Bio-optical Sensor Research Articles

Automated sample-to-answer system for rapid and accurate diagnosis of emerging infectious diseases

Automated sample-to-answer systems that promptly diagnose emerging infectious diseases, such as zoonotic diseases, are crucial to preventing the spread of infectious diseases and future global pandemics. However, automated, rapid, and sensitive diagnostic testing without professionals and sample capacity and type limitations remains unmet needs. Here, we developed an automated sample-to-answer diagnostic system for rapid and accurate detection of emerging infectious diseases from clinical specimens. This integrated system consists of a microfluidic platform for sample preparation and a bio-optical sensor for nucleic acid (NA) amplification/detection. The microfluidic platform concentrates pathogens and NAs in a large sample volume using adipic acid dihydrazide and a low-cost disposable chip. The bio-optical sensor allows label-free, isothermal one-step NA amplification/detection using a ball-lensed optical fiber-based silicon micro-ring resonator sensor. The system is integrated with software to automate testing and perform analysis rapidly and simply; it can distinguish infection status within 80 min. The detection limit of the system (0.96 × 101 PFU) is 10 times more sensitive than conventional methods (0.96 × 102 PFU). Furthermore, we validated the clinical utility of this automated system in various clinical specimens from emerging infectious diseases, including 20 plasma samples for Q fever and 13 (11 nasopharyngeal swabs and 2 saliva) samples for COVID-19. The system showed 100% sensitivity and specificity for detecting 33 samples of emerging infectious diseases, such as Q fever, other febrile diseases, COVID-19, human coronavirus OC43, influenza A, and respiratory syncytial virus A. Therefore, we envision that this automated sample-to-answer diagnostic system will show high potential for diagnosing emerging infectious diseases in various clinical applications.

Rapid Molecular Diagnostic Sensor Based on Ball-Lensed Optical Fibers.

Given the fatal health conditions caused by emerging infectious pathogens, such as severe acute respiratory syndrome coronavirus 2, their rapid diagnosis is required for preventing secondary infections and guiding correct treatments. Although various molecular diagnostic methods based on nucleic acid amplification have been suggested as gold standards for identifying different species, these methods are not suitable for the rapid diagnosis of pathogens owing to their long result acquisition times and complexity. In this study, we developed a rapid bio-optical sensor that uses a ball-lensed optical fiber (BLOF) probe and an automatic analysis platform to precisely diagnose infectious pathogens. The BLOF probe is easy to align and has a high optical sensing sensitivity (1.5-fold) and a large detection range (1.2-fold) for an automatic optical sensing system. Automatic signal processing of up to 250 copies/reaction of DNA of Q-fever-causing Coxiella burnetii was achieved within 8 min. The clinical utility of this system was demonstrated with 18 clinical specimens (9 Q-fever and 9 other febrile disease samples) by measuring the resonant wavelength shift of positive or negative samples for Coxiella burnetii DNA. The results from the system revealed the stable and automatic optical signal measurement of DNA with 100% accuracy. We envision that this BLOF probe-based sensor would be a practical tool for the rapid, simple, and sensitive diagnosis of emerging infectious pathogens.

A novel nucleic acid amplification system based on nano-gap embedded active disk resonators

Recent advances in nucleic acid based testing using bio-optical sensor approaches have been introduced but most are based on hybridization between the optical sensor and the bio-molecule and not on an amplification mechanism. Direct nucleic acid amplification on an optical sensor has several technical limitations, such as the sensitivity of the temperature sensor, instrument complexity, and high background signal. We here describe a novel nucleic acid amplification method based on a whispering gallery mode active resonator and discuss its potential molecular diagnostic application. By implanting nanoclusters as active compounds, this active resonator operates without tapered fiber coupling and emits a strong photoluminescence signal with low background in the wavelength of low absorption in an aqueous environment that is typical of biosensors. Our method also offers an extremely low detection threshold down to a single copy within 10 min due to the strong light-matter interaction in a nano-gap structure. We envision that this active resonator provides a high refractive index contrast for tight mode confinement with simple alignment as well as the possibility of reducing the device size so that a point-of-care system with low-cost, high-sensitivity and simplicity.

Simple and Low-Cost Sampling of Cell-Free Nucleic Acids from Blood Plasma for Rapid and Sensitive Detection of Circulating Tumor DNA.

Cell‐free nucleic acids (cfNAs) are emerging diagnostic biomarkers for monitoring the treatment and recurrence of cancers. In particular, the biological role and clinical usefulness of cfNAs obtained from the plasma of patients with various cancers are popular and still intensely explored, yet most studies are limited by technical problems during cfNA isolation. A dimethyl dithiobispropionimidate (DTBP)‐based microchannel platform that enables spontaneous cfNA capture in 15 min with minimal cellular background and no requirements for use of bulky instruments is reported first. This platform identified KRAS and BRAF hot‐spot mutations following cfDNA isolation from the blood plasma and tissues obtained from 30 colorectal cancer patients. The correlation of mutations between the primary tissues and plasma from the patients was high using this platform with whole genome sequencing compared to the spin‐column method. This platform can also be combined with various detection approaches (biooptical sensor, Sanger sequencing, and polymerase chain reaction (PCR)) for rapid, simple, low‐cost, and sensitive circulating tumor DNA detection in blood plasma. The efficiency and versatility of this platform in isolating cfNAs from liquid biopsies has applications in cancer treatment and precision medicine.

