Prognostic and immunological implications of paraptosis-related genes in lung adenocarcinoma: Comprehensive analysis and functional verification of hub gene

BACKGROUND

Lung adenocarcinoma (LUAD) poses significant clinical challenges due to its inherent heterogeneity and variable response to treatment. Recent research has specifically focused on elucidating the role of Paraptosis-related genes (PRGs) in the progression of cancer and the prognosis of patients.

METHODS

We conducted a comprehensive analysis of the differential expression of PRGs in LUAD. Additionally, univariate Cox regression analysis was utilized to determine the prognostic significance of these genes. Furthermore, consensus clustering was employed to differentiate molecular subtypes within LUAD, while immune heterogeneity was assessed. To evaluate treatment outcomes, the expression of immune checkpoint inhibitors was examined, and the sensitivity of LUAD patients to chemotherapy drugs was assessed. Moreover, machine learning algorithms were employed to construct a Paraptosis-related risk score with prognostic and immunological indicators. Finally, to validate the findings, in vitro experiments were performed to verify the regulatory effect of key PRGs on Paraptosis.

RESULTS

Our analysis identified 24 PRGs that exhibited differential expression, with CDKN3, TP53, and PHB emerging as the most prominently upregulated genes in tumor tissues. Among these genes, seven were identified as prognostic markers, with HSPB8 being the sole protective factor. Notably, our analysis also revealed the existence of two distinct molecular subtypes within LUAD, each characterized by unique prognoses and immune responses. Specifically, Subtype B displayed a poorer prognosis but demonstrated increased sensitivity to both chemotherapy and immunotherapy. In addition, our development of a Paraptosis-Associated Risk Score yielded a significant prognostic value in predicting patient outcomes. Furthermore, we found regulatory effect of CDKN3 on Paraptosis in two cell lines.

CONCLUSIONS

Our study highlights the importance of PRGs in LUAD, particularly in prognosis and treatment response. The identified molecular subtypes and Paraptosis-Associated Risk Score offer valuable insights for personalized treatment strategies.

Dynamic surface reconstruction of individual gold nanoclusters by using a co-reactant enables color-tunable electrochemiluminescence

Here we report for the first time the phenomenon of continuously color-tunable electrochemiluminescence (ECL) from individual gold nanoclusters (Au NCs) confined in a porous hydrogel matrix by adjusting the concentration of the co-reactant. Specifically, the hydrogel-confined Au NCs exhibit strong dual-color ECL in an aqueous solution with triethylamine (TEA) as a co-reactant, with a record-breaking quantum yield of 95%. Unlike previously reported Au NCs, the ECL origin of the hydrogel-confined Au NCs is related to both the Au(0) kernel and the Au(i)-S surface. Surprisingly, the surface-related ECL of Au NCs exhibits a wide color-tunable range of 625-829 nm, but the core-related ECL remains constant at 489 nm. Theoretical and experimental studies demonstrate that the color-tunable ECL is caused by the dynamic surface reconstruction of Au NCs and TEA radicals. This work opens up new avenues for dynamically manipulating the ECL spectra of core-shell emitters in biosensing and imaging research.

Pyrenecarboxaldehyde@Graphene Oxide Acted as a Highly Efficient ECL Emitter and Target-Triggered the Recyclable Cascade System as an Amplifier for Ultrasensitive APE1 Activity Detection

Herein, pyrenecarboxaldehyde@graphene oxide (Pyc@GO) sheets with highly efficient electrochemiluminescence (ECL) as emitters were prepared by a noncovalent combination to develop a neoteric ECL biosensing platform for the ultrasensitive assessment of human apurinic/apyrimidinic endonuclease1 (APE1) activity. Impressively, the pyrenecarboxaldehyde (Pyc) molecules were able to form stable polar functional groups on the surface of GO sheets through the noncovalent π-π stacking mechanism to prevent intermolecular restacking and simultaneously generate Pyc@GO sheets. Compared with the tightly packed PAH nanocrystals, the Pyc@GO sheets significantly reduced internal filtering effects and diminished nonactivated emitters to enhance ECL intensity and achieve strong ECL emission. Furthermore, the APE1-activated initiators could trigger the recyclable cascade amplified system based on the synergistic cross-activation between catalytic hairpin assembly (CHA) and DNAzyme, which improved the signal amplification and transduction ability. Consequently, the developed ECL platform for the detection of APE1 activity displayed exceptional sensitivity with a low detection limit of 4.6 × 10-9 U·mL-1 ranging from 10-8 to 10-2 U·mL-1. Therefore, the proposed strategy holds great promise for the future development of sensitive and reliable biosensing platforms for the detection of various biomarkers.

