Proteomic analysis of mitochondria associated membranes in renal ischemic reperfusion injury.

BACKGROUND: The mitochondria and endoplasmic reticulum (ER) communicate via contact sites known as mitochondria associated membranes (MAMs). Many important cellular functions such as bioenergetics, mitophagy, apoptosis, and calcium signaling are regulated by MAMs, which are thought to be closely related to ischemic reperfusion injury (IRI). However, there exists a gap in systematic proteomic research addressing the relationship between these cellular processes. METHODS: A 4D label free mass spectrometry-based proteomic analysis of mitochondria associated membranes (MAMs) from the human renal proximal tubular epithelial cell line (HK-2 cells) was conducted under both normal (N) and hypoxia/reperfusion (HR) conditions. Subsequent differential proteins analysis aimed to characterize disease-relevant signaling molecules. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was applied to total proteins and differentially expressed proteins, encompassing Biological Process (BP), Cell Component (CC), Molecular Function (MF), and KEGG pathways. Further, Protein-Protein Interaction Network (PPI) exploration was carried out, leading to the identification of hub genes from differentially expressed proteins. Notably, Mitofusion 2 (MFN2) and BCL2/Adenovirus E1B 19-kDa interacting protein 3(BNIP3) were identified and subsequently validated both in vitro and in vivo. Finally, the impact of MFN2 on MAMs during hypoxia/reoxygenation was explored through regulation of gene expression. Subsequently, a comparative proteomics analysis was conducted between OE-MFN2 and normal HK-2 cells, providing further insights into the underlying mechanisms. RESULTS: A total of 4489 proteins were identified, with 3531 successfully quantified. GO/KEGG analysis revealed that MAM proteins were primarily associated with mitochondrial function and energy metabolism. Differential analysis between the two groups showed that 688 proteins in HR HK-2 cells exhibited significant changes in expression level with P-value < 0.05 and HR/N > 1.5 or HR/N < 0.66 set as the threshold criteria. Enrichment analysis of differentially expressed proteins unveiled biological processes such as mRNA splicing, apoptosis regulation, and cell division, while molecular functions were predominantly associated with energy metabolic activity. These proteins play key roles in the cellular responses during HR, offering insights into the IRI mechanisms and potential therapeutic targets. The validation of hub genes MFN2 and BNIP3 both in vitro and vivo was consistent with the proteomic findings. MFN2 demonstrated a protective role in maintaining the integrity of mitochondria associated membranes (MAMs) and mitigating mitochondrial damage following hypoxia/reoxygenation injury, this protective effect may be associated with the activation of the PI3K/AKT pathway. CONCLUSIONS: The proteins located in mitochondria associated membranes (MAMs) are implicated in crucial roles during renal ischemic reperfusion injury (IRI), with MFN2 playing a pivotal regulatory role in this context.

Terahertz fingerprint reveals the effect of alcohols on sodium ions hydration shell.

Ion hydration plays a crucial role in numerous fundamental processes. Various spectroscopic methods are employed to investigate the slowing down of hydration bond dynamics in the proximity of both anions and cations. To date, most of these studies have primarily focused on the properties of binary systems. However, in comparison to ion-water binary systems, ternary systems that involve ions, water, and organic matter are more prevalent in nature and provide more realistic insights into biological processes. This study focuses on ion hydration in water and alcohol mixture using terahertz spectroscopy and x-ray diffraction (XRD). The results reveal a distinct behavior depending on the type of alcohol used. Specifically, the presence of both methanol and ethanol results in the disappearance of absorption peaks associated with NaCl hydrate at low temperatures. In contrast, tert-butanol does not exhibit such an effect, and isopropanol demonstrates a more complex response. By combining these terahertz spectroscopic findings with low-temperature XRD data, we gain insights into the formation, or lack thereof, of NaCl · 2H2O hydrate crystals. Crucially, our observations suggest a dominant correlation between the polarity of the alcohol molecules and its impact on the Na+ hydration. Strongly polar alcohols preferentially solvating the Na+ ion lead to the failure of hydrate formation, while weakly polar alcohols do not have this effect.

Chromium immobilization from wastewater via iron-modified hydrochar: Different iron fabricants and practicality assessment.

