A Rapid and High-Throughput Assay for Light Scattering of SARS-CoV-2 Virion-Sized Particulates via Microfluidic Spray Device Reveals the Protection Performance of Face Masks against Virus Infection.

To prevent interhuman transmission of viruses, new mask types─claiming improved filtration─require careful performance characterization. Here, a microfluidic spray device that can effectively simulate droplets emitted during coughing or sneezing was developed to spray droplets containing gold nanoparticles (AuNPs) that mimic SARS-CoV-2 to overcome the shortcomings associated with using biosamples. The light scattered by the AuNPs passing through the mask is successfully analyzed by using an automated scattering light mapping system within a duration of 2 min, thereby enabling high-throughput analysis of the filtering efficiency of various types of commercial masks. The differences in efficiency in terms of same mask type from different manufacturers, double masking, and prolonged usage, which are challenging to analyze with conventional testing systems, can also be assessed. AuNP-mediated mask performance evaluation enables the rapid determination of mask efficiency according to particle size and can contribute to the rapid response to counter new emerging infectious biohazards.

A label-free, ultra-highly sensitive and multiplexed SERS nanoplasmonic biosensor for miRNA detection using a head-flocked gold nanopillar.

Cell-free micro-ribonucleic acids (cf-miRNAs) regulate most human genes by controlling the mRNA translation and have been considered as the most promising biomarkers for cancer diagnosis and prognosis. Due to their low abundance, short length, and similar sequences, an attractive approach that is ultrasensitive and label-free is highly demanded. Herein, we develop a label-free, ultra-high sensitivity and selectivity multiplex miRNA using surface-enhanced Raman scattering to detect cancer-associated miRNAs with head-flocked gold nanopillars as a substrate. Using a complementary DNA probe platform and an ultra-high sensitivity SERS based biosensor, we achieved high selectivity in targeting miRNAs with extremely low detection limits, without any chemical or enzymatic reactions and evaluated the correlation between the miRNA expression level and the Raman signal intensity. A reproducible SERS signal is monitored via uniformly fabricated elastic head-flocked gold nanopillars through a mapping method. This system supports the detection of cell-free miRNAs in blood, which are utilized and quantified as biomarkers to diagnose and provide a prognosis for cancers and intractable diseases. In the foreseeable future, this advanced label-free miRNA detection system is highly promising for a less tumor-invasive biopsy for the early diagnosis and prognosis of cancer.

Tracking of STAT3 signaling for anticancer drug-discovery based on localized surface plasmon resonance.

Signal transducer and activator of transcription 3 (STAT3) protein signaling is crucial for the survival, invasion, and growth of human cancer cells; thus, STAT3 protein is an ideal target for a new drug screening system. Herein, we developed a label-free sensor for anticancer drug-discovery based on the localized surface plasmon resonance (LSPR) shift response by tracking of STAT3 signaling including phosphorylation and dimerization. This enables ultrasensitive monitoring of the molecular interactions that occur on the surface of single gold nanoparticles. The red shift of the LSPR λmax was observed as 3.46 nm and 9.00 nm, respectively, indicating phosphorylation and dimerization of the STAT3 signaling pathway. In screening of anticancer candidates, the system worked well in the presence of STA-21 which inhibits STAT3 dimerization. The LSPR λmax shift in the inhibition condition is three times lower than that in the absence of an inhibitor. Interestingly, the system reveals high specificity, reproducibility and compatibility with real samples (MCF-7 cell line). Therefore, these results demonstrated that this system has strong potential to be an accurate and effective sensor for tracking of signaling pathways and drug screening of anticancer candidates for anticancer therapy.

Distinct plasma phosphorylated-tau proteins profiling for the differential diagnosis of mild cognitive impairment and Alzheimer's disease by plasmonic asymmetric nanobridge-based biosensor.

The differential diagnosis between mild cognitive impairment (MCI) and Alzheimer's disease (AD) has been highly demanded for its effectiveness in preventing and contributing to early diagnosis of AD. To this end, we developed a single plasmonic asymmetric nanobridge (PAN)-based biosensor to differentially diagnose MCI and AD by quantitative profiling of phosphorylated tau proteins (p-tau) in clinical plasma samples, which revealed a significant correlation with AD development and progression. The PAN was designed to have a conductive junction and asymmetric structure, which was unable to be synthesized by the traditional thermodynamical methods. For its unique morphological characteristics, PAN features high electromagnetic field enhancement, enabling the biosensor to achieve high sensitivity, with a limit of detection in the attomolar regime for quantitative analysis of p-tau. By introducing support vector machine (SVM)-based machine learning algorithm, the improved diagnostic system was achieved for prediction of healthy controls, MCI, and AD groups with an accuracy of 94.47 % by detecting various p-tau species levels in human plasma. Thus, our proposed PAN-based plasmonic biosensor has a powerful potential in clinical utility for predicting the onset of AD progression in the asymptomatic phase.