AND Logic Gate-Regulated DNAzyme Nanoflower for Monitoring the Activity of Multiple DNA Repair Enzymes

Despite the progress that has been made in diverse DNA-based nanodevices to in situ monitor the activity of the DNA repair enzymes in living cells, the significance of improving both the sensitivity and specificity has remained largely neglected and understudied. Herein, we propose a regulatable DNA nanodevice to specifically monitor the activity of DNA repair enzymes for early evaluation of cancer mediated by genomic instability. Concretely, an AND logic gate-regulated DNAzyme nanoflower was rationally designed by the self-assembly of the DNA duplex modified with both apurinic/apyrimidinic (AP) site and methyl lesion site. The DNAzyme nanoflower could be reconfigured under the repair of AP sites and O6-methylguanine sites by apurinic/apyrimidinic endonuclease 1 (APE1) and O6-methylguanine methyltransferase (MGMT) to produce a fluorescent signal, realizing the sensitive monitoring of the activity of APE1 and MGMT. Compared to the free DNAzyme duplex, the fluorescent response of the DNAzyme nanoflower increased by 60%, due to the effective enrichment of the DNA probes by the nanoflower structure. More importantly, we have demonstrated that the dual-enzyme activated strategy allows imaging of specific cancer cells in the AND logic gate manner using MCF-7 as a cancer cell model, improving the specificity of cancer cell imaging. This AND logic gate-regulated multifunctional DNAzyme nanoflower provides a simple tool for simultaneously visualizing multiple DNA repair enzymes, holding great potential in early clinical diagnosis and drug discovery.

Universal Signal Switch Based on a Mesostructured Silica Xerogel-Confined ECL Polymer for Epigenetic Quantification

The development of a highly accurate electrochemiluminescence (ECL) signal switch to avoid nonspecific stimulus responses is currently a significant and challenging task. Here, we constructed a universal signal switch utilizing a luminophore-quencher pair of mesostructured silica xerogel-confined polymer and gold nanoparticles (Au NPs) that can accurately detect low-abundance epigenetic markers in complex sample systems. Notably, the ECL polymer encapsulated in mesostructured silica xerogel acts as a luminophore, which demonstrated a highly specific dependence on the Au NPs-mediated energy transfer quenching. To demonstrate the feasibility, we specifically labeled the 5-hydroxymethylcytosine (5hmC) site on the random sequence using a double-stranded (dsDNA) tag that was skillfully designed with the CRISPR/Cas12a activator and recombinant polymerase amplification (RPA) template. After amplification by RPA, a large amount of dsDNA tag was generated as the activator to initiate the trans-cleavage activity of CRISPR/Cas12a and subsequently activate the signal switch, allowing for precise quantification of 5hmC. The ECL signal switch improves the stability of the luminophore and prevents nonspecific stimulus responses, providing a new paradigm for constructing high-precision biosensors.

Circular DNAzyme-Switched CRISPR/Cas12a Assay for Electrochemiluminescent Response of Demethylase Activity

DNA nanostructure provides powerful tools for DNA demethylase activity detection, but its stability has been significantly challenged. By virtue of circular DNA with resistance to exonuclease degradation, herein, the circular DNAzyme duplex with artificial methylated modification was constructed to identify the target and output the DNA activators to drive the CRISPR/Cas12a, constructing an "on-off-on" electrochemiluminescence (ECL) biosensor for monitoring the activity of the O6-methylguanine-DNA methyltransferase (MGMT). Specifically, the circular DNAzyme duplex consisted of the chimeric RNA-DNA substrate ring with double activator sequences and two single-stranded DNAzymes, whose catalytic domains were premodified with the methyl groups. When the MGMT was present, the methylated DNAzymes were repaired and restored the catalytic activity to cleave the chimeric RNA-DNA substrates, followed by the output of DNA activators to initiate the CRISPR/Cas12a. Subsequently, the ECL signals of silver nanoparticle-modified SnO2 nanospheres (Ag@SnO2) were recovered by releasing the ferrocene-labeled quenching probes (Fc-DNA) from the electrode surface because of the trans-cleavage activity of CRISPR/Cas12a, thus achieving the specific and sensitive ECL detection of MGMT from 2.5 × 10-4 to 2.5 × 102 ng/mL with a low limit (9.69 × 10-5 ng/mL). This strategy affords novel ideas and insights into research on how to project stable nucleic acid probes to detect DNA demethylases beyond traditional methods.

Procalcitonin and C-reactive protein as diagnostic biomarkers in COVID-19 and Non-COVID-19 sepsis patients: a comparative study

BACKGROUND

This study aimed to assess and compare procalcitonin (PCT) and C-reactive protein (CRP) levels between COVID-19 and non-COVID-19 sepsis patients. Additionally, we evaluated the diagnostic efficiency of PCT and CRP in distinguishing between Gram-positive (GP) and Gram-negative (GN) bacterial infections. Moreover, we explored the associations of PCT with specific pathogens in this context.

