Hydrogel-based technologies in liquid biopsy for the detection of circulating clinical markers: challenges and prospects

Liquid biopsy, which promises noninvasive detection of tumor-derived material, has recently been highlighted because of its potential to lead us to an era of precision medicine. However, its development has encountered challenges owing to the extremely low frequency and low purity of circulating tumor markers, such as circulating tumor cells (CTCs), circulating exosomes, and circulating tumor nucleic acids (ctNAs). Much effort has been made to overcome this limitation over the last decade, and an increasing number of studies have shown interest in the special characteristics of hydrogels. This hydrophilic and biocompatible polymeric network, which absorbs a large amount of water, can aid in the isolation, protection, and analysis of these low-abundance and short-lived circulating biomarkers. The role of hydrogels in liquid biopsy is extensive and ranges from enrichment to encapsulation. This review provides an overview of hydrogel-based technologies to pave the way in liquid biopsy.

Effect of perioperative "Internet + rehabilitation guidance" based on IKAP theory on short-term prognosis of patients with esophageal cancer

OBJECTIVE

The aim of the study was to investigate the "Internet + rehabilitation guidance" under the theory of Information-Knowledge-Attitude-Practice (IKAP) in patients with esophageal cancer during the perioperative period and to analyze the influence on the short-term prognosis of patients with esophageal cancer.

PATIENTS AND METHODS

From April 2022 to February 2023, 118 patients who underwent radical esophagectomy in the First Hospital of Huai'an Affiliated Hospital of Nanjing Medical University were enrolled using the convenience sampling method. They were divided into the IKAP group (59 cases) and the Control Group (Group C) (59 cases), according to the random number table method. The conventional intervention was performed during the perioperative period, and the IKAP group was also given "Internet + rehabilitation guidance" based on IKAP theory. The first postoperative defecation time, exhaust time, feeding time, discharge time, and postoperative complication rate of the two groups were compared. Meanwhile, blood samples were collected before surgery and 1, 3, 7, and 30 days after surgery (at outpatient review) for the detection of inflammatory factor indexes and nutritional indexes.

RESULTS

Patients within the IKAP group showed a shorter first postoperative exhaust and defecation time, eating time, and hospital compared to the control group (p<0.05). Before surgery, there was no significant difference in serum inflammatory factors and nutritional indexes between the two groups (p>0.05). Comparing the levels of serum inflammatory factors in the two groups after surgery, the levels of CRP and IL-6 in the IKAP group were lower than those in the control group on days 1, 3, and 7 after surgery. After 30 days, the serum CRP level was found to be lower than the control group, but no statistical difference with the control level of serum IL-6 (p<0.05) was found. Compared with the serum nutritional index levels in the two groups: 1 d after surgery, the serum HGB, PA, and TRF levels were not different (p>0.05). The serum ALB level in the IKAP group was higher than that in the control group (p<0.05). Postoperative 3 d, 7 d, the serum levels of HGB, ALB, PA, and TRF in the IKAP group were higher than those in the control group (p<0.05). After 30 d, there was no statistical difference in serum HGB levels between the two groups (p<0.05); Serum ALB, PA, and TRF levels in the IKAP group were higher than those in the control group (p<0.05). From preoperative to 30 days after surgery, serum CRP and IL-6 levels in 2 groups were first increased and then decreased, while serum HGB, ALB, PA, and TRF levels were first decreased and then increased. After surgery, the IKAP group showed a greater incidence of complications in patients than in controls (p<0.05).

CONCLUSIONS

In patients with esophageal cancer, perioperative "Internet + rehabilitation guidance" based on IKAP theory can effectively shorten the postoperative gastrointestinal function recovery time and rapidly reduce the inflammatory response, improving the nutritional status of the body, thereby reducing the risk of short-term postoperative complications.

Advances in nanobiosensors during the COVID-19 pandemic and future perspectives for the post-COVID era

The unprecedented threat of the highly contagious virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes exponentially increased infections of coronavirus disease 2019 (COVID-19), highlights the weak spots of the current diagnostic toolbox. In the midst of catastrophe, nanobiosensors offer a new opportunity as an alternative tool to fill a gap among molecular tests, rapid antigen tests, and serological tests. Nanobiosensors surpass the potential of antigen tests because of their enhanced sensitivity, thus enabling us to see antigens as stable and easy-to-access targets. During the first three years of the COVID-19 pandemic, a substantial number of studies have reported nanobiosensors for the detection of SARS-CoV-2 antigens. The number of articles on nanobiosensors and SARS-CoV-2 exceeds the amount of nanobiosensor research on detecting previous infectious diseases, from influenza to SARS-CoV and MERS-CoV. This unprecedented publishing pace also implies the significance of SARS-CoV-2 and the present pandemic. In this review, 158 studies reporting nanobiosensors for detecting SARS-CoV-2 antigens are collected to discuss the current challenges of nanobiosensors using the criteria of point-of-care (POC) diagnostics along with COVID-specific issues. These advances and lessons during the pandemic pave the way for preparing for the post-COVID era and potential upcoming infectious diseases.

