Homobifunctional Imidoester Combined Black Phosphorus Nanosheets Used as Cofactors for Nucleic Acid Extraction

Deep Learning Assisted Surface-Enhanced Raman Spectroscopy (SERS) for Rapid and Direct Nucleic Acid Amplification and Detection: Toward Enhanced Molecular Diagnostics

Surface-enhanced Raman scattering (SERS) has evolved into a robust analytical technique capable of detecting a variety of biomolecules despite challenges in securing a reliable Raman signal. Conventional SERS-based nucleic acid detection relies on hybridization assays, but reproducibility and signal strength issues have hindered research on directly amplifying nucleic acids on SERS surfaces. This study introduces a deep learning assisted ZnO-Au-SERS-based direct amplification (ZADA) system for rapid, sensitive molecular diagnostics. The system employs a SERS substrate fabricated by depositing gold on uniformly grown ZnO nanorods. These nanorods create hot spots for the amplification of the target nucleic acids directly on the SERS surface, eliminating the need for postamplification hybridization and Raman reporters. The limit of detection of the ZADA system was superior to those of the conventional amplification methods. Clinical validation of the ZADA system with coronavirus disease 2019 (COVID-19) samples from human patients yielded a sensitivity and specificity of 92.31% and 81.25%, respectively. The integration of a deep learning program further enhanced sensitivity and specificity to 100% and reduced SERS analysis time, showcasing the potential of the ZADA system for rapid, label-free disease diagnosis via direct nucleic acid amplification and detection within 20 min.

Self-directed molecular diagnostics (SdMDx) system for COVID-19 via one-pot processing

Rapid, sensitive, and specific detection of the severe acute respiratory syndrome coronavirus (SARS-CoV)- 2 during early infection is pivotal in controlling the spread and pathological progression of Coronavirus Disease 2019 (COVID-19). Thus, highly accurate, affordable, and scalable point-of-care (POC) diagnostic technologies are necessary. Herein, we developed a rapid and efficient self-directed molecular diagnostic (SdMDx) system for SARS-CoV-2. This system combines the sample preparation step, including virus enrichment and extraction processes, which involve dimethyl suberimidate dihydrochloride and diatomaceous earth functionalized with 3-aminopropyl(diethoxy)methylsilane, and the detection step using loop-mediated isothermal amplification-lateral flow assay (LAMP-LFA). Using the SdMDx system, SARS-CoV-2 could be detected within 47 min by hand without the need for any larger instruments. The SdMDx system enabled detection as low as 0.05 PFU in the culture fluid of SARS-CoV-2-infected VeroE6 cells. We validated the accuracy of the SdMDx system on 38 clinical nasopharyngeal specimens. The clinical utility of the SdMDx system for targeting the S gene of SARS-CoV-2 showed 94.4% sensitivity and 100% specificity. This system is more sensitive than antigen and antibody assays, and it minimizes the use of complicated processes and reduces contamination risks. Accordingly, we demonstrated that the SdMDx system enables a rapid, accurate, simple, efficient, and inexpensive detection of SARS-CoV-2 at home, in emergency facilities, and in low-resource sites as a pre-screening platform and POC testing through self-operation and self-diagnosis.

Multicenter Testing of a Simple Molecular Diagnostic System for the Diagnosis of Mycobacterium Tuberculosis

Mycobacterium tuberculosis (MTB) is a communicable disease and still remains a threat to common health. Thus, early diagnosis and treatment are required to prevent the spread of infection. Despite the recent advances in molecular diagnostic systems, the commonly used MTB diagnostic tools are laboratory-based assays, such as mycobacterial culture, MTB PCR, and Xpert MTB/RIF. To address this limitation, point-of-care testing (POCT)-based molecular diagnostic technologies capable of sensitive and accurate detection even in environments with limited sources are needed. In this study, we propose simple tuberculosis (TB) molecular diagnostic assay by combining sample preparation and DNA-detection steps. The sample preparation is performed using a syringe filter with amine-functionalized diatomaceous earth and homobifunctional imidoester. Subsequently, the target DNA is detected by quantitative PCR (polymerase chain reaction). The results can be obtained within 2 h from samples with large volumes, without any additional instruments. The limit of detection of this system is 10 times higher than those of conventional PCR assays. We validated the clinical utility of the proposed method in 88 sputum samples obtained from four hospitals in the Republic of Korea. Overall, the sensitivity of this system was superior to those of other assays. Therefore, the proposed system can be useful for MTB diagnosis in limited-resource settings.