METHODS

The study included 121 consecutive sepsis patients who underwent blood culture testing during the COVID-19 epidemic. PCT and CRP were measured, and reverse transcriptase-polymerase chain reaction (RT-PCR) was employed for the detection of COVID-19 nucleic acid. The Mann-Whitney U-test was used to compare PCT and CRP between the COVID-19 and non-COVID-19 groups. Receiver operating characteristic (ROC) curves were generated to compare PCT and CRP levels in the GN group versus the GP group for assessing the diagnostic efficiency. The kruskal-Wallis H test was applied to assess the impact of specific pathogen groups on PCT concentrations.

RESULTS

A total of 121 sepsis patients were categorized into a COVID-19 group (n = 25) and a non-COVID-19 group (n = 96). No significant differences in age and gender were observed between the COVID-19 and non-COVID-19 groups. The comparison of biomarkers between these groups showed no statistically significant differences. The optimal cut-off values for PCT and CRP in differentiating between GP and GN infections were 1.03 ng/mL and 34.02 mg/L, respectively. The area under the ROC curve was 0.689 (95% confidence interval (CI) 0.591-0.786) for PCT and 0.611 (95% CI 0.505-0.717) for CRP. The diagnostic accuracy was 69.42% for PCT and 58.69% for CRP. The study found a significant difference in PCT levels among specific groups of pathogens (P < 0.001), with the highest levels observed in Escherichia coli infections. The frequency of Staphylococcus spp. positive results was significantly higher (36.0%) in COVID-19 compared to non-COVID-19 sepsis patients (P = 0.047).

CONCLUSION

Sepsis patients with COVID-19 revealed a significantly higher culture positivity for staphylococcus spp. than the non-COVID-19 group. Both PCT and CRP showed moderate diagnostic efficiency in differentiating between GP and GN bacterial infections. PCT showed potential utility in identifying E. coli infections compared to other pathogens.

Dietary supplementation of proteases on growth performance, nutrient digestibility, blood characteristics and gut microbiota of growing pigs fed sorghum-based diets

Low-tannin sorghum is an excellent energy source in pig diets. However, sorghum contains several anti-nutritional factors that may have negative effects on nutrient digestibility. The impacts of proteases on growth performance, nutrient digestibility, blood parameters, and gut microbiota of growing pigs fed sorghum-based diets were studied in this study. Ninety-six pigs (20.66 ± 0.65 kg BW) were allocated into three groups (eight pens/group, four pigs/pen): (1) CON (control diet, sorghum-based diet included 66.98% sorghum), (2) PRO1 (CON + 200 mg/kg proteases), (3) PRO2 (CON + 400 mg/kg proteases) for 28 d. No differences were observed in growth performance and apparent total tract digestibility (ATTD) of nutrients between CON and PRO1 groups. Pigs fed PRO2 diet had increased (P < 0.05) BW on d 21 and 28, and increased (P < 0.05) average daily gain during d 14-21 and the overall period compared with pigs fed CON diet. In addition, pigs fed PRO2 diet had improved (P < 0.05) ATTD of gross energy, CP, and DM compared with pigs fed CON and PRO1 diets. Pigs fed PRO2 diet had lower (P < 0.05) plasma globulin (GLB) level and higher (P < 0.05) plasma glucose, albumin (ALB) and immunoglobulin G levels, and ALB/GLB ratio than pigs fed CON and PRO1 diets. Furthermore, pigs fed PRO2 diet had decreased (P < 0.05) the relative abundance of Acidobacteriota at the phylum level and increased (P < 0.05) the relative abundance of Prevotella_9 at the genus level. The linear discriminant analysis effect size analysis also showed that pigs fed PRO2 diet had significantly enriched short-chain fatty acid-producing bacteria, such as Subdoligranulum and Parabacteroides. In conclusion, protease supplementation at 400 mg/kg improved the growth performance of growing pigs fed sorghum-based diets, which may be attributed to the improvement of nutrient digestibility, host metabolism, immune status and associated with the altered gut microbiota profiles.