Fast-response electrochemical biosensor based on a truncated aptamer and MXene heterolayer for West Nile virus detection in human serum

West Nile virus (WNV) is a mosquito-borne flavivirus that can cause West Nile fever, meningitis, encephalitis, and polio. Early detection of WNV is important to prevent infection spread on the field. To commercialize the electrochemical biosensor for WNV, rapid target detection with the cheap manufacture cost is essential. Here, we developed a fast-response electrochemical biosensor consisting of a truncated WNV aptamer/MXene (Ti3C2Tx) bilayer on round-type micro gap. To reduce the target binding time, the application of the alternating current electrothermal flow (ACEF) technology reduced the target detection time to within 10 min, providing a rapid biosensor platform. The MXene nanosheet improved electrochemical signal amplification, and the aptamer produced through systematic evolution of ligands by exponential enrichment process eliminated unnecessary base sequences via truncation and lowered the manufacturing cost. Under optimized conditions, the WNV limit of detection (LOD) and selectivity were measured using electrochemical measurement methods, including cyclic voltammetry and square wave voltammetry. The LOD was 2.57 pM for WNV diluted in deionized water and 1.06 pM for WNV diluted in 10% human serum. The fabricated electrochemical biosensor has high selectivity and allows rapid detection, suggesting the possibility of future application in the diagnosis of flaviviridae virus.

Fabrication of graphene oxide-based pretreatment filter and Electrochemical-CRISPR biosensor for the field-ready cyanobacteria monitoring system

Microcystis aeruginosa (M. aeruginosa) cause the eutrophication of lakes and rivers. To effectively control the overgrowth of M. aeruginosa, a suitable measurement method should be required in the aquatic fields. To address this, we developed a field-ready cyanobacterial pretreatment device and an electrochemical clustered regularly interspaced short palindromic repeats (EC-CRISPR) biosensor. The cyanobacterial pretreatment device consists of a syringe, glass bead, and graphene oxide (GO) bead. Then, the M. aeruginosa dissolved in the freshwater sample was added to fabricated filter. After filtration, the purified gene was loaded onto a CRISPR-based electrochemical biosensor chip to detect M. aeruginosa gene fragments. The biosensor was composed of CRISPR/Cpf1 protein conjugated with MXene on an Au microgap electrode (AuMGE) integrated into a printed circuit board (PCB). This AuMGE/PCB system maximizes the signal-to-noise ratio, which controls the working and counter electrode areas requiring only 3 μL samples to obtain high reliability. Using the extracted M. aeruginosa gene with a pre-treatment filter, the CRISPR biosensor showed a limit of detection of 0.089 pg/μl in fresh water. Moreover, selectivity test and matrix condition test carried out using the EC-CRISPR biosensor. These handheld pre-treatment kit and biosensors can enable field-ready detection of CyanoHABs.

Synthesis of Isolated DNA Aptamer and Its Application of AC-Electrothermal Flow-Based Rapid Biosensor for the Detection of Dengue Virus in a Spiked Sample

Dengue fever is an infectious disease caused by the dengue virus (DENV) and is transmitted by mosquitoes in tropical and subtropical regions. The early detection method at a low cost is essential. To address this, we synthesized the isolated DENV aptamer for fabricating a rapid electrochemical biosensor on a Au interdigitated microgap electrode (AuIMGE). The DENV aptamers were generated using the SELEX (systemic evolution of ligands by exponential enrichment) method for binding to DENV surface envelope proteins. To reduce the manufacturing cost, unnecessary nucleotide sequences were excluded from the isolation process of the DENV aptamer. To reduce the detection time, the alternating current electrothermal flow (ACEF) technique was applied to the fabricated biosensor, which can shorten the detection time to 10 min. The performance of the biosensor was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the diluted DENV protein solution, the linear range of the concentrations was from 1 pM to 1 μM and the LOD was 76.7 fM. Moreover, the proposed biosensor detected DENV in a diluted spiked sample at a linear range of 10-6 to 106 TCID50/mL, while the detection performance was proven with an LOD of 1.74 × 10-7 TCID50/mL along with high selectivity.