Precise profiling of exosomal biomarkers via programmable curved plasmonic nanoarchitecture-based biosensor for clinical diagnosis of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disease of complex pathogenesis, with overt symptoms following disease progression. Early AD diagnosis is challenging due to the lack of robust biomarkers and limited patient access to diagnostics via neuroimaging and cerebrospinal fluid (CSF) tests. Exosomes present in body fluids are attracting attention as diagnostic biomarkers that directly reflect neuropathological features within the brain. In particular, exosomal miRNAs (exomiRs) signatures are involved in AD pathogenesis, showing a different expression between patients and the healthy controls (HCs). However, low yield and high homologous nature impede the accuracy and reproducibility of exosome blood-based AD diagnostics. Here, we developed a programmable curved plasmonic nanoarchitecture-based biosensor to analyze exomiRs in clinical serum samples for accurate AD diagnosis. To allow the detection of exomiRs in serum at attomolar levels, nanospaces (e.g., nanocrevice and nanocavity) were introduced into the nanostructures to dramatically increase the spectral sensitivity by adjusting the bending angle of the plasmonic nanostructure through sodium chloride concentration control. The developed biosensor classifies individuals into AD, mild cognitive impairment (MCI) patients, and HCs through profiling and quantifying exomiRs. Furthermore, integrating analysis expression patterns of multiple exosomal biomarkers improved serum-based diagnostic performance (average accuracy of 98.22%). Therefore, precise, highly sensitive serum-derived exosomal biomarker detection-based plasmonic biosensor has a robust capacity to predict the molecular pathologic of neurodegenerative disease, progression of cognitive decline, MCI/AD conversion, as well as early diagnosis and treatment.

Detection of multiplex exosomal miRNAs for clinically accurate diagnosis of Alzheimer's disease using label-free plasmonic biosensor based on DNA-Assembled advanced plasmonic architecture.

Alzheimer's disease (AD), the most common neurologic disorder, is characterized by progressive cognitive impairment. However, the low clinical significance of the currently used core AD biomarkers amyloid-beta and tau proteins remains a challenge. Recently, exosomes, found in human biological fluids, are gaining increasing attention because of their clinical significance in diagnosing of various diseases. In particular, blood-derived exosomal miRNAs are not only stable but also provide information regarding the different characteristics according to AD progression. However, quantitative and qualitative detection is difficult due to their characteristics, such as small size, low abundance, and high homology. Here, we present a DNA-assembled advanced plasmonic architecture (DAPA)-based plasmonic biosensor to accurately detect exosomal miRNAs in human serum. The designed nanoarchitecture possesses two narrow nanogaps that induce plasmon coupling; this significantly enhances its optical energy density, resulting in a 1.66-fold higher refractive-index (RI) sensitivity than nanorods at localized surface plasmon resonance (LSPR). Thus, the proposed biosensor is ultrasensitive and capable of selective single-nucleotide detection of exosomal miRNAs at the attomolar level. Furthermore, it identified AD patients from healthy controls by measuring the levels of exosomal miRNA-125b, miRNA-15a, and miRNA-361 in clinical serum samples. In particular, the combination of exosomal miRNA-125b and miRNA-361 showed the best diagnostic performance with a sensitivity of 91.67%, selectivity of 95.00%, and accuracy of 99.52%. These results demonstrate that our sensor can be clinically applied for AD diagnosis and has great potential to revolutionize the field of dementia research and treatment in the future.

A Nanoplasmonic Biosensor for Ultrasensitive Detection of Alzheimer's Disease Biomarker Using a Chaotropic Agent.