Target-Driven Annular DNA Walker Coupled with Electrochemiluminescent Silicon Quantum Dots for APE1 Bioanalysis

Functional DNA walkers with substantial nanostructures have been extensively investigated; however, their stability still faces challenges when exposed to diverse nuclease in clinical biological samples, resulting in the unreliability of actual assessment. This work proposed a target-driven annular DNA walker with enhanced stability enabling the sensitive and reliable response to different concentrations of apurinic/apyrimidinic endonuclease 1 (APE1), by preparing silicon quantum dots (SiQDs) as electrochemiluminescence (ECL) emitters. Specifically, the SiQDs showed significant strong and stable ECL signals by purifying the microenvironment of SiQDs through the dialysis removal of the gel-like layers surrounding the SiQDs. The relative standard deviation (RSD) of their ECL signal had been improved 16.59 times under consecutive scanning compared to that of SiQDs without dialysis, demonstrating a significant improvement in ECL stability. Subsequently, in the presence of APE1, the designed annular DNA walker was activated to move along the numerous quenching probes within the continuous cross-based DNA orbits, which were immobilized to the SiQD-modified electrode, providing ECL readout signals. The linear range of this ECL biosensor was 1.0 × 10-13 U·μL-1 to 1.0 × 10-7 U·μL-1, and the limit of detection (LOD) was as low as 1.766 × 10-14 U·μL-1. This work provides a novel structure of a DNA walker with nuclease resistance for clinical sample detection and designs a new strategy for synthesizing SiQDs with favorable ECL performance, tremendously expanding the ECL application of SiQDs.

Effects of dietary methionine supplementation from different sources on growth performance and meat quality of barrows and gilts

Methionine is indispensable for growth and meat formation in pigs. However, it is still unclear that increasing dietary sulphur-containing amino acid (SAA) levels using different methionine sources affects the growth performance and meat quality of barrows and gilts. To investigate this, 144 pigs (half barrows and half gilts) were fed the control (100% SAA, CON), DL-Methionine (125% SAA, DL-Met)-supplemented, or OH-Methionine (125% SAA, OH-Met)-supplemented diets during the 11-110 kg period. The results showed that plasma methionine levels varied among treatments during the experimental phase, with increased plasma methionine levels observed following increased SAA consumption during the 25-45 kg period. In contrast, pigs fed the DL-Met diet had lower plasma methionine levels than those fed the CON diet (95-110 kg). Additionally, gilts fed the DL-Met or OH-Met diets showed decreased drip loss in longissimus lumborum muscle (LM) compared to CON-fed gilts. OH-Met-fed gilts had higher pH45min values than those fed the CON or DL-Met diets, whereas OH-Met-fed barrows had higher L45min values than those fed the CON or DL-Met diets. Moreover, increased consumption of SAA, regardless of the methionine source, tended to decrease the shear force of the LM in pigs. In conclusion, this study indicates that increasing dietary levels of SAA (+25%) appeared to improve the meat quality of gilts by decreasing drip loss and increasing meat tenderness.

Spherical nucleic acid enzyme programmed network to accelerate CRISPR assays for electrochemiluminescence biosensing applications

Given the targeted binding ability and cleavage activity of the emerging CRISPR/Cas12a assay which transduces the target into its cleavage activity exhibited broadly prospective applications in integrated sensing and actuating system. Here, we elaborated a universal approach to quickly activate CRISPR/Cas12a for low-abundance biomarker detection based on the amplification strategy of a target-induced spherical nucleic acid enzyme (SNAzyme) network that could accelerate the output of activators. Specifically, multifunctional Y-shaped probes and hairpin probes (HPs, which contained the specific sequence of the activators of CRISPR/Cas12a and the substrate chain of DNAzyme) were rationally designed to construct SNAzyme. Target recognition induced disassembly of the Y-shaped probes, which released DNAzyme strands to active DNAzyme and accompanied by SNAzyme self-assembly into SNAzyme network. Interestingly, compared with randomly dispersed SNAzyme, the reaction kinetics of the SNAzyme network enhanced 1.6 times in response to Α-methyl acyl-CoA racemase (AMACR, a biomarker for prostate cancer), which was attributed to the promoted catalytic efficiency of DNAzyme by the confined SNAzyme network. Benefiting from these, the prepared biosensor based on electrochemiluminescence (ECL) platform by loading AuAg nanoclusters (AuAgNCs) into metal-organic framework-5 (MOF-5) exhibited satisfying detection performance for AMACR with a wide linear range (0.001 μg/mL to 100 μg/mL) and a low detection limit (1.0 × 10-4 μg/mL, which exhibited significant potential in clinical diagnoses.