Electrochemical Detection of Different Foodborne Bacteria for Point-of-Care Applications

Bacterial infections resulting from foodborne pathogenic bacteria cause millions of infections that greatly threaten human health and are one of the leading causes of mortality around the world. To counter this, the early, rapid, and accurate detection of bacterial infections is very important to address serious health issue concerns. We, therefore, present an electrochemical biosensor based on aptamers that selectively bind with the DNA of specific bacteria for the accurate and rapid detection of various foodborne bacteria for the selective determination of bacterial infection types. Different aptamers were synthesized and immobilized on Au electrodes for selective bindings of different types of bacterial DNA (Escherichia coli, Salmonella enterica, and Staphylococcus aureus) for the accurate detection and quantification of bacterial concentrations from 10¹ to 10⁷ CFU/mL without using any labeling methods. Under optimized conditions, the sensor showed a good response to the various concentrations of bacteria, and a robust calibration curve was obtained. The sensor could detect the bacterial concentration at meager quantities and possessed an LOD of 4.2 × 10¹, 6.1 × 10¹, and 4.4 × 10¹ CFU/mL for S. Typhimurium, E. Coli, and S. aureus, respectively, with a linear range from 10⁰ to 10⁴ CFU/mL for the total bacteria probe and 10⁰ to 10³ CFU/mL for individual probes, respectively. The proposed biosensor is simple and rapid and has shown a good response to bacterial DNA detections and thus can be applied in clinical applications and food safety monitoring.

RGO-PANI composite Au microelectrodes for sensitive ECIS analysis of human gastric (MKN-1) cancer cells

Microelectrode-based cell chip studies for cellular responses often require improved adhesion and growth conditions for efficient cellular diagnosis and high throughput screening in drug discovery. Cell-chip studies are often performed on gold electrodes due to their biocompatibility, and stability, but the electrode-electrolyte interfacial capacitance is the main drawback to the overall sensitivity of the detection system. Thus, here, we developed reduced graphene oxide-polyaniline-modified gold microelectrodes for real-time impedance-based monitoring of human gastric adenocarcinoma cancer (MKN-1) cells. The impedance characterization on modified electrodes showed 28-fold enhanced conductivity than the bare electrodes, and the spectra were modeled with proper equivalent circuits to extrapolate the values of circuit elements. The impedance of both time-and frequency-dependent measurements of cell-covered modified electrodes with equivalent model circuits was analyzed to achieve cellular behavior, such as adhesion, spreading, proliferation, and influence of anti-cancer agents. The normalized impedance at 41.5 kHz (|Z|_{norm 41 kHz}) was selected to monitor the cell growth analysis, which was found linear with the proliferation of adherent cells along with the influence of the anticancer drug agent on the MKN-1 cells. The synergistic effects and biocompatible nature of PANI-RGO modifications improved the overall sensitivity for the cell-growth studies of MKN-1 cells.

Nanoparticle-Based Chimeric Antigen Receptor Therapy for Cancer Immunotherapy

Adoptive cell therapy with chimeric antigen receptor (CAR)-engineered T cells (CAR-Ts) has emerged as an innovative immunotherapy for hematological cancer treatment. However, the limited effect on solid tumors, complex processes, and excessive manufacturing costs remain as limitations of CAR-T therapy. Nanotechnology provides an alternative to the conventional CAR-T therapy. Owing to their unique physicochemical properties, nanoparticles can not only serve as a delivery platform for drugs but also target specific cells. Nanoparticle-based CAR therapy can be applied not only to T cells but also to CAR-natural killer and CAR-macrophage, compensating for some of their limitations. This review focuses on the introduction of nanoparticle-based advanced CAR immune cell therapy and future perspectives on immune cell reprogramming.

Rapid electrochemical biosensor composed of DNA probe/iridium nanoparticle bilayer for Aphanizomenon flos-aquae detection in fresh water

Toxic cyanobacteria pose a serious threat to aquatic ecosystems and require adequate detection and control systems. Aphanizomenon flos-aquae is a harmful cyanobacterium that produces the toxicant saxitoxin. Therefore, it is necessary to detect the presence of A. flos-aquae in lakes and rivers. We proposed a rapid electrochemical biosensor composed of DNA primer/iridium nanoparticles (IrNP) bilyer for the detection of A. flos-aquae in freshwater. The extracted A. flos-aquae gene (rbcL-rbcX) is used as a target, and it was fixed to the electrode using a 5'-thiolated DNA primer (capture probe). Then, Avidin@IrNPs complex for amplification of electrical signals was bound to the target through a 3'-biotinylated DNA primer (detection probe). To rapidly detect the target, an alternating current electrothermal flow technique was introduced in the detection step, which could reduce the detection time to within 20 min. To confirm the biosensor fabrication, atomic force microscopy was used to investigate the surface morphology. To evaluate the biosensor performance, cyclic voltammetry and electrochemical impedance spectroscopy were used. The target gene was detected at a concentration of 9.99 pg/mL in tap water, and the detection range was 0.1 ng/mL to 10³ ng/mL with high selectivity. Based on the combined system, we employed A. flos-aquae in tap water. This rapid cyanobacteria detection system is a powerful tool for CyanoHABs in the field.

Impacts of menopause hormone therapy on mood disorders among postmenopausal women

OBJECTIVE

This study aimed to explore the modulatory effects of menopause hormone therapy (MHT) on mood disorders among postmenopausal women.