Blood-based diagnosis (hemodiagnosis) of Alzheimer's disease (AD) is emerging as a promising alternative to cerebrospinal-fluid-based methods because blood contains various kinds of AD biomarkers, including amyloid beta 1-40, 1-42, and τ (tau) protein. However, with current technology, the accuracy of the blood-plasma-based methods is relatively low compared to the traditional methods because the concentration of AD biomarkers in blood plasma is incredibly low, and diverse interference is present in blood plasma, which hinders precise detection. Here, we suggest a nanoplasmonic biosensor using gold nanorods with a chaotropic agent for precise ultrasensitive detecting of Alzheimer's disease biomarkers in human plasma. This nanoplasmonic biosensor is based on the localized surface plasmon resonance (LSPR), which is extremely sensitive to the point where it can respond to an insignificant change of the refractive index around the gold nanoparticles. Also, using guanidine hydrochloride as a chaotropic agent, we can overcome the obstacles of blood-based AD diagnostics. In more detail, this agent interrupts the network between water molecules and weakens the hydrophobic interactions between proteins, remarkably improving detection capabilities to target τ protein. By reducing the overlapping ranges between protein levels in an age-matched control and AD patients' plasma, this system can accurately diagnose AD patients. This platform also can analyze disease from mild cognitive impairment using standardized blood biomarker tau protein, which is related to Alzheimer's disease. As a result, our platform can be applied to clinical trials, and thus it has excellent potential in the medical field.

Single gold-bridged nanoprobes for identification of single point DNA mutations.

Consensus ranking of protein affinity to identify point mutations has not been established. Therefore, analytical techniques that can detect subtle variations without interfering with native biomolecular interactions are required. Here we report a rapid method to identify point mutations by a single nanoparticle sensing system. DNA-directed gold crystallization forms rod-like nanoparticles with bridges based on structural design. The nanoparticles enhance Rayleigh light scattering, achieving high refractive-index sensitivity, and enable the system to monitor even a small number of protein-DNA binding events without interference. Analysis of the binding affinity can compile an atlas to distinguish the potential of various point mutations recognized by MutS protein. We use the atlas to analyze the presence and type of single point mutations in BRCA1 from samples of human breast and ovarian cancer cell lines. The strategy of synthesis-by-design of plasmonic nanoparticles for sensors enables direct identification of subtle biomolecular binding distortions and genetic alterations.

Enhanced biomass and lipid production of Neochloris oleoabundans under high light conditions by anisotropic nature of light-splitting CaCO3 crystal.

The aim of this work was to study the anisotropic effect of crystalline CaCO3 nanoparticles (CN)-driven multiple refraction/scattering from the CN-coated agglomerated cells on the rate of photosynthesis and the product yield under high light conditions in the freshwater microalgae Neochloris oleoabundans. The CN-coating via biomineralization significantly improved the biomass and lipid production of N. oleoabundans during second stage of autotrophic induction by sustaining relatively high rate of photosynthesis at high irradiance using the multiple-splitting effect of the anisotropic polymorphism. The CN were successfully produced, adsorbed and grown on the external cells under conditions of mild alkalinity (pH 7.5-8.0), mild CaCl2 concentration (0.05 M) and under nitrogen starvation with strong light (400 µE m-2 s-1). Consequently, lipid content and productivity of N. oleoabundans cells cultured with 0.05 M CaCl2 increased by 18.4% and 31.5%, respectively, compared to the cells cultured with 0.05 M CaCl2 and acetazolamide to inhibit calcification.

A shape-code nanoplasmonic biosensor for multiplex detection of Alzheimer's disease biomarkers.

Alzheimer's disease (AD) is a neurodegenerative disease associated with the loss of nerve cells in the brain. The disease is affected by multifactorial pathways and leads to changes in related biomolecular levels as AD progresses. Therefore, AD should be diagnosed with combined detection of several lesions to improve accuracy. Amyloid beta 1-40, 1-42 and τ (tau) protein are milestones in AD pathology and can be used as main screening and diagnostic target markers. Here, we suggest a highly selective biosensor for detection of AD core biomarkers on one platform through distinct localized surface plasmon resonance (LSPR) depending on gold nanoparticles shapes, called a shape-code biosensor. This plasmonic sensor consists of only gold nanoparticles and antibody, but does not need additory methods for precise separation from multifarious samples and identification of markers. Under physiological condition, we determined a detection limit of 34.9fM for amyloid beta (Aß) 1-40, 26fM for Aß 1-42 and 23.6fM for τ protein corresponding to the ~ 1, ~ 2.23 and ~ 3.12nm of Rayleigh scattering peak shift on shape-code plasmon system for each biomarker in mimicked blood. This is the first highly sensitive shape-code biosensor to detect AD biomarkers which can be used to diagnose AD easily in the future.