Simultaneous Optical Detection of Multiple Bacterial Species Using Nanometer-Scaled Metal-Organic Hybrids.

This paper describes a simple strategy to identify bacteria using the optical properties of the nanohybrid structures (NHs) of polymer-coated metal nanoparticles (NPs). NHs, in which many small NPs are encapsulated in polyaniline particles, are useful optical labels because they produce strong scattered light. The light-scattering characteristics of NHs are strongly dependent on the constituent metal elements of NPs. Gold NHs (AuNHs), silver NHs (AgNHs), and copper NHs (CuNHs) produce white, reddish, and bluish scattered light, respectively. Moreover, unlike NPs, the color of the scattered light does not change even when NHs are aggregated. Introducing an antibody into NHs induces antigen-specific binding to cells, enabling the identification of bacteria based on light scattering. Multiple bacterial species adsorbed on the slide can be identified within a single field of view under a dark field microscope based on the color of the scattered light. Therefore, it is a useful development for safety risk assessments at manufacturing sites, such as those for foods, beverages, and drugs, and environmental surveys that require rapid detection of multiple bacteria.

Quantification of Enterohemorrhagic Escherichia coli via Optical Nanoantenna and Temperature-responsive Artificial Antibodies.

Enterohemorrhagic Escherichia coli are a dangerous bacterium known to be harmful to the human body, with some infections even resulting in death. Given this danger, food factories are required to perform a quick bacterial test to confirm the absence of this pathogen prior to shipping. We have developed a novel molecular imprinting polymer (MIP) particle that has encapsulated gold nanoparticles (AuNPs) and which can function as both a receptor and an optical signal transmitter in biological systems. This MIP particle is artificially synthesized and can be engineered to specifically recognize and capture antigens on the bacterial cell membrane. In addition, MIP particles containing AuNPs generate strong scattered light signals, and binding of the MIP particles improves the optical intensity of the target bacterial cells. This enables clear visualization under a dark-field microscope and quantification of the target bacteria using the scattering light intensity. Here we describe the successful quantification of Escherichia coli O157 cells in real meat samples using this technology in conjunction with a simple labelling step.

Development of Metal Nanoparticle-immobilized Microplate for High-throughput and Highly Sensitive Fluorescence Analysis.

Enzyme-linked immunosorbent assay (ELISA) is a widespread analytical biochemistry assay. In this work, a direct ELISA method using a metallic nanoparticle (NP)-immobilized 96-well plate was developed for high-throughput, highly sensitive fluorescence analysis. Immobilization of metallic NPs on a 96-well plate effectively amplified fluorescence signals of the assay. The silver (Ag) NP-immobilized plate showed the best fluorescence enhancement effect of all the metal-immobilized plates tested. We used the Ag NP-immobilized plate to detect biomolecules and bacteria and found that both the fluorescence intensity and the limit of detection (LOD) were strongly enhanced by more than 100 times compared with those of the unmodified 96-well plates. Quantitative and qualitative considerations for target bacteria regarding the impact of autofluorescence on detection were successfully obtained for several strains. Our results demonstrate the potential of applying Ag NPs for enhancing the efficiency of direct and indirect ELISA assays.

Fluorescence Enhancement Effect by Metal Nanoparticles-immobilized Microplate.

In this reported work, we achieved high-throughput, highly sensitive fluorescent analysis using an enzyme-linked immunosorbent assay (ELISA) that employed a metallic nanoparticle (NP)-immobilized 96-well plate. The immobilization of metallic NPs on a 96-well plate effectively amplified fluorescent signals of the assay. The silver (Ag) NP-immobilized plate showed the best fluorescent enhancement effect of all plates immobilized by metal NPs. Our results demonstrate the potential of applying Ag NPs to enhance the efficiency of direct and indirect ELISA by the labeling of targets.

Assessing significance of sharpening brand-new scaler.

In order to achieve good clinical results in periodontal treatment, the use of a sharp curette is essential. Many clinicians use curettes immediately after purchase since they assume that brand new curettes have been sharpened. In this study, we aimed to objectively and quantitatively evaluate the sharpness of brand new curette-type scalers, using an experimental apparatus for the detection of the bite force (grab force). As a result of the evaluation of grab force in 120 blades of brand-new curettes, those after sharpening showed an average 12.2% increase in grab force when compared to those without sharpening. Although the grab force of 35 blades showed a decrease (7.3%), 85 blades showed a significant increase (21.7%). These results suggest the importance of sharpening a brand-new scaler before use.

Comparison of clinical practice education in dental hygiene schools in eight countries.

OBJECTIVES: The profession of dental hygienist is one of the few in which the primary function of the practitioner is to prevent oral disease and to promote the well-being of patients. The aim of this study was to investigate clinical training conditions in schools of dental hygiene in eight countries (the USA, Canada, the UK, Sweden, Denmark, Thailand, South Korea and Japan). METHODS: In 2006, we sent out a questionnaire in which we asked dental hygiene schools about how they educate dental hygiene students. RESULTS: The techniques taught to students in schools in Western industrialised nations, such as the USA, Canada, Denmark, the UK and Sweden, were mainly related to dental preventive measures and dental health guidance. By contrast, training schools in South Korea and Japan placed less emphasis on dental preventive measures and dental health guidance. Dental hygienists in Thailand are trained to perform local anaesthesia and to fill and extract deciduous teeth although the country does not have a specific qualification system. CONCLUSIONS: The contents of clinical training and education in schools of dental hygiene differ greatly among countries.