METHODS

A cross-sectional study was conducted to recruit postmenopausal women, including patients (arranged MHT for over 3 years as the medication group) and non-MHT controls. All participants were asked to respond to the Center for Epidemiological Studies Depression Scale (CES-D) and Generalized Anxiety Disorder Screener (GAD-7) questionnaires to assess their depression and anxiety status.

RESULTS

A total of 230 cases from the two groups were determined based on propensity score matching analysis by matching the menopausal age and menopausal durations. We found that MHT served as a favorable modulator in the depression status of postmenopausal women. Among the four factors of the CES-D questionnaire, our data indicated that the differences between the two groups fell primarily into two aspects: depressive emotion, and somatic symptoms or retarded activities. MHT was mainly involved in improving the depression of overweight women. However, no substantial effects of MHT were observed on the regulation of anxiety.

CONCLUSION

Postmenopausal women, especially the overweight population, who have experienced MHT exhibited an improved depressive status but not their anxiety condition.

Selection of DNA aptamer and its application as an electrical biosensor for Zika virus detection in human serum

Zika virus is a highly infectious virus that is part of the flavivirus group. Precise diagnosis of the Zika virus is significant issue for controlling a global pandemic after the COVID-19 era. For the first time, we describe a zika virus aptamer-based electrical biosensor for detecting Zika virus in human serum. The electrical biosensor composed of a Zika virus aptamer/MXene nanoparticle heterolayer on Au micro-gap electrode (AuMGE)/print circuit board (PCB) system. The Zika virus aptamer was designed to bind the envelope protein of the Zika virus by systematic evolution of ligands by exponential enrichment (SELEX) technique. The binding affinity of the aptamer was determined by fluorescence. For improving the sensor signal sensitivity, Ti₃C₂T_x MXene was introduced to surface of Au micro-gap electrode (AuMGE). The immobilization process was confirmed by atomic force microscopy (AFM). The prepared aptamer/MXene immobilized on AuMGE can detect the Zika virus through capacitance change according to the target concentration. The capacitance signal from the biosensor increased linearly according to increment of envelope proteins in the human serum. The limit of detection was determined to 38.14 pM, and target proteins could be detected from 100 pM to 10 μM. Thus, the developed electrical aptabiosensor can be a useful tool for Zika virus detection.

Rapid, multiplexed, and nucleic acid amplification-free detection of SARS-CoV-2 RNA using an electrochemical biosensor

Considering the worldwide health crisis associated with highly contagious severe respiratory disease of COVID-19 outbreak, the development of multiplexed, simple and rapid diagnostic platforms to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is in high demand. Here, a nucleic acid amplification-free electrochemical biosensor based on four-way junction (4-WJ) hybridization is presented for the detection of SARS-CoV-2. To form a 4-WJ structure, a Universal DNA-Hairpin (UDH) probe is hybridized with two adaptor strands and a SARS-CoV-2 RNA target. One of the adaptor strands is functionalized with a redox mediator that can be detected using an electrochemical biosensor. The biosensor could simultaneously detect 5.0 and 6.8 ag/μL of S and Orf1ab genes, respectively, within 1 h. The biosensor was evaluated with 21 clinical samples (16 positive and 5 negative). The results revealed a satisfactory agreement with qRT-PCR. In conclusion, this biosensor has the potential to be used as an on-site, real-time diagnostic test for COVID-19.

Social Well-Being, Psychological Factors, and Chronic Conditions Among Older Adults

Background

Aging is characterized by the decline in physical health, functional status, and loss of social roles and relationships that can challenge the quality of life. Social well-being may help explain how aging individuals experience declining physical health and social relationships. Despite the high prevalence of chronic conditions among older adults, research exploring the relationship between social well-being and chronic disease is sparse.

Objectives

The study aims were to investigate the relationship between social well-being and psychological factors (e.g., perceived control, life satisfaction, self-esteem, active coping, optimism, and religious coping) by chronic condition in older adults.

Design

Cross-sectional study.

Participants

The current study comprises older adults (N = 1,251, aged ≥ 65 y) who participated in the third wave of the National Survey of Midlife in the United States (i.e., MIDUS).

Setting

MIDUS was conducted on a random-digit-dial sample of community-dwelling, English-speaking adults.

Measurements

Six instruments representing psychological resources (life satisfaction, perceived control, self-esteem, optimism, active coping, and religious coping) and five dimensions of social well-being (social actualization, social coherence, social acceptance, social contribution, social integration) were measured. An index of chronic disease comprised of self-reported data whether they had received a physician's diagnosis for any chronic conditions over the past year.

Results

The findings indicated that the individuals without chronic conditions had significantly higher social integration, social acceptance, and social contribution scores than the individuals with chronic conditions (t = 2.26, p < 0.05, t = 2.85, p < 0.01, and t = 2.23, p < 0.05, respectively). For individuals diagnosed with more than one chronic condition, perceived control, self-esteem, and optimism were positively related to their social well-being (β = .33, p < .001, β = .17, p < .001, and β = .33, p < .001, respectively).

