significant influence on osteogenesis.

Optical imaging of cancer-related proteases using near-infrared fluorescence matrix metalloproteinase-sensitive and cathepsin B-sensitive probes.

Cathepsin B and matrix metalloproteinase (MMP) play key roles in tumor progression by controlled degradation of extracellular matrix. Consequently, these proteases have been attracted in cancer research, and many imaging probes utilizing these proteases have been developed. Our groups developed cathepsin B and MMP imaging nanoprobes based on polymer nanoparticle platform. Both cathepsin B and MMP imaging probes used near-infrared fluorescence (NIRF) dye and dark-quencher to for high sensitivity, and protease-sensitive peptide sequence in each probe authorized high specificity of the probes. We compared the bioactivities of cathepsin B and MMP sensitive probes in cancer-related environments to investigate the biological property of the probes. As a result, cathepsin B probe showed fluorescence recovery after the probe entered the cytoplasm. This property could be useful to evaluate the cytoplasmic targeted delivery by using probe-conjugated nanoparticles in vivo. On the other hand, MMP probe was superior in specificity in vivo and tissue study. This comparative study will provide precise information about peptide-based optical probes, and allow their proper application to cancer diagnosis.

Real time, high resolution video imaging of apoptosis in single cells with a polymeric nanoprobe.

We report a new apoptosis nanoprobe (Apo-NP) designed on the basis of a polymer nanoparticle platform. This simple one-step technique is capable of boosting fluorescence signals upon apoptosis in living cells, enabling real-time imaging of apoptosis in single cells and in vivo. The Apo-NP efficiently delivers chemically labeled, dual-quenched caspase-3-sensitive fluorogenic peptides into cells, allowing caspase-3-dependent strong fluorescence amplification to be imaged in apoptotic cells in real-time and at high resolution. The design platform of the Apo-NP is flexible and can be fine-tuned for a wide array of applications such as identification of caspase-related apoptosis in pathologies and for monitoring therapeutic efficacy of apoptotic drugs in cancer treatment.

A Near-Infrared Fluorescence-Based Optical Thermosensor

A polymeric thermosensor composed of the thermo-responsive block copolymer Pluronic F127 (PF127) and the near-infrared (NIR) dye Cy5.5 can simply monitor, image, and analyze temperature changes. The thermoprobe exhibited linear NIR fluorescent emission changes (see figure) over a broad temperature range (0–80u2009°C).

One-Step Detection of Matrix Metalloproteinase Activity Using a Fluorogenic Peptide Probe-Immobilized Diagnostic Kit

Matrix metalloproteinases (MMPs) have been shown to be abundant in pathological conditions such as cancer, osteoarthritis (OA), and rheumatoid arthritis (RA). The extent of MMPs detected in biological samples provides important clinical information for diagnosis, prognosis, and therapeutic monitoring of various diseases relating with MMPs. Herein, we developed a new high-throughput MMP diagnostic kit (MMP-D-KIT) based on a 96-well plate by immobilizing MMP-13 specific fluorogenic peptide probes (MMP peptide probe), which is a pair consisting of a near-infrared (NIR) fluorophore (Cy5.5) and a quencher (BHQ-3), onto the biocompatible glycol chitosan (GC) polymer anchored 96-well plate. When MMP enzymes were simply added and incubated in a MMP-D-KIT, the fluorescence of each well was recovered and the fluorescence intensity showed distinct difference within minutes through NIR fluorescence imaging system. The fluorescence was recovered not only by MMP-13 activity, but also by other MMPs activity. Furthermore, recovery of NIR fluorescent signals in MMP-D-KIT was proportional to concentrations of immobilized MMP peptide probe-GC conjugates and, importantly, MMP concentration. The MMP-D-KIT is most specific for target MMP, compared with other enzymes including caspase-3 and 20s proteasome. Additionally, the MMP-D-KIT was used to detect MMP activity in biological samples such as synovial fluid from 12 OA patients (grades 1-4 based on the Kellgren-Lawrence grading scale). It was found that the fluorescence intensity measured using MMP-D-KIT decidedly correlates with the progression of OA. The MMP-D-KIT could be applicable in detecting MMP activities in various biological samples and evaluating the effects of MMP inhibitors in a rapid and easy fashion.