The recycling of industrial solid by-products such as red mud (RM) has become an urgent priority, due to their large quantities and lack of reutilization methods can lead to resource wastage. In this work, RM was employed to fabricate green hydrochar (HC) to prepare zero-valent iron (ZVI) modified carbonous materials, and conventional iron salts (IS, FeCl3) was applied as comparison, fabricated HC labeled as RM/HC and IS/HC, respectively. The physicochemical properties of these HC were comprehensively characterized. Further, hexavalent chromium (Cr(VI)) removal performance was assessed (375.66 and 337.19 mg/g for RM/HC and IS/HC, respectively). The influence of dosage and initial pH were evaluated, while isotherms, kinetics, and thermodynamics analysis were also conducted, to mimic the surface interactions. The stability and recyclability of adsorbents also verified, while the practical feasibility was assessed by bok choy-planting experiment. This work revealed that RM can be used as a high value and green fabricant for HC the effective removal of chromium contaminants from the wastewater.

Which surgical approach is more favorable for pheochromocytoma of different sizes (< 6 cm vs. ≥ 6 cm)? A single retrospective center experience.

BACKGROUND: To compare the surgical effects of lateral transperitoneal approach (LTA) and posterior retroperitoneal approach (PRA) for pheochromocytoma of different sizes. METHODS: Data on patients with pheochromocytoma from 2014 to 2023 were collected from our hospital. According to different surgical approaches and tumor size, all patients were divided into four groups: tumor size < 6 cm for LTA and PRA and tumor size ≥ 6 cm for LTA and PRA. We compared these two surgical methods for pheochromocytoma of different sizes. RESULTS: A total of 118 patients with pheochromocytoma underwent successful laparoscopic surgery, including PRA group (n = 80) and LTA group (n = 38). In tumor size < 6 cm, the outcomes were no significant difference in LTA and PRA. In tumor size ≥ 6 cm, there was a significant difference in operation time (214.7 ± 18.9 vs. 154.3 ± 8.2, P = 0.007) and intraoperative blood loss (616.4 ± 181.3 vs. 201.4 ± 45.8, P = 0.037) between LTA and PRA. CONCLUSION: LTA and PRA were performed safely with similar operative outcomes in patients with pheochromocytoma size < 6 cm. While both LTA and PRA were executed with a commendable safety profile and comparable operative results in patients afflicted by pheochromocytomas < 6 cm, the PRA technique distinctly showcased advantages when addressing large-scale pheochromocytomas (≥ 6 cm). Notably, this manifested in reduced operative time, diminished intraoperative blood loss, decreased hospitalization expenses, and a paucity of procedural complications.

Candy-like heterojunction nanocomposite of WO3/Fe2O3-based semiconductor gas sensor for the detection of triethylamine.

A highly efficient gas sensor for the detection of triethylamine based on candy-like WO3/Fe2O3 nanocomposite was prepared. The control of morphology and sensing performance of n-n heterojunction WO3/Fe2O3 nanocomposites were successfully achieved by the modulation of Fe element content. When the ratio of Fe to W is 0.4, the candy-like nanocomposite of WO3/Fe2O3 with great performance is obtained. It is interesting that the candy-like nanocomposite of WO3/Fe2O3 with a large specific surface area exhibits better selectivity and sensitivity for sensing TEA gases at a lower operating temperature (260 °C) compared with the gas sensor prepared by using WO3 alone. To verify the feasibility, the sensing mechanism was investigated and real sample tests were conducted and discussed. Finally, a TEA gas sensor with low limit of detection, short response/recovery time (15/162 s), and high sensitivity was developed. In addition, the prepared gas sensor has satisfactory stability and selectivity and has practical application value.

Exosomal circLPAR1 functions in colorectal cancer diagnosis and tumorigenesis through suppressing BRD4 via METTL3-eIF3h interaction.