Conclusion

Findings suggested that older adults with multiple chronic conditions have a decrease in social well-being. Chronic disease management programs may help increase social well-being among individuals with multiple chronic conditions.

Improving Biosensors by the Use of Different Nanomaterials: Case Study with Microcystins as Target Analytes

The eutrophication of lakes and rivers without adequate rainfall leads to excessive growth of cyanobacterial harmful algal blooms (CyanoHABs) that produce toxicants, green tides, and unpleasant odors. The rapid growth of CyanoHABs owing to global warming, climate change, and the development of rainforests and dams without considering the environmental concern towards lakes and rivers is a serious issue. Humans and livestock consuming the toxicant-contaminated water that originated from CyanoHABs suffer severe health problems. Among the various toxicants produced by CyanoHABs, microcystins (MCs) are the most harmful. Excess accumulation of MC within living organisms can result in liver failure and hepatocirrhosis, eventually leading to death. Therefore, it is essential to precisely detect MCs in water samples. To date, the liquid chromatography-mass spectrometry (LC-MS) and enzyme-linked immunosorbent assay (ELISA) have been the standard methods for the detection of MC and provide precise results with high reliability. However, these methods require heavy instruments and complicated operation steps that could hamper the portability and field-readiness of the detection system. Therefore, in order for this goal to be achieved, the biosensor has been attracted to a powerful alternative for MC detection. Thus far, several types of MC biosensor have been proposed to detect MC in freshwater sample. The introduction of material is a useful option in order to improve the biosensor performance and construct new types of biosensors. Introducing nanomaterials to the biosensor interface provides new phenomena or enhances the sensitivity. In recent times, different types of nanomaterials, such as metallic, carbon-based, and transition metal dichalcogenide-based nanomaterials, have been developed and used to fabricate biosensors for MC detection. This study reviews the recent advancements in different nanomaterial-based MC biosensors.

Facile and foldable point-of-care biochip for nucleic acid based-colorimetric detection of murine norovirus in fecal samples using G-quadruplex and graphene oxide coated microbeads

Norovirus is one of the most common causes of gastroenteritis, a disease characterized by diarrhea, vomiting, and stomach pain. A rapid on-site identification of the virus from fecal samples of patients is a prerequisite for accurate medical management. Here, we demonstrate a rapid nucleic acid-based detection platform as an on-site biosensing tool that can concentrate viruses from fecal samples. Moreover, it can perform RNA extraction and identification, and signal amplification using G-quadruplex and hemin containing DNA probes (G-DNA probes) and graphene oxide (GO)-coated microbeads. Briefly, murine noroviruses are lysed without chemicals on the surface of the GO microbeads. Subsequently, the target RNA is hybridized with G-DNA probes, and the resultant RNA/G-DNA probe complex is separated from unbound G-DNA probes using GO beads and is mixed with the detection buffer (ABTS/H₂O₂). Presence of murine noroviruses causes a colorimetric change of the buffer from colorless to green. Thus, we integrated all processes required to detect murine noroviruses in stool samples in a simple foldable microfluidic chip. Moreover, it can detect 10¹ pfu of the virus in 30 min in a fecal sample.

Discrimination and isolation of the virus from free RNA fragments for the highly sensitive measurement of SARS-CoV-2 abundance on surfaces using a graphene oxide nano surface

It is highly important to sensitively measure the abundance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on various surfaces. Here, we present a nucleic acid-based detection method consisting of a new sample preparation protocol that isolates only viruses, not the free RNA fragments already present on the surfaces of indoor human-inhabited environments, using a graphene oxide-coated microbead filter. Wet wipes (100 cm2), not cotton swabs, were used to collect viruses from environmental surfaces with large areas, and viruses were concentrated and separated with a graphene oxide-coated microbead filter. Viral RNA from virus was recovered 88.10 ± 8.03% from the surface and free RNA fragment was removed by 99.75 ± 0.19% from the final eluted solution. When we tested the developed method under laboratory conditions, a 10-fold higher viral detection sensitivity (Detection limit: 1 pfu/100 cm2) than the current commercial protocol was observed. Using our new sample preparation protocol, we also confirmed that the virus was effectively removed from surfaces after chemical disinfection; we were unable to measure the disinfection efficiency using the current commercial protocol because it cannot distinguish between viral RNA and free RNA fragments. Finally, we investigated the presence of SARS-CoV-2 and bacteria in 12 individual negative pressure wards in which patients with SARS-CoV-2 infection had been hospitalized. Bacteria (based on 16 S DNA) were found in all samples collected from patient rooms; however, SARS-CoV-2 was mainly detected in rooms shared by two patients.