Rapid Diagnosis of Tick-Borne Illnesses by Use of One-Step Isothermal Nucleic Acid Amplification and Bio-Optical Sensor Detection.

Scrub typhus and severe fever with thrombocytopenia syndrome (SFTS) are the most common tick-borne illnesses in South Korea. Early differentiation of SFTS from scrub typhus in emergency departments is essential but difficult because of their overlapping epidemiology, shared risk factors, and similar clinical manifestations. We compared the diagnostic performance of one-step isothermal nucleic acid amplification with bio-optical sensor detection (iNAD) under isothermal conditions, which is rapid (20-30 min), with that of real-time PCR, in patients with a confirmed tick-borne illness. Fifteen patients with confirmed SFTS who provided a total of 15 initial blood samples and 5 follow-up blood samples, and 21 patients with confirmed scrub typhus, were evaluated. The clinical sensitivity of iNAD (100%; 95% CI, 83-100) for SFTS was significantly higher than that of real-time PCR (75%; 95% CI, 51-91; P = 0.047), while its clinical specificity (86%; 95% CI, 65-97) was similar to that of real-time PCR (95%; 95% CI, 77-99; P = 0.61). The clinical sensitivity of iNAD for scrub typhus (100%; 95% CI, 81-100) was significantly higher than that of real-time PCR for scrub typhus (67%; 95% CI, 43-85; P = 0.009), while its clinical specificity (90%; 95% CI, 67-98) was similar to that of real-time PCR (95%; 95% CI, 73-100; P > 0.99). iNAD is a valuable, rapid method of detecting SFTS virus and Orientia tsutsugamushi with high clinical sensitivity and specificity.

A rapid bio-optical sensor for diagnosing Q fever in clinical specimens.

Recent zoonotic outbreaks, such as Zika, Middle East respiratory syndrome and Ebola, have highlighted the need for rapid and accurate diagnostic assays that can be used to aid pathogen control. Q fever is a zoonotic disease caused by the transmission of Coxiella burnetii that can cause serious illness in humans through aerosols and is considered a potential bioterrorism agent. However, the existing assays are not suitable for the detection of this pathogen due to its low levels in real samples. We here describe a rapid bio-optical sensor for the accurate detection of Q fever and validate its clinical utility. By combining a bio-optical sensor, that transduces the presence of the target DNA based on binding-induced changes in the refractive index on the waveguide surface in a label-free and real-time manner, with isothermal DNA amplification, this new diagnostic tool offers a rapid (<20 min), 1-step DNA amplification/detection method. We confirmed the clinical sensitivity (>90%) of the bio-optical sensor by detecting C. burnetii in 11 formalin-fixed, paraffin-embedded liver biopsy samples from acute Q fever hepatitis patients and in 16 blood plasma samples from patients in which Q fever is the cause of fever of unknown origin.

Rapid virus diagnostic system using bio-optical sensor and microfluidic sample processing

Respiratory infection diseases caused by viruses threaten public health worldwide. Although many detection techniques have been developed for virus analysis, they still lack sensitivity, simplicity, and rapidity and require separate sample preparation steps. In this study, we report a virus diagnostic system based on a bio-optical sensor combined with microfluidic sample processing for the rapid and sensitive detection of human adenovirus (HAdV). This system was assembled with a microfluidic-based viral DNA extraction technique and a silicon-based bio-optical sensor for systemically virus extraction and detection. First, viral DNA was obtained from HAdV samples using a novel DNA extraction technique, which is based on the integration of a novel non-chaotropic reagent (dimethyl suberimidate) with a disposable thin-film platform in a single microchannel. This platform can extract viral DNA from clinical samples within 30min and without any instruments. Second, the bio-optical sensor can detect up to 10 copies of HAdV in clinical samples within 30min. Finally, we validated the clinical utility of the virus diagnostic system in 13 human samples, including 10 samples with HAdV and three samples with another pathogen. This virus diagnostic system offers a rapid (<1h) and sensitive (100 times higher than qPCR) diagnostic platform for viral DNA analysis with low cost, simplicity, short assay time, and without the need for complex instruments. Therefore, this system enables the fast diagnosis of viral infection to control the spread of the virus and provide appropriate treatment in the field of respiratory infection diseases.