BACKGROUND: Exosomes have emerged as vital biomarkers of multiple cancers and contain abundant circular RNAs (circRNAs). However, the potential for exosomal circRNAs to be used in diagnostics and their molecular mechanism of action in colorectal cancer (CRC) remain unclear. METHODS: CRC-specific exosomal circRNAs were identified by RNA sequencing, exoRBase database and a tissue microarray. The diagnostic performance of plasma exosomal circRNAs was evaluated among cancer-free controls, precancer individuals, CRC patients, and patients with other types of cancer. The corresponding biological functions were mainly assessed using circRNA pull-down, proteomic analysis, and RNA immunoprecipitation assay underlying cellular and mouse models. RESULTS: CircLPAR1 was encapsulated in exosomes with high stability and detectability, and its expression in plasma exosomes was remarkably decreased during CRC development but recovered after surgery. Exosomal circLPAR1 showed cancer specificity in CRC diagnosis and increased the diagnostic performance to an area under the receiver operating characteristic curve of 0.875, as determined by analysing its performance in combination with common clinical biomarkers CEA and CA19-9. Additionally, circLPAR1 was downregulated in CRC tissues and was associated with overall survival. Mechanistically, exosomal circLPAR1 was internalized by CRC cells, and it suppressed tumor growth, likely because exosomal circLPAR1 directly bound with eIF3h specifically suppressed the METTL3-eIF3h interaction, decreasing the translation of oncogene BRD4. CONCLUSIONS: This comprehensive study highlights plasma exosomal circLPAR1 as a promising predictor in CRC diagnosis and describes its biological regulation of colorectal tumorigenesis. This study provides a new perspective on early diagnosis in the clinic and pathogenesis in disease development.

Evaluating the prognostic value of CD56 in pediatric acute myeloid leukemia.

BACKGROUND: Many cytogenetic changes and gene mutations are associated with acute myeloid leukemia (AML) survival outcomes. CD56 is related to poor prognosis when expressed in adult AML patients. However, the prognostic value of CD56 in children with AML has rarely been reported. In this research, we aimed to evaluate the prognostic value of CD56 in childhood AML. METHODS: The present retrospective study included 145 newly diagnosed pediatric patients with de novo AML (excluding AML-M3) in two hospitals between January 2015 and April 2021. RESULTS: The total median (range) age was 75 (8-176) months, and the median follow-up time was 35 months. No significant difference in the 3-year overall survival rate was noted between the CD56-positive and CD56-negative groups (67.0% vs. 79.3%, P = 0.157) who received chemotherapy. However, among high-risk patients, the CD56-positive group had a worse overall survival rate and event-free survival rate (P < 0.05). Furthermore, among high-risk patients, the CD56-positive group had higher relapse and mortality rates than the CD56-negative group (P < 0.05). CONCLUSIONS: CD56 represents a potential factor of poor prognosis in specific groups of children with AML and should be considered in the risk stratification of the disease. Given the independent prognostic value of CD56 expression, we should consider integrating this marker with some immunophenotypic or cytogenetic abnormalities for comprehensive analysis.

miR-874-3p mitigates cisplatin resistance through modulating NF-κB/inhibitor of apoptosis protein signaling pathway in epithelial ovarian cancer cells.

The resistance to cisplatin, the most common platinum chemotherapy drug, may confine the efficacy of treatment in epithelial ovarian cancer patients. Aberrant expression of inhibitor of apoptosis proteins set the stage for resistance to cisplatin in EOC; besides, chemosensitivity in EOC can be chalked up to dysregulation of specific miRNAs. Herein, we investigated whether there is a potential correlation between miR-874-3p and the X-chromosome-linked inhibitor of apoptosis, a member of the IAP protein family in cisplatin-resistant EOC cells. The lower expression of miR-874-3p was found in SKOV3-DDP cells; it was also in association with cisplatin-resistance in EOC cells. XIAP was found to contribute to developing platinum resistance and is an authentic target for miR-874-3p in SKOV3-DDP cells. Consistently, restoration of miR-874-3p expression reversed cisplatin resistance in such cells by modulating XIAP and NF-κB/Survivin signaling pathway. Besides, siRNA knock down of XIAP in SKOV3-DDP cells had an anti-migratory effect like those with miR-874 overexpression. Importantly, the enforced expression of XIAP rescued SKOV3-DDP cells from the cytotoxic effects of miR-874-3p. Finally, miR-874-3p sensitized EOC cells to cisplatin-induced apoptosis, at least in part, through targeting XIAP. The cytotoxic effects of miR-874-3p can be attributed to the targeting XIAP in cisplatin-resistant EOC cells. We believe that the combination of cisplatin with miR-874-3p may make a potential strategy to reverse cisplatin resistance.