Mix-and-read, one-minute SARS-CoV-2 diagnostic assay: development of PIFE-based aptasensor

We developed a one-minute, one-step SARS-CoV-2 antigen assay based on protein-induced fluorescence enhancement of a DNA aptamer. The system showed significant selectivity and sensitivity towards both nucleocapsid protein and SARS-CoV-2 virus lysate, but with marked improvements in speed and manufacturability. We hence propose this platform as a mix-and-read testing strategy for SARS-CoV-2 that can be applied to POC diagnostics in clinical settings, especially in low- and middle-income countries.

Fabrication of electrochemical biosensor composed of multi-functional DNA 4 way junction for TNF-α detection in human serum

Tumor necrosis factor (TNF-α) is a representative cytokine family known to induce multiple signaling cascades leading to various cellular responses, such as cell death, survival, and differentiation. It has been reported that blocking the action of TNF-α in various diseases can improve disease prognosis. Therefore, it is important to monitor TNF-α in patient plasma and properly regulate its action. In this study, we report a label-free electrochemical biosensor consisting of a multifunctional DNA 4-way junction (MF-4WJ) for TNF-α detection in human serum. MF-4WJ does not require additional labeling and signal amplification processes. The electrochemical properties of functionalized MF-4WJ were evaluated by cyclic voltammetry (CV) in the presence of Ag⁺ intercalated between the mismatched sequences of MF-aptamers as redox-active species. Afterward, CV was carried out to evaluate the performance of the fabricated biosensor. The proposed label-free electrochemical biosensor was able to effectively detect TNF-α in a dynamic range of 0.15 pg/ml to 150 ng/ml. Limit of detection (LOD) was at 0.07 pg/ml in HEPES. Moreover, it was confirmed that even in 10% diluted human serum, TNF-α could be detected in an excellent dynamic range of 0.15 pg/ml to ∼ 15 ng/ml and LOD was at 0.14 pg/ml in 10% diluted human serum.

Fabrication of a surface-enhanced Raman spectroscopy-based analytical method consisting of multifunctional DNA three-way junction-conjugated porous gold nanoparticles and Au-Te nanoworm for C-reactive protein detection

C-Reactive protein (CRP) is a biomarker of inflammatory responses and an index for assessing the risk of cardiovascular disease and estimating prognosis. In this study, we constructed a surface-enhanced Raman spectroscopy (SERS) biosensor composed of a multifunctional DNA three-way junction (DNA 3WJ), porous gold nanoplates (pAuNPs), and an Au-Te nanoworm structure for detection of CRP. The pAuNP and Au-Te nanostructures were synthesized by galvanic replacement reactions, and the morphology was confirmed by transmission electron microscopy, scanning electron microscopy, and dynamic light scattering (DLS). To generate the SERS signal, the Au-Te nanostructure was immobilized on an indium-tin oxide substrate, and the thiol-modified CRP aptamer was then self-assembled onto the modified substrate for CRP recognition. To amplify the SERS signal and identify the Raman tag, the multifunctional DNA 3WJ was conjugated with the pAuNPs, and each fragment of 3WJ was functionalized to biotin (pAuNP conjugation), methylene blue (Raman reporter), and CRP aptamer (target binding). The results were confirmed by gel electrophoresis. For conjugation between pAuNPs and DNA 3WJ, avidin was encapsulated in pAuNPs, and the conjugation structure was confirmed by DLS. The fabricated SERS biosensor showed detection limits of 2.23 pM in phosphate-buffered saline and 3.11 pM in diluted human serum. Overall, the proposed biosensor may have potential applications as a SERS biosensor platform.

Simple and portable on-site system for nucleic acid-based detection of Clostridium difficile in stool samples using two columns containing microbeads and loop-mediated isothermal amplification

It is challenging to employ nucleic acid-based diagnostics for the in situ detection of Clostridium difficile from complex fecal samples because essential sample preparation and amplification procedures require various experimental resources. In this study, a simple and effective on-site nucleic acid-based detection system was used to detect C. difficile in stool samples. Two columns containing different microbeads, namely, glass and functionalized graphene oxide-coated microbeads, were designed to remove relatively large impurities by filtration and concentrate bacteria, including C. difficile, from stool samples by adsorption. The bacterial nucleic acids were effectively extracted using a small bead beater. The effectiveness of enzyme inhibitors remaining in the sample was efficiently reduced by the direct buffer developed in this study. This sample preparation kit consisting of two simple columns showed better performance in real-time polymerase chain reaction (PCR) and equivalent performance in loop-mediated isothermal amplification (LAMP) than other sample preparation kits, despite 90% simplification of the process. The amplification-ready samples were introduced into two microtubes containing LAMP pre-mixtures (one each for E. coli as an external positive control and C. difficile) by a simple sample loader, which was operated using a syringe. LAMP, which indicates amplification based on color change, was performed at 65 °C in a small water bath. The limit of detection (L.O.D) and analytical sensitivity/specificity of our simple and effective kit were compared with those of a commercial kit. C. difficile in stool samples could be detected within 1 h with 10³ cfu/10 mg using LAMP combined simple on-site detection kit.

