Biocompatible carbonized iodine-doped dots for contrast-enhanced CT imaging.

BACKGROUND: Computed tomography (CT) imaging has been widely used for the diagnosis and surveillance of diseases. Although CT is attracting attention due to its reasonable price, short scan time, and excellent diagnostic ability, there are severe drawbacks of conventional CT contrast agents, such as low sensitivity, serious toxicity, and complicated synthesis process. Herein, we describe iodine-doped carbon dots (IDC) for enhancing the abilities of CT contrast agents. METHOD: IDC was synthesized by one-pot hydrothermal synthesis for 4 h at 180 ℃ and analysis of its structure and size distribution with UV-Vis, XPS, FT-IR, NMR, TEM, and DLS. Furthermore, the CT values of IDC were calculated and compared with those of conventional CT contrast agents (Iohexol), and the in vitro and in vivo toxicities of IDC were determined to prove their safety. RESULTS: IDC showed improved CT contrast enhancement compared to iohexol. The biocompatibility of the IDC was verified via cytotoxicity tests, hemolysis assays, chemical analysis, and histological analysis. The osmotic pressure of IDC was lower than that of iohexol, resulting in no dilution-induced contrast decrease in plasma. CONCLUSION: Based on these results, the remarkable CT contrast enhancement and biocompatibility of IDC can be used as an effective CT contrast agent for the diagnosis of various diseases compared with conventional CT contrast agents.

Facile Hydrothermal Synthesis of an Iodine-Doped Computed Tomography Contrast Agent Using Insoluble Triiodobenzene.

Carbonized iodine-doped particles (CIPs) were developed to overcome the disadvantages of computed tomography (CT) contrast agents, such as high osmolality and the radiodensity dilution of monomolecular contrast agents and low solubility and high toxicity of polymeric contrast agents. The CIPs were synthesized via a hydrothermal synthesis for 8 h using ATIPA (5-amino-2,4,6-triiodoisophthalic acid), glycerol, and tromethamine in the presence of D.W. (deionized water)-insoluble ATIPA converted into CIPs through a hydrothermal synthesis, showing high solubility and low osmotic pressure. The in vitro contrast effect determined for the resulting CIPs demonstrated a 57.6% enhancement compared to iohexol, and the osmotic pressure of the resulting CIPs was lower than that of iohexol. In addition, the CIPs demonstrated no dilution-induced contrast decrease in plasma and, therefore, demonstrated high contrast strength in vivo. Cytotoxicity tests, hemolysis assays, and histological analyses were conducted to verify the biocompatibility of the CIP product; however, no toxicity was observed. Furthermore, the CIP demonstrated a much higher contrast effect than iohexol at low concentrations. These results indicate that the CIP we have produced may be used as an effective blood pool agent for CT imaging.

Theranostics and contrast agents for magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging is one of the diagnostic tools that uses magnetic particles as contrast agents. It is noninvasive methodology which provides excellent spatial resolution. Although magnetic resonance imaging offers great temporal and spatial resolution and rapid in vivo images acquisition, it is less sensitive than other methodologies for small tissue lesions, molecular activity or cellular activities. Thus, there is a desire to develop contrast agents with higher efficiency. Contrast agents are known to shorten both T1 and T2. Gadolinium based contrast agents are examples of T1 agents and iron oxide contrast agents are examples of T2 agents. In order to develop high relaxivity agents, gadolinium or iron oxide-based contrast agents can be synthesized via conjugation with targeting ligands or functional moiety for specific interaction and achieve accumulation of contrast agents at disease sites. MAIN BODY: This review discusses the principles of magnetic resonance imaging and recent efforts focused on specificity of contrast agents on specific organs such as liver, blood, lymph nodes, atherosclerotic plaque, and tumor. Furthermore, we will discuss the combination of theranostic such as contrast agent and drug, contrast agent and thermal therapy, contrast agent and photodynamic therapy, and neutron capture therapy, which can provide for cancer diagnosis and therapeutics. CONCLUSION: These applications of magnetic resonance contrast agents demonstrate the usefulness of theranostic agents for diagnosis and treatment.

Synthesis of a gadolinium based-macrocyclic MRI contrast agent for effective cancer diagnosis.

BACKGROUND: Gadolinium-based contrast agents are widely used as a contrast agent for magnetic resonance imaging. Since gadolinium ions are toxic, many chelators are developed to bind gadolinium ions to prevent free gadolinium-associated disease. However, many reports indicated that linear chelator-based contrast agents are associated with nephrogenic systemic fibrosis (NSF) in patients with low kidney function. Therefore, the demand for stable macrocyclic chelator-based contrast agent is now increasing. METHOD: 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) was conjugated to lactobionic acid (LBA) through DCC-NHS coupling reaction. Gd3+ (gadolinium ion) was chelated to 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetate-lactobionic acid (DOTA-LAE) and free Gd3+ was removed using a cation exchange column. In vitro cytotoxicity of contrast agent towards normal cells was measured using MTT assay. For in vivo MR imaging, contrast agents were intravenously injected to tumor-bearing mice and imaged by a MR imaging scanner. RESULTS: This new macrocyclic gadolinium-based contrast agent showed enhanced in vitro paramagnetic properties compared to Gadovist. In addition, Gd-DOTA-LAE showed a 29% increased contrast enhancement of tumor tissue compared to normal tissue within 20 min past IV injection. CONCLUSIONS: We developed a new macrocyclic T1-weighted MR contrast agent. This new contrast agent offers various opportunities for cancer detection and diagnosis.

Skin protection efficacy from UV irradiation and skin penetration property of polysaccharide-benzophenone conjugates as a sunscreen agent.

Sunscreen materials have been developed to protect skin from UV radiation. However, many organic sunscreen materials are small molecules and absorbed into human skin after topical application and lead to systemic side effects. To improve the adverse effects of conventional sunscreen materials, we designed a sunscreen agent using an organic sunscreen material and a polymer. Dioxybenzone, an organic sunscreen compound is selected and polymerized with natural polymer pullulan. Polymerization not only provides a long polymer backbone to dioxybenzone, but also keeps the distance between benzene rings of the dioxybenzone and prevents reduction of photoabsorption intensity. UV/vis spectrophotometry confirmed that dioxybenzone-pullulan polymer (DOB-PUL) and dioxybenzone (DOB) demonstrated similar UV absorption. To measure the accumulation of sunscreen materials on skin, Franz diffusion cell was used to confirm the accumulation of DOB and lack of penetration of DOB-PUL. Most importantly, DOB showed higher plasma concentration after multiple applications compared to that of DOB-PUL.

Obstructive uropathy after inguinal herniorrhaphy with a mesh in a renal transplant patient.

A 67-year-old male renal transplant patient presented with a right inguinal bulging mass, and was diagnosed with a right indirect inguinal hernia. The day following inguinal herniorrhaphy, serum creatinine became elevated. The patient was oliguric and had abdominal pain on the first day after inguinal herniorrhaphy with a mesh. We diagnosed him with acute renal failure and subsequently performed acute hemodialysis. The kidney computed tomography showed hydronephroureter, with distal ureter obstruction. With urgent percutaneous nephrostomy, we were able to relieve the obstructive uropathy with distal ureteral stenosis. Subsequently, hernia repair was performed with removal of the mesh, followed by the antegrade ureteral stent insertion. Renal function was recovered after ureteral stent insertion. This case shows that acute renal failure can occur due to ureteral obstruction, complicated by an inguinal hernia repair, and this can be successfully treated with percutaneous nephrostomy and inguinal hernia repair with mesh removal.