Evaluation of the effects of 1,25VitD3 on Th17 cells and Tregs in HTLV-1 infected cell lines.

Human T-lymphotropic virus type 1 (HTLV-1) causes chronic infections of human T lymphocytes. The present study aimed to evaluate the effects of 1,25VitD3 on the proportion of Tregs and Th17 cells, the expression of related transcription factors (ROR-γt and FOXP3) and cytokines (IL-10, TGF-ß, IL-6, and IL-17 A) in the HTLV-1infected cell lines MT-2 and MT-4. MT-2 and MT-4 cells and control PBMCs were treated with 1,25VitD3 and percentages of Tregs and Th17 cells was determined by flow cytometry. Gene expression and cytokine levels were analyzed by real-time PCR and ELISA, respectively. Treatment with-1,25VitD3 increased the percentage of Tregs in MT-2 and MT-4 cells, while it decreased the percentage of Th17 cells among MT-2 cells. 1,25VitD3 treatment also significantly improved FOXP3 gene expression in MT-2 cells, while reducing ROR-γt-gene expression in MT-2 and MT-4 cells comparing to untreated cells. Treatment with 1,25VitD3 significantly improved IL-10 levels in MT-2 cells, as well as TGF-ß levels in both cell lines culture supernatants. 1,25VitD3 treatment diminished IL-6 levels in cell culture supernatants of MT-2 and MT-4 as well as IL-17 A levels in MT-2. Here we showed, that 1,25VitD3 modulated immune responses by enhancing Tregs differentiation and functions as well as inhibiting Th17 differentiation and actions in HTLV-1 infected cell lines. This suggests that VitD3 may have therapeutic effects in HTLV-1-related diseases by suppressing adverse inflammatory responses. Keywords: Tregs; Th17 cells; HTLV-1; 1, 25VitD3.

Near-Field Nanoscopic Terahertz Imaging of Single Proteins.

Terahertz (THz) biological imaging has attracted intense attention due to its capability of acquiring physicochemical information in a label-free, noninvasive, and nonionizing manner. However, extending THz imaging to the single-molecule level remains a challenge, partly due to the weak THz reflectivity of biomolecules with low dielectric constants. Here, the development of graphene-mediated THz scattering-type scanning near-field optical microscope for direct imaging of single proteins is reported. Importantly, it is found that a graphene substrate with high THz reflectivity and atomic flatness can provide high THz contrast against the protein molecules. In addition, a platinum probe with an optimized shaft length is found enabling the enhancement of the amplitude of the scattered THz near-field signals. By coupling these effects, the topographical and THz scattering images of individual immunoglobulin G (IgG) and ferritin molecules with the size of a few nanometers are obtained, simultaneously. The demonstrated strategy thus opens new routes to imaging single biomolecules with THz.

Influence of the PM2.5 Water-Soluble Compound on the Biophysical Properties of A549 Cells.

Understanding the influence of fine atmospheric particles (PM2.5) on cellular biophysical properties is an integral part for comprehending the mechanisms underlying PM2.5-induced diseases because they are closely related to the behaviors and functions of cells. However, hitherto little work has been done in this area. In the present work, we aimed to interrogate the influence of the PM2.5 water-soluble compound (PM2.5-WSC) on the biophysical performance of a human lung carcinoma epithelial cell line (A549) by exploring the cellular morphological and mechanical changes using atomic force microscopy (AFM)-based imaging and nanomechanics. AFM imaging showed that PM2.5-WSC treated cells exhibited evidently reduced lamellipodia and an increased height when compared to the control group. AFM nanomechanical measurements indicated that the treated cells had higher elastic energy and lower adhesion work than the control group. Our western blot assay and transmission electron microscopy (TEM) results revealed that after PM2.5-WSC treatment, the contents of cytoskeletal components (ß-actin and ß-tubulin) increased, but the abundance of cell surface microvilli decreased. The biophysical changes of PM2.5-WSC-treated cells measured by AFM can be well correlated to the alterations of the cytoskeleton and surface microvilli identified by the western blot assay and TEM imaging. The above findings confirm that the adverse risks of PM2.5 on cells can be reliably assessed biophysically by characterizing the cellular morphology and nanomechanics. The demonstrated technique can be used to diminish the gap of our understanding between PM2.5 and its harmful effects on cellular functions.