Electrospun Nanofibers Embedded with Copper Oxide Nanoparticles to Improve Antiviral Function

Many studies on anti-bacterial/antiviral surfaces have been conducted to prevent epidemic spread worldwide. Several nanoparticles such as those composed of silver and copper are known to have antiviral properties. In this study, we developed copper oxide (CuO) nanoparticle-incorporated nanofibers to inactivate or remove viruses. The CuO nanoparticle-incorporated nanofiber was fabricated with a hydrophobic polymer-polyvinylpyrrolidone (PVP)-using electrospinning, and CuO nanoparticles were exposed from the PVP polymer surface by etching the nanofiber with oxygen plasma. The fabrication conditions of electrospinning and oxygen plasma etching were investigated by scanning electron microscopy (SEM), and field emission transmission electron microscopy (FETEM)/ energy dispersive spectrometry (EDS). H1N1 virus was utilized as the target sample and quantified by RT-qPCR. The antiviral efficacy of CuO nanoparticle-incorporated nanofibers was compared against bare CuO nanoparticles. Overall, 70% of the viruses were inactivated after CuO nanoparticle-incorporated nanofibers were incubated with 10² pfu/mL of H1N1 virus solution for 4 h. This indicates that the developed CuO nanoparticle-incorporated nanofibers have noticeable antiviral efficacy. As the developed CuO nanoparticle-incorporated nanofibers exerted promising antiviral effects against H1N1 virus, it is expected to benefit global health by preventing epidemic spread.

Fabrication of an Electrochemical Aptasensor Composed of Multifunctional DNA Three-Way Junction on Au Microgap Electrode for Interferon Gamma Detection in Human Serum

Interferon gamma (IFN-γ) is an important cytokine with antiviral, antibacterial, and immunosuppressive properties. It has been used as a biomarker for the early detection of several diseases, including cancer, human immunodeficiency virus (HIV), tuberculosis, and paratuberculosis. In this study, we developed an electrochemical biosensor composed of multifunctional DNA 3WJ to detect IFN-γ level with high sensitivity. Each multifunctional triple-stranded aptamer (MF-3WJ) was designed to have an IFN-γ aptamer sequence, anchoring region (thiol group), and 4C-C (cytosine-cytosine) mismatch sequence (signal generation), which could introduce silver ions. To generate the electrochemical signal, four Ag⁺ ions were intercalated (3wj b-3wj c) in the 4C-C mismatch sequence. MF-3WJ was assembled through the annealing step, and the assembly of MF-3WJ was confirmed by 8% tris-boric-EDTA native polyacrylamide gel electrophoresis. The Au microgap electrode was manufactured to load sample volumes of 5 µL. The reliability of electrochemical biosensor measurement was established by enabling the measurement of seven samples from one Au microgap electrode. MF-3WJ was immobilized on the Au microgap electrode. Then, cyclic voltammetry and electrochemical impedance spectroscopy were performed to confirm the electrochemical properties of MF-3WJ. To test the electrochemical biosensor's ability to detect IFN-γ, the limit of detection (LOD) and selectivity tests were performed by square wave voltammetry. A linear region was observed in the concentration range of 1 pg/mL-10 ng/mL of IFN-γ. The LOD of the fabricated electrochemical biosensor was 0.67 pg/mL. In addition, for the clinical test, the LOD test was carried out for IFN-γ diluted in 10% human serum samples in the concentration range of 1 pg/mL-10 ng/mL, and the LOD was obtained at 0.42 pg/mL.

Reasons why patients with tuberculosis in South Korea stop anti-TB treatment: a cross-sectional study

BACKGROUND: As there had been no reduction in the TB burden in South Korea since 2000, a public-private mix (PPM) strategy was launched in 2011. The purpose of this study was to investigate the reasons for lost to follow-up (LTFU) among TB patients and their clinical characteristics.METHOD: A multicentre, cross-sectional study based on in-depth interviews with patients and their families by TB specialist nurses was conducted. Patients who were reported with a final outcome of LTFU in 2015-2017 at all PPM hospitals across the country were enrolled. Enrolled patients were classified into six subgroups by age and three major reasons for LTFU (adverse effects, refusal of treatment, marginalisation) and their clinical features were compared.RESULTS: Among 780 patients, those who were lost to follow-up due to adverse effects accounted for the largest proportion (n = 387). LTFU in those aged <65 years who refused treatment (n = 189) and those aged <65 years who were marginalised (n = 108) were related to having smear-positive TB and a previous history of unfavourable outcomes.CONCLUSION: To reduce LTFU in South Korea, comprehensive strategies, including management of adverse effects, systematic counselling and education, should be implemented.