A single-tube approach for in vitro diagnostics using diatomaceous earth and optical sensor

Versatile, simple and efficient sample preparation is desirable for point-of-care testing of emerging diseases such as zoonoses, but current sample preparation assays are insensitive, labour-intensive and time-consuming and require multiple instruments. We developed a single-tube sample preparation approach involving direct pathogen enrichment and extraction from human specimens using diatomaceous earth (DE). Amine-modified DE was used to directly enrich a zoonotic pathogen, Brucella, in a large sample volume. Next, a complex of amine-modified DE and dimethyl suberimidate was used for nucleic acid extraction from the enriched pathogen. Using our single-tube approach, the pathogen can be enriched and extracted within 60min at a level of 1 colony formation unit (CFU) from a 1ml sample volume in the same tube. The performance of this approach is 10–100 times better than that of a commercial kit (102 to 103CFU/ml) but does not require a large centrifuge. Finally, we combined the single-tube approach with a bio-optical sensor for rapid and accurate zoonotic pathogen detection in human urine samples. Using the combination system, Brucella in human urine can be efficiently enriched (~ 8-fold) and the detection limit is enhanced by up to 100 times (1CFU/ml bacteria in urine) compared with the commercial kit. This combined system is fast and highly sensitive and thus represents a promising approach for disease diagnosis in the clinical setting.

Ultra-low-Light CMOS Biosensor Complements Microfluidics to Achieve Portable Diagnostics

Innovations in ultra low-light CMOS bio-optical sensor design, combined with microfluidics technology can enable a new generation of low cost, portable molecular diagnostics platforms. This combination of technologies have been applied successfully in a miniaturized qPCR system, and a chemiluminescence microfluidic immunoassay platform to detect a variety of infectious pathogens. Cost reduction and miniaturization of molecular test enabled by this technology will have positive impact on global battle against infectious diseases.

An isothermal, label-free, and rapid one-step RNA amplification/detection assay for diagnosis of respiratory viral infections

Recently, RNA viral infections caused by respiratory viruses, such as influenza, parainfluenza, respiratory syncytial virus, coronavirus, and Middle East respiratory syndrome-coronavirus (MERS-CoV), and Zika virus, are a major public health threats in the world. Although myriads of diagnostic methods based on RNA amplification have been developed in the last decades, they continue to lack speed, sensitivity, and specificity for clinical use. A rapid and accurate diagnostic method is needed for appropriate control, including isolation and treatment of the patients. Here, we report an isothermal, label-free, one-step RNA amplification and detection system, termed as iROAD, for the diagnosis of respiratory diseases. It couples a one-step isothermal RNA amplification method and a bio-optical sensor for simultaneous viral RNA amplification/detection in a label-free and real-time manner. The iROAD assay offers a one-step viral RNA amplification/detection example to rapid analysis (<20min). The detection limit of iROAD assay was found to be 10-times more sensitive than that of real-time reverse transcription-PCR method. We confirmed the clinical utility of the iROAD assay by detecting viral RNAs obtained from 63 human respiratory samples. We envision that the iROAD assay will be useful and potentially adaptable for better diagnosis of emerging infectious diseases including respiratory diseases.

The Atlantic Meridional Transect Programme (1995–2012)

The aims of the Atlantic Meridional Transect (AMT) Programme [www.amt-uk.org] are to quantify the nature and causes of ecological and biogeochemical variability in the planktonic ecosystems of the Atlantic Ocean, and to assess the effects of this variability on biological carbon cycling and air–sea exchange of radiatively active gases and aerosols (Fig. 1). Since 1995, marine and atmospheric data have been collected twice a year along a 13,500 km transect between 50°N and 52°S in the Atlantic Ocean. This transect encompasses a range of biogeographical provinces including the subtropical gyres and the equatorial and coastal upwellings. The sampling strategy is described in Robinson et al. (2006a), and for the last six cruises has involved continuous surface seawater and atmospheric sampling, and twice daily deployment of the CTD, bio-optical sensor rig and mesozooplankton nets. Up to 70 determinands were measured on each cruise (see Table 2 in Robinson et al., 2006a). The programme has included 18 research cruises, involving 180 scientists from 11 countries (Fig. 2), contributing to 170 refereed publications and 70 Ph.D. theses. This unique, spatially extensive, decadal dataset continues to be made available to the wider community through the British Oceanographic Data Centre (BODC) (www.bodc.ac.uk).

Spectral characters of Rhodamine B as a multi-information fluorescence probe for bovine serum albumins

The mechanisms of interaction between bovine serum albumin (BSA) with Rhodamine B (RB) have been investigated using fluorescence spectroscopy. The quenching of fluorescence from BSA takes place when increasing the RB concentration. Similar fluorescence quenching from RB also takes place when increasing the BSA concentration. Dual quenching is attributed to the binding of RB to BSA and the energy transfer between BSA and RB. In this interaction, BSA as well as RB acts as both donor and acceptor. Furthermore, increasing the concentration of RB also leads to BSA fluorescence peak splitting at 345 nm. Therefore, not only the intensity, but also shape and peak position of the fluorescence spectrum from BSA are controllable by the concentration of RB. This multi-information fluorescence probe method indicates potential applications in bio-optical sensor.