Measurement of the interconnected turgor pressure and envelope elasticity of live bacterial cells.

Turgor pressure and envelope elasticity of bacterial cells are two mechanical parameters that play a dominant role in cellular deformation, division, and motility. However, a clear understanding of these two properties is lacking because of their strongly interconnected mechanisms. This study established a nanoindentation method to precisely measure the turgor pressure and envelope elasticity of live bacteria. The indentation force-depth curves of Klebsiella pneumoniae bacteria were recorded with atomic force microscopy. Through combination of dimensional analysis and numerical simulations, an explicit expression was derived to decouple the two properties of individual bacteria from the nanoindentation curves. We show that the Young's modulus of bacterial envelope is sensitive to the external osmotic environment, and the turgor pressure is significantly dependent on the external osmotic stress. This method can not only quantify the turgor pressure and envelope elasticity of bacteria, but also help resolve the mechanical behaviors of bacteria in different environments.

Significant association of urinary alpha-1-microglobulin compared to urinary neutrophil gelatinase-associated lipocalin with renal insufficiency in patients with type 2 diabetes.

AIM: Various studies have reported that urinary neutrophil gelatinase-associated lipocalin (NGAL), an indicator of tubular damage, may be an effective biomarker of renal impairment in patients with diabetes. This study aimed to compare the ability of urinary alpha-1-microglobulin (a traditional tubular damage marker) with NGAL for evaluating renal insufficiency in patients with type-2 diabetes. METHODS: Urinary albumin-to-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were used to determine whether 513 participants with type-2 diabetes had renal dysfunction. Urinary alpha-1-microglobulin-to-creatinine ratio (A1MCR) and NGAL-to-creatinine ratio (NCR) were calculated. RESULTS: Although both A1MCR and NCR were significantly higher among participants with renal insufficiency than among participants without renal damage, the difference in A1MCR values between participants with and without renal insufficiency was relatively greater than the difference in NCR values, especially among the male subjects. The correlation of ACR or eGFR with A1MCR was stronger than that of ACR or eGFR with NCR. A1MCR showed a good capability for detecting renal dysfunction (area under the curve = 0.80), its cut-off value was 14.82 mg/g, corresponding to 71.4% sensitivity and 73.1% specificity. The diagnostic efficiency of A1MCR was significantly higher than that of NCR. CONCLUSION: The results indicated that the traditional tubular damage marker A1MCR was more significantly associated with renal insufficiency defined by ACR and/or eGFR and may have a higher diagnostic efficiency compared with the efficiency of NCR in patients with type-2 diabetes.

Clinicopathological features, risk and survival in lung cancer survivors with therapy-related acute myeloid leukaemia.

BACKGROUND: A secondary malignancy is the most serious complication in lung cancer (LC) survivors. This study aimed to evaluate the clinicopathological features, predictable risk factors and survival of patients with LC who developed therapy-related acute myeloid leukaemia (t-AML). METHODS: Patients from the Surveillance, Epidemiology, and End Results (SEER) database diagnosed with t-AML after LC between 1975 and 2015 were included. Standardized incidence ratios (SIRs) were used to perform multiple primary analyses. The risk of t-AML development among LC patients was assessed using a logistic regression model. Kaplan-Meier analysis was used to construct overall survival (OS) curves. Cox regression was used to assess the influence of various prognostic factors. RESULTS: A total of 104 patients with t-AML after LC-targeting chemotherapy were included. The median latency period to the development of t-AML was 35.5 months. The calculated SIR of t-AML was 4.00. Chemoradiotherapy, small cell lung cancer (SCLC), or localized/regional-stage LC was a risk factor for the development of t-AML. The median OS was only 1 month, and those younger than 65 years were predicted to have a better OS time. CONCLUSIONS: t-AML is a rare but serious late complication in LC patients and is associated with a poor prognosis. It is necessary to carry out long-term follow-up and screen for t-AML in LC patients, especially among those undergoing both radiotherapy and chemotherapy, with SCLC or with localized/regional-stage LC.