Simultaneous subset tracing and miRNA profiling of tumor-derived exosomes via dual-surface-protein orthogonal barcoding

The clinical potential of miRNA-based liquid biopsy has been largely limited by the heterogeneous sources in plasma and tedious assay processes. Here, we develop a precise and robust one-pot assay called dual-surface-protein-guided orthogonal recognition of tumor-derived exosomes and in situ profiling of microRNAs (SORTER) to detect tumor-derived exosomal miRNAs and enhance the diagnostic accuracy of prostate cancer (PCa). The SORTER uses two allosteric aptamers against exosomal marker CD63 and tumor marker EpCAM to create an orthogonal labeling barcode and achieve selective sorting of tumor-specific exosome subtypes. Furthermore, the labeled barcode on tumor-derived exosomes initiated targeted membrane fusion with liposome probes to import miRNA detection reagents, enabling in situ sensitive profiling of tumor-derived exosomal miRNAs. With a signature of six miRNAs, SORTER differentiated PCa and benign prostatic hyperplasia with an accuracy of 100%. Notably, the diagnostic accuracy reached 90.6% in the classification of metastatic and nonmetastatic PCa. We envision that the SORTER will promote the clinical adaptability of miRNA-based liquid biopsy.

Mapping the Initial Stages of a Protective Pathway that Enhances Catalytic Turnover by a Lytic Polysaccharide Monooxygenase

Oxygenase and peroxygenase enzymes generate intermediates at their active sites which bring about the controlled functionalization of inert C-H bonds in substrates, such as in the enzymatic conversion of methane to methanol. To be viable catalysts, however, these enzymes must also prevent oxidative damage to essential active site residues, which can occur during both coupled and uncoupled turnover. Herein, we use a combination of stopped-flow spectroscopy, targeted mutagenesis, TD-DFT calculations, high-energy resolution fluorescence detection X-ray absorption spectroscopy, and electron paramagnetic resonance spectroscopy to study two transient intermediates that together form a protective pathway built into the active sites of copper-dependent lytic polysaccharide monooxygenases (LPMOs). First, a transient high-valent species is generated at the copper histidine brace active site following treatment of the LPMO with either hydrogen peroxide or peroxyacids in the absence of substrate. This intermediate, which we propose to be a CuII-(histidyl radical), then reacts with a nearby tyrosine residue in an intersystem-crossing reaction to give a ferromagnetically coupled (S = 1) CuII-tyrosyl radical pair, thereby restoring the histidine brace active site to its resting state and allowing it to re-enter the catalytic cycle through reduction. This process gives the enzyme the capacity to minimize damage to the active site histidine residues "on the fly" to increase the total turnover number prior to enzyme deactivation, highlighting how oxidative enzymes are evolved to protect themselves from deleterious side reactions during uncoupled turnover.

Engineering Molecular Emission Centers of Carbon Dots to Boost the Electrochemiluminescence for the Detection of Cancer Cells

Despite the fact that electrochemiluminescent (ECL) performance of carbon dots (CDs) could be improved by modulating their surface defects, they are still restricted by inferior controllability and poor reproducibility. In this work, we disclosed a new approach for synthesizing luminescent groups rich in CDs (Lu-CDs) by engineering the luminol as molecular emission centers into the CDs, which exhibited an 80-fold stronger ECL intensity at an ECL onset potential of 0.6 V than the CDs without pre-implanted luminol. Different from the significant deviation between the ECL and fluorescence emission of other surface state-dominated CDs, the ECL emission of Lu-CDs was nearly consistent with its fluorescence emission at 465 nm, which was defined as the molecular emission dominated-ECL CDs herein. To prove this principle, the Lu-CDs were employed to construct an ECL biosensor for MCF-7 cell analysis based on the cell direct recognition and amplification strategy, which made the MCF-7 cells as nanomachines via specific binding with aptamer signal probes on the DNA triangular scaffold. The proposed biosensor displayed a wide detection range from 101 to 104 cell mL-1 and a low detection limit of 8.91 cells mL-1. Overall, this work not only presents a new strategy for preparing CDs with high controllability and excellent reproducibility but also provides a platform for tumor cell sensing.

Multicomponent Synthesis of the SARS-CoV-2 Main Protease Inhibitor Nirmatrelvir

In the wake of the Covid-19 pandemic, it has become clear that global access to efficacious antiviral drugs will be critical to combat future outbreaks of SARS-CoV-2 or related viruses. The orally available SARS-CoV-2 main protease inhibitor nirmatrelvir has proven an effective treatment option for Covid-19, especially in compromised patients. We report a new synthesis of nirmatrelvir featuring a highly enantioselective biocatalytic desymmetrization (>99% ee) and a highly diastereoselective multicomponent reaction (>25:1 dr) as the key steps. Our route avoids the use of transition metals and peptide coupling reagents, resulting in an overall highly efficient and atom-economic process.

Impact of COVID-19 on the distribution of pathogenic bacteria in the lower respiratory tract of the elderly

BACKGROUND

To investigate the distribution of bacterial pathogens of lower respiratory tract infection (LRTI) in hospitalized elderly patients during the COVID-19 epidemic and to explore the influence of COVID-19 on the distribution of bacterial pathogens, to provide guidance for clinical diagnosis.