Suppressed Degradation and Enhanced Performance of CsPbI3 Perovskite Quantum Dot Solar Cells via Engineering of Electron Transport Layers

CsPbI₃ perovskite quantum dots (CsPbI₃-PQDs) have recently come into focus as a light-harvesting material that can act as a platform through which to combine the material advantages of both perovskites and QDs. However, the low cubic-phase stability of CsPbI₃-PQDs in ambient conditions has been recognized as a factor that inhibits device stability. TiO₂ nanoparticles are the most regularly used materials as an electron transport layer (ETL) in CsPbI₃-PQD photovoltaics; however, we found that TiO₂ can facilitate the cubic-phase degradation of CsPbI₃-PQDs due to its vigorous photocatalytic activity. To address these issues, we have developed chloride-passivated SnO₂ QDs (Cl@SnO₂ QDs), which have low photocatalytic activity and few surface traps, to suppress the cubic-phase degradation of CsPbI₃-PQDs. Given these advantages, the CsPbI₃-PQD solar cells based on Cl@SnO₂ ETLs show significantly improved device operational stability (under conditions of 50% relative humidity and 1-sun illumination), compared to those based on TiO₂ ETLs. In addition, the Cl@SnO₂-based devices showed improved open circuit voltage and photocurrent density, resulting in enhanced power conversion efficiency (PCE) up to 14.5% compared to that of TiO₂-based control devices (PCE of 13.8%).

Circulating Tumor Marker Isolation with the Chemically Stable and Instantly Degradable (CSID) Hydrogel ImmunoSpheres

Here, we present chemically stable and instantly degradable (CSID) hydrogel immunospheres for the isolation of circulating tumor cells (CTCs) and circulating tumor exosomes (CTXs). The CSID hydrogels, which are prepared by the hybridization of alginate and poly(vinyl alcohol), show an equilibrium swelling ratio (ESR) of at pH 7, with a highly stable pH-responsive property. The present hybrid hydrogel is not easily disassociated in the biological buffers, thus being suitable for use in "liquid biopsy", requiring a multistep, long-term incubation process with biological samples. Also, it is gradually degraded by the action of chelating agents; effortless retrieval of the circulating markers has been achieved. Then, we modified the CSID hydrogel spheres with the anti-EpCAM antibody ("C-CSID ImmunoSpheres") and the anti-CD63 antibody ("E-CSID ImmunoSpheres") to isolate two promising circulating markers in liquid biopsy: CTCs and CTXs. The immunospheres' capabilities for marker isolation and retrieval were confirmed by a fluorescence image, where the spheres successfully isolate and effortlessly retrieve the target circulating markers. Lastly, we applied the CSID hydrogel immunospheres to five blood samples from colorectal cancer patients and retrieved average 10.8 ± 5.9 CTCs/mL and average 96.5 × 10⁶ CTXs/mL. The present CSID hydrogel immunospheres represent a simple, versatile, and time-efficient assay platform for liquid biopsy in the practical setting, enabling us to gain a better understanding of disease-related circulating markers.

Bacterial Isolation by Adsorption on Graphene Oxide from Large Volume Sample

Graphene oxide (GO) is a well-known two-dimensional nanomaterial with broad applications in various fields. In particular, the functional groups of GO has demonstrated significance in the molecular binding interactions. GO is normally coated on a solid surface as it is difficult to handle due to its nano-scaled size. Therefore, chemical properties of surface-coated GO depend on the morphological structure of GO on the surface and the operating conditions during the coating process. Isolation of bacteria from environmental samples such as river and pond water is important for increasing the analytical sensitivity of sensor devices. The main issue in isolation of bacteria from an environmental sample is adsorption capacity per unit time. However, increasing the velocity of water sample to elevate the process rate induces high shear stress on the surface, such that the bacteria adsorption rate on the surface is reduced. In this study, we investigated the morphological and chemical properties of sonicated GO and GO-coated surface by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The sonicated GO-coated beads were successfully used for concentrating bacteria from a large-volume sample as opposed to the conventional methods. It can be concluded that, GO-coated surfaces are prospective platforms for concentrating bacteria from various samples and play a major role in reducing the concentration time.

Improvement of Heat Sink Effect Using Zinc Oxide Nanostructure

Heat sinks that dissipate heat effectively play a significant role in devices with high-precision temperature control, such as thermal cyclers for polymerase chain reaction (PCR). This study was carried out to develop a heat sink with a high thermal conductivity to dissipate heat effectively. To increase the surface area of the heat sink, zinc oxide (ZnO) nanostructures were fabricated on an aluminum plate. ZnO nanostructures were fabricated by hydrothermal method and confirmed by scanning electron microscopy and X-ray diffraction. With the increase in the concentration of the precursors, the length of the nanorods increased, and with longer reaction time, nanostructures connected with higher stability and larger surface area. Thermal conductivity is increased by ZnO nanostructures and is affected by the concentration of precursors and the reaction time. Thermal conductivity of an optimal ZnO-coated Al plate is 2 times higher than that of a bare one. This technology can be applied to portable PCR devices to reduce weight, size, and power consumption.