Clinical application of QuantiFERON-TB Gold in-tube in the diagnosis and treatment of tuberculosis.

At present, although it has made great progress in the diagnosis and treatment of tuberculosis, tuberculosis is still an important cause of morbidity and mortality. There were approximately 8.6 million new cases of tuberculosis in 2012, and approximately 1.3 million people died from tuberculosis. Early diagnosis and timely treatment are essential for controlling the spread of tuberculosis infection and reducing mortality. Conventional methods of Mycobacterium tuberculosis detection such as acid-fast staining microscopy and tuberculin skin test are widely used, but with low sensitivity or specificity. In recent years, a newly developed quantitative test, γ-interferon release test (IGRA), has been recognized and widely applied to the early diagnosis and monitoring of tuberculosis. QuantiFERON-TB Gold in-tube (QFT-GIT) is one of the mature IGRA methods. This paper summarizes the researches on QFT-GIT in recent years and introduces its principles, methodology, clinical application, and factors of uncertain results for the diagnosis and treatment of tuberculosis.

Urinary orosomucoid 1 protein to creatinine ratio as a potential biomarker for early screening of kidney impairment in type-2 diabetes patients.

BACKGROUND: Early screening of diabetic kidney disease (DKD) remains a major challenge. Our aim was to evaluate the value of urinary orosomucoid 1 protein (UORM1) in early renal impairment screening in type-2 diabetes patients. METHODS: The concentration of UORM1, the UORM1-to-creatinine ratio (UORM1CR), the urinary albumin-to-creatinine ratio (ACR), the alpha-1-microglobulin-to-creatinine ratio (A1MCR) and estimated glomerular filtration rate (eGFR) were measured in 406 type-2 diabetes patients. Any positive values for ACR, A1MCR and/or eGFR were considered as indicative of renal impairment. RESULTS: On average, the levels of UORM1 and UORM1CR were about seven times higher in subjects with renal injury than in those without. Both UORM1 and UORM1CR, when adjusted via logarithm-transformation, were significantly related to ACR, A1MCR and eGFR levels. The highest correlation was observed between UORM1CR and A1MCR (r = 0.85, P < .001). The cut-off values for UORM1 (2.53 mg/L) and UORM1CR (3.69 mg/g) for the early diagnosis of kidney impairment were obtained from receiver operating characteristic curves. UORM1CR obviously had higher diagnostic efficiency corresponding to 83.26% sensitivity and 90.32% specificity than UORM1. Likewise, its sensitivity was higher than those of ACR, A1MCR and eGFR. Bad glycaemic control had the highest risk of increased UORM1CR (odds ratio [OR] = 2.81, P < .001), while high HDL-C (high-density lipoprotein cholesterol) decreased the risk of increased UORM1CR (OR = 0.38, P = .017). CONCLUSION: The UORM1CR (>3.69 mg/g) has the high diagnostic efficiency for the early screening of renal impairment in type-2 diabetes patients. Furthermore, good glycaemic control and high HDL-C might be protective factors against UORM1CR increase.

Cross-Category Tea Polyphenols Evaluation Model Based on Feature Fusion of Electronic Nose and Hyperspectral Imagery.

Tea polyphenols are important ingredients for evaluating tea quality. The rapid development of sensors provides an efficient method for nondestructive detection of tea polyphenols. Previous studies have shown that features obtained from single or multiple sensors yield better results in detecting interior tea quality. However, due to their lack of external features, it is difficult to meet the general evaluation model for the quality of the interior and exterior of tea. In addition, some features do not fully reflect the sensor signals of tea for several categories. Therefore, a feature fusion method based on time and frequency domains from electronic nose (E-nose) and hyperspectral imagery (HSI) is proposed to estimate the polyphenol content of tea for cross-category evaluation. The random forest and the gradient boosting decision tree (GBDT) are used to evaluate the feature importance to obtain the optimized features. Three models based on different features for cross-category tea (black tea, green tea, and yellow tea) were compared, including grid support vector regression (Grid-SVR), random forest (RF), and extreme gradient boosting (XGBoost). The results show that the accuracy of fusion features based on the time and frequency domain from the electronic nose and hyperspectral image system is higher than that of the features from single sensor. Whether based on all original features or optimized features, the performance of XGBoost is the best among the three regression algorithms (R2 = 0.998, RMSE = 0.434). Results indicate that the proposed method in this study can improve the estimation accuracy of tea polyphenol content for cross-category evaluation, which provides a technical basis for predicting other components of tea.

