Successful Development of World's First High-sensitivity Immunochromatographic Test Kit Using Fluorescent Silica Nanoparticle
- Simple and quick test for infectious eye disease (Acanthamoeba keratitis) is realized -

July 9, 2013

Furukawa Electric Co., Ltd. has developed the world's first simplified quick test, resulting from the development of a fluorescent silica nanoparticle (Quartz Dot)(note 1). The nanoparticle has been applied for fluorescent immunochromatographic technology for extracorporeal diagnosis to enable high-sensitivity detection of Acanthamoeba(note 2), a form of bacteria that contributes to eye infection.

In the course of joint clinical research with Prof. Yuichi Ohashi from the Department of Ophthalmology, School of Medicine, Ehime University, this test has been found to be fast (determination is completed within 30 minutes) and also exhibit performance equivalent or superior to conventional incubation-based tests. The achievements will be presented jointly with Ehime University at the 50th Annual Meeting of the Japanese Association for Ocular Infection (Foursome 2013 Osaka) scheduled to begin July 12.

As a materials manufacturer, Furukawa Electric engages in nanoparticle development as part of original material development based on material strength. Among these pursuits, silica nanoparticle shows excellent biocompatibility and stability. Therefore, Furukawa Electric has developed Quartz Dot, its unique nanoparticle that contains fluorescent dye. A simple portable observation device (fluorescent scope) and a quantitative fluorophotometer have also been developed for simplifying and quantifying testing. This has enabled development of a fluorescent immunochromatographic test kit with 100 times the sensitivity of the old immunochromatography. Clinical research accompanying the test confirmed the efficacy.

Currently, a discussion on extracorporeal diagnostics is underway with several diagnostic manufacturers. Making the best of past results, Furukawa Electric will speed up the development to market Quartz Dot at an early stage and offer related products.

Background of development

Quartz Dot consists of fluorescent dye stably fixed inside a nano-sized silica particle, which was developed by combining Furukawa Electric's unique particle synthesis technology and optical technology, and functional groups with connectivity with protein, etc. placed on the particle's surface. Its forte is its broad usage in the life sciences. As the first application of Quartz Dot, Furukawa Electric has undertaken development of high-sensitivity immunochromatography technology, focusing attention on the point-of-care testing (POCT)(note 3) field, in which there is growing demand.

On the other hand, the eye infection field faces an important challenge in that early diagnosis of Acanthamoeba (Ac) keratitis is needed since it has increased with the popularization of contact lenses as an intractable corneal infection. To date, diagnosis of the disease has employed such tests as microscopy of corneal scraping, the incubation method and polymerase chain reaction (PCR) test. However, clinical practice has hoped for a simple and quick test that does not require any advanced skills or special equipment. Conventional immunochromatography based on gold colloid particles also has a problem of poor sensitivity. Under such circumstances, Furukawa Electric set out to develop fluorescent immunochromatography technology boasting high sensitivity and also entered into joint clinical research with Ehime University.

Description of developed product

The developed product takes the same device form as an ordinary immunochromatography kit, consisting of Quartz Dot, a test strip and extracted liquid. To perform a test, a sample treated with extracted liquid and Quartz Dot are mixed, the mixed liquid is delivered by drops at the edge of the test strip, and fluorescent emission is observed with a fluorescent scope for detection.

Overview of test strip

Test kit configuration


(Note 1)Quartz Dot:
Quartz Dot is a fluorescent silica nanoparticle containing a high concentration of organic dye molecules, boasting (1) higher brightness than old fluorescent reagents, (2) no harmful properties, and (3) high hydrophilic property and high compatibility with biological molecules. There are 53 pending patents and 21 registered patents in connection with Quartz Dot.

(Note 2) Acanthamoeba:
Acanthamoeba is a protist living in soil and water. This amoeba may contaminate contact lens preservative solution and containers. Acanthamoeba does not affect healthy people in normal cases, but if the cornea is damaged and a contaminated contact lens is used, the person will be infected and develop Acanthamoeba keratitis. While it progresses very slowly, Acanthamoeba keratitis characteristically causes much more intense pain and still severer congestive symptoms in the white of the eye compared with other eye infections. The initial stages show a low degree of loss of visual acuity and eyesight will gradually weaken. Progression will results in severe visual disability. For a diagnostic test, the affected site of the cornea is scraped to detect Acanthamoeba. It is a problem that this examination is difficult even for large-scale general hospitals. The disease is commonly treated with antifungal drugs since there are no specific remedies for Acanthamoeba. The surface of the affected cornea may at times also need abrading. A complete cure may take several months.

(Note 3)POCT:
POCT is a test that a medical professional performs near a patient. It allows a physician to judge test results quickly, provides a prompt procedure and also monitors treatment process and prognosis. POCT receives particular attention because it is expected to improve the quality of medical examinations.