METHODS

Specimens of sputum from elderly LRTIs patients at Fuding Hospital of China were consecutively collected from October 2022 to January 2023. Cultures and identification were done, and RT-PCR was employed to detect SARS-Cov-2 nucleic acid.

RESULTS

A total of 195 isolates were characterized in 163 sputum samples of consecutive hospitalized elderly patients, of which 11.3% were Gram-positive bacteria and 88.7% were Gram-negative. The top of frequently isolated pathogens was Klebsiella pneumonia (30.3%), Pseudomonas aeruginosa (19.0%), Acinetobacter baumannii (12.8%), Stenotrophomonas maltophili, (7.7%), Escherichia coli (7.2%). According to the results of novel coronavirus nucleic acid detection, the 163 patients were divided into COVID-19 group and non-COVID control (CNT) group. The comparison of bacterial distribution between the groups revealed that Stenotrophomonas maltophilia was lower in the COVID-19 than in the CNT group, while A. baumannii was higher in the COVID-19 group, and the difference was statistically significant (p < .05).

CONCLUSION

The major bacteria identified in sputum culture of hospitalized elderly patients were K. pneumonia, P. aeruginosa, A. baumannii, S. maltophilia, and E. coli. Furthermore, the distribution of S. maltophilia and A. baumannii between the COVID-19 and CNT groups was found to be significantly different (p < .05), while there were no significant differences in the distribution of other bacteria.

Identification and Quantification of 5-Methylcytosine and 5-Hydroxymethylcytosine on Random DNA Sequences by a Nanoconfined Electrochemiluminescence Platform

5-Methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are two of the most abundant epigenetic marks in mammalian genomes, and it has been proven that these dual epigenetic marks give a more accurate prediction of recurrence and survival in cancer than the individual mark. However, due to the similar structure and low expression of 5mC and 5hmC, it is challenging to distinguish and quantify the two methylation modifications. Herein, we employed the ten-eleven translocation family dioxygenases (TET) to convert 5mC to 5hmC via a specific labeling process, which realized the identification of the two marks based on a nanoconfined electrochemiluminescence (ECL) platform combined with the amplification strategy of a recombinase polymerase amplification (RPA)-assisted CRISPR/Cas13a system. Benefiting from the TET-mediated conversion strategy, a highly consistent labeling pathway was developed for identifying dual epigenetic marks on random sequence, which reduced the system error effectively. The ECL platform was established via preparing a carbonized polymer dot embedded SiO₂ nanonetwork (CPDs@SiO₂), which exhibited higher ECL efficiencies and more stable ECL performance compared to those of the scattered emitters due to the nanoconfinement-enhanced ECL effect. The proposed bioanalysis strategy could be employed for the identification and quantification of 5mC and 5hmC in the range from 100 aM to 100 pM, respectively, which provides a promising tool for early diagnosis of diseases associated with abnormal methylation.

Insights of Life Molecules' Dynamic Distribution in Live Cells via Sequence-Structure Bispecific Fluorescent RNA

Life molecules' distributions in live systems construct the complex dynamic reaction networks, whereas it is still challenging to demonstrate the dynamic distributions of biomolecules in live systems. Herein, we proposed a dynamic analysis strategy via sequence-structure bispecific RNA with state-adjustable molecules to monitor the dynamic concentration and spatiotemporal localization of these biomolecules in live cells based on the new insight of fluorescent RNA (FLRNA) interactions and their mechanism of fluorescence enhancement. Typically, computer-based nucleic acid-molecular docking simulation and molecular theoretical calculation have been proposed to provide a simple and straightforward method for guiding the custom-design of FLRNA. Impressively, a novel FLRNA with sequence and structure bispecific RNA named as a structure-switching aptamer (SSA) was introduced to monitor the real-time concentration and spatiotemporal localization of biomolecules, contributing to a deeper insight of the dynamic monitoring and visualization of biomolecules in live systems.

AgInZnS quantum dots as anodic emitters with strong and stable electrochemiluminescence for biosensing application

Quantum dots (QDs) have become promising electrochemiluminescence (ECL) emitters with high quantum yield and size-tunable luminescence. However, most QDs generate strong ECL emission at the cathode, developing anodic ECL-emitting QDs with excellent performance is challenging. In this work, low-toxic quaternary AgInZnS QDs synthesized by a one-step aqueous phase method were used as novel anodic ECL emitters. AgInZnS QDs exhibited strong and stable ECL emission and a low excitation potential, which could avoid the side reaction of oxygen evolution. Furthermore, AgInZnS QDs displayed high ECL efficiency (Φ_ECL) of 5.84, taking the Φ_ECL of Ru(bpy)₃²⁺/tripropylamine (TPrA) ECL system as 1. Compared to AgInS₂ QDs without Zn doping and traditional anode luminescent CdTe QDs, the ECL intensity of AgInZnS QDs was 1.62 times and 3.64 times higher than that of AgInS₂ QDs and CdTe QDs, respectively. As a proof-of-concept, we further designed an "on-off-on" ECL biosensor for detecting microRNA-141 based on a dual isothermal enzyme-free strand displacement reaction (SDR), which not only to achieve the cyclic amplification of the target and ECL signal, but also to construct a switch of the biosensor. The ECL biosensor had a wide linear range from 100 aM to 10 nM with a low detection limit of 33.3 aM. Together, the constructed ECL sensing platform is a promising tool for rapid and accurate diagnosis of clinical diseases.

DNA-Guided One-Dimensional Plasmonic Nanostructures for the SERS Bioassay

Plasmonic nanostructures have a desirable surface-enhanced Raman scattering (SERS) response related to particle spacing. However, precisely controlling the distance of plasmonic nanostructures is still a challenge. DNA has the merit of specific recognition, and flexible modification of functional groups, which can be used to flexibly adjust the gaps between plasmonic nanostructures for improving the stability of SERS. In this paper, DNA-guided gold nanoparticles formed one-dimensional ordered structures and they were self-assembled at the water-oil interface by a bottom-up approach. Notably, an output switching strategy successfully transfers a small amount of target into a large amount of reporter DNA; thereby, Raman probes are captured on the sensing interface and achieve the SERS assay of microRNA 155 (miRNA-155). This study is an exciting strategy for obtaining ordered plasmonic structures and providing surveillance, which is important for the clinical diagnosis of early-stage cancer.

Target-mediated self-assembly of DNA networks for sensitive detection and intracellular imaging of APE1 in living cells

Herein, giant DNA networks were assembled from two kinds of functionalized tetrahedral DNA nanostructures (f-TDNs) for sensitive detection and intracellular imaging of apurinic/apyrimidinic endonuclease 1 (APE1) as well as gene therapy in tumor cells. Impressively, the reaction rate of the catalytic hairpin assembly (CHA) reaction on f-TDNs was much faster than that of the conventional free CHA reaction owing to the high local concentration of hairpins, spatial confinement effect and production of giant DNA networks, which significantly enhanced the fluorescence signal to achieve sensitive detection of APE1 with a limit of 3.34 × 10^-8 U μL^-1. More importantly, the aptamer Sgc8 assembled on f-TDNs could enhance the targeting activity of the DNA structure to tumor cells, allowing it to endocytose into cells without any transfection reagents, which could achieve selective imaging of intracellular APE1 in living cells. Meanwhile, the siRNA carried by f-TDN1 could be accurately released to promote tumor cell apoptosis in the presence of endogenous target APE1, realizing effective and precise tumor therapy. Benefiting from the high specificity and sensitivity, the developed DNA nanostructures provide an excellent nanoplatform for precise cancer diagnosis and therapy.

Rapid simultaneous SERS detection of dual myocardial biomarkers on single-track finger-pump microfluidic chip

Acute myocardial infarction (AMI) is a serious disease with high mortality that afflicts many people around the world. The main cause of death from AMI was the inaccurate early diagnosis, which resulted from the medical treatment might be a delay. Therefore, it is crucial to achieve the rapid detection of AMI. The cardiac troponin I (cTnI) level in human serum may significantly increase as the myocardial membrane ruptured, and the creatine kinase-MB (CK-MB) was also associated with the AMI recurrence and the infarct size of myocardial infarction. Both of them are regarded as important cardiac biomarkers for the early diagnosis of AMI. Therefore, we chose these two cardiac biomarkers as indicators for simultaneous detection. We proposed a single-track finger-pump microfluidic chip for simultaneous surface-enhanced Raman scattering (SERS) detection of cTnI and CK-MB. The entire detection process takes only 5 min without the cumbersome syringe pump. Meanwhile, it enables multiple reagent additions and removals of the unbonded reactants. This microfluidic sensor employed "sandwich" immunoassays based on SERS nanoprobes, AMI biomarkers, and magnetic beads. It is possible to detect two cardiac biomarkers simultaneously in a single measurement, greatly simplifying the detection process and reducing the detection time. Magnetic beads with SERS nanoprobes were separated and captured in the microchamber by a round magnet integrated into the chip. Our results showed that the detection limits of cTnI and CK-MB could reach to 0.01 ng mL^-1, respectively. The limit of detections (LODs) match with the clinical threshold values for AMI biomarkers. It is believed that the proposed single-track finger-pump microfluidic chip can be used as an effective tool for determining early AMI.

Programmable Y-Shaped Probes with Proximity Bivalent Recognition for Rapid Electrochemiluminescence Response of Acute Myocardial Infarction

Herein, an exogenous luminophore-free and disposable electrochemiluminescence (ECL) biosensor was established for rapid response of acute myocardial infarction (AMI) using programmable Y-shaped probes (Y-probes) with proximity bivalent recognition. Specifically, the indium tin oxide thin film coated glass electrode (ITO) was modified with urchin-like porous TiO₂ microspheres (pTiO₂ MSs), which could achieve strong and stable ECL in S₂O₈^2- solution due to the dual promoting effect of the coreaction accelerator pTiO₂ MSs, exhibiting 2.7-fold higher ECL intensity in comparison with that of bare ITO. Moreover, the Y-probes as bivalent recognition elements containing two kinds of cardiac troponin I (cTnI, a biomarker of AMI) aptamers and a linker labeled with ferrocene (L-Fc) were designed to export a "signal off" mode. When the target cTnI was in the proximity of the Y-probes, the L-Fc was separated from the electrode surface due to the proximity recognition of cTnI and its aptamers, achieving the highly effective recovery of ECL, which allowed for a much more rapid detection of cTnI than the sandwich-type immunoassay. As a proof of concept, an exogenous luminophore-free and disposable ECL platform for rapid and sensitive monitoring of cTnI was obtained and displayed a desired linear range from 100 fg mL^-1 to 100 ng mL^-1 with a limit of detection (LOD) of 30.1 fg mL^-1, which can be ingeniously expanded as a portable home tester with ECL biosensors developments.

Electrochemiluminescence covalent organic framework coupling with CRISPR/Cas12a-mediated biosensor for pesticide residue detection

The trace detection of pesticide residue becomes particularly important since increasing attentions have been attached to food safety. Herein, we developed an electrochemiluminescence (ECL) covalent organic framework (COF) based-biosensor for trace pesticide detection coupling with CRISPR/Cas12a-mediated signal accumulation strategy. Firstly, the target conversion was carried out with an aptamer-assembled magnetic spherical nucleic acids, which can convert acetamiprid to activator DNA, triggering the CRISPR/Cas12a to make quenching probes far away from electrode for signal accumulation. The COF with stable and strong ECL was synthesized by a condensation reaction between the perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and melamine (MA), due to the highly ordered arrangement of the PTCDA luminescence units among COF structure and the pore confinement effect. Moreover, the designed assay method was successfully employed to detect the residual level of acetamiprid in real sample and expected to be widely used in pesticide-related food safety.

Ordered heterogeneity in dual-ligand MOF to enable high electrochemiluminescence efficiency for bioassay with DNA triangular prism as signal switch

Herein, the microRNA-141 electrochemiluminescence (ECL) bioassay was developed using the dual-ligand metal-organic framework (d-MOF) with ordered heterogeneity, which simultaneously contained the luminophore ligands (1,1,2,2-tetra(4-carboxylbiphenyl)ethylene, denoted as TCBPE) and the coreactant ligands (1,4-diazabicyclo[2.2.2]octane, denoted as DN₂H₂). The resultant d-MOF revealed significantly enhanced ECL intensity without any exogenous coreactants, which was 3.53 times higher in comparison with that of single-ligand MOF (only TCBPE as ligands) even with the addition of exogenous DN₂H₂. Thanks to the ordered heterogeneity in d-MOF, the intramolecular rotation of TCBPE was restricted via oriented coordination and the spatial location of DN₂H₂ was reasonably arranged due to the framework structure, which could not only enhance the excitation efficiency but also improve the electron-transfer efficiency based on the synergistic enhancement effect between structures and compositions in micro/nano confined space. Based on this, the proposed biosensor employed a novel DNA triangular prism (DNA TP) as signal switch to detect microRNA-141, achieving the low detection limit at the level of 22.9 aM and a broad linear ranging from 100 aM to 100 pM. The precise design of the ordered d-MOFs by co-assembling the luminophore and coreactant ligands holds a promise strategy to achieve ECL MOFs and construct the ECL biosensors in diagnostic analysis.

Wireframe Orbit-Accelerated Bipedal DNA Walker for Electrochemiluminescence Detection of Methyltransferase Activity

In spite of the DNA walkers executing the signal accumulation task in the process of moving along the predetermined paths, the enhancement of walking dynamics and walking path controllability are still challenging due to the unprogrammed arrangements of DNA orbits. Taking these dilemmas into account, a bipedal DNA walker was designed skillfully by the virtue of wireframe orbits assembled by DNA cubes in order, which improved