Terahertz Spectroscopic Signatures of Microcystin Aptamer Solution Probed with a Microfluidic Chip.

Terahertz signature detection of biological samples in aqueous solution remains a great challenge due to the strong terahertz absorption of water. Here we propose a new preparation process for fabricating a microfluidic chip and use it as an effective sensor to probe the terahertz absorption signatures of microcystin aptamer (a linear single-stranded DNA with 60 nucleotides) dissolved in TE buffer with different concentrations. The microfluidic chip made of silicon includes thousands of 2.4 µm × 2.4 µm square-cross-section channels. One repeatable terahertz absorption signature is detected and recognized around 830 GHz, fitted to a Lorentz oscillator. This signature is theorized to originate from the bending of hydrogen bonds formed between adjacent hydrated DNA bases surrounded by water molecules. Furthermore, the low-lying vibrational modes are also investigated by molecular dynamics simulations which suggest that strong resonant oscillations are highly probable in the 815⁻830 GHz frequency band.

Monitoring cis-to-trans isomerization of azobenzene using terahertz time-domain spectroscopy.

We present terahertz time-domain spectroscopy (THz-TDS) to explore the conformational dynamics of thermally induced and photoinduced isomerization of azobenzene. The essence of the method is that isomerization of azobenzene proceeds via large structural changes in the molecule, while the THz response is sensitive to these changes. We experimentally demonstrate that the THz spectra of azobenzene show remarkable variations upon heating and irradiation, and as such quantitatively recorded and identified THz spectroscopy can be used to monitor the isomerization process. Specifically, the measured THz spectra clearly reveal that the rate of thermal-isomerization from cis-to-trans in non-polar solvents is faster than that in polar solvents, and an about 6-fold acceleration of the rate could be achieved when Au NPs were introduced as a catalyst into azobenzenes. Moreover, we provide evidence that the temperature and Au NP catalyst do not have an obvious influence on the photoinduced isomerization of azobenzene. The presented example illustrates the power of the THz-TDS method to open up a novel avenue for exploring molecular dynamics.

Performance Verification of Alternative Quality Control Materials for Urine Albumin Assessment.

BACKGROUND: Accurate detection of urine albumin is important for evaluating the progression of diabetic kidney disease. However, two levels of daily quality control may not be practically feasible in some small clinical laboratories owing to a small number of patient samples and high costs. We aimed to prepare homemade quality control material (HQM) to measure urine albumin and then verify its performance. METHODS: Normal saline solution and fresh mixed urine samples from five donors with serious kidney disease were used to prepare two levels of HQM (HQM1 and HQM2). Anhydrous ethylene glycol and sodium azide were used as antifreeze and as a preservative, respectively. RESULTS: Before being separated into Eppendorf tubes, 20 tests for HQM1 and HQM2 were performed, resulting in mean ± SD of 19.52 ± 0.91 mg/L and 105.28 ± 3.71 mg/L, respectively. After having been divided, the vial-to-vial variations of HQM1 and HQM2 were small (4.93% and 3.70%, respectively). The stability of HQM1 and HQM2 stored at 2 - 8°C was about 2 months and 80 days, respectively, and when stored at -20°C, remained stable for more than 8 months. After 1 - 8 months of cryopreservation at -20°C, once opened, the HQM in every Eppendorf tube could be kept for at least five days (CV < 6.1%). CONCLUSIONS: Our HQM stored at -20°C remained stable for a long time, and so could be considered as an alternative to standard QMs in the clinical laboratory.