A novel platform using homobifunctional hydrazide for enrichment and isolation of urinary circulating RNAs

Changes in specific circulating RNA (circRNA) expressions can serve as diagnostic noninvasive biomarkers for prostate cancer (PCa). However, there are still unmet needs, such as unclear types and roles of circRNAs, PCa detection in benign prostatic hyperplasia (BPH) by unstandardized methods, and limitations of sample volume capacity and low circRNA concentrations. This study reports a simple and rapid circRNA enrichment and isolation technique named "HAZIS-CirR" for the analysis of urinary circRNAs. The method utilizes homobifunctional hydrazides with amine-modified zeolite and polyvinylidene fluoride (PVDF) syringe filtration for combining electrostatic and covalent coupling and size-based filtration, and it offers instrument-free isolation of circRNAs in 20 min without volume limitation, thermoregulation, and lysis. HAZIS-CirR has high capture efficiency (82.03%-92.38%) and a 10-fold more sensitive detection limit (20 fM) than before enrichment (200 fM). The clinical utility of HAZIS-CirR is confirmed by analyzing circulating mRNAs and circulating miRNAs in 89 urine samples. Furthermore, three miRNA panels that differentiate PCa from BPH and control, PCa from control, and BPH from control, respectively, are established by comparing miRNA levels. HAZIS-CirR will be used as an optimal and established method for the enrichment and isolation of circRNAs as diagnostic, prognostic, and predictive biomarkers in human cancers.

Laser-Shock-Driven In Situ Evolution of Atomic Defect and Piezoelectricity in Graphitic Carbon Nitride for the Ionization in Mass Spectrometry

Nanostructures─coupled with mass spectrometry─have been intensively investigated to improve the detection sensitivity and reproducibility of small biomolecules in laser desorption/ionization mass spectrometry (LDI-MS). However, the impact of laser-induced shock wave on the ionization of the nanostructures has rarely been reported. Herein, we systematically elucidate the laser shock wave effect on the ionization in terms of the in situ development of atomic defects and piezoelectricity in two-dimensional graphitic carbon nitride nanosheets (g-C₃N₄ NS) by short laser pulses. The mass analysis results of immunosuppressive drugs verify the enhanced LDI-MS performance, structurally originating from anisotropic lattice distortions in g-C₃N₄ NS, i.e., in-plane extension (contraction) and out-of-plane contraction (extension) that modulate the charge carrier motion. Along with the experimental investigations, density functional theory calculations on Mulliken charges and dipole moments demonstrate the contribution of defect and piezoelectricity to the ionization. The results of this study provide a mechanistic understanding of the underlying ionization processes, which is crucial for revealing the full potential of laser shock waves in LDI-MS.

Hot-Spot-Specific Probe (HSSP) for Rapid and Accurate Detection of KRAS Mutations in Colorectal Cancer

Detection of oncogene mutations has significance for early diagnosis, customized treatment, treatment progression, and drug resistance monitoring. Here, we introduce a rapid, sensitive, and specific mutation detection assay based on the hot-spot-specific probe (HSSP), with improved clinical utility compared to conventional technologies. We designed HSSP to recognize KRAS mutations in the DNA of colorectal cancer tissues (HSSP-G12D (GGT→GAT) and HSSP-G13D (GGC→GAC)) by integration with real-time PCR. During the PCR analysis, HSSP attaches to the target mutation sequence for interference with the amplification. Then, we determine the mutation detection efficiency by calculating the difference in the cycle threshold (C_t) values between HSSP-G12D and HSSP-G13D. The limit of detection to detect KRAS mutations (G12D and G13D) was 5–10% of the mutant allele in wild-type populations. This is superior to the conventional methods (≥30% mutant allele). In addition, this technology takes a short time (less than 1.5 h), and the cost of one sample is as low as USD 2. We verified clinical utility using 69 tissue samples from colorectal cancer patients. The clinical sensitivity and specificity of the HSSP assay were higher (84% for G12D and 92% for G13D) compared to the direct sequencing assay (80%). Therefore, HSSP, in combination with real-time PCR, provides a rapid, highly sensitive, specific, and low-cost assay for detecting cancer-related mutations. Compared to the gold standard methods such as NGS, this technique shows the possibility of the field application of rapid mutation detection and may be useful in a variety of applications, such as customized treatment and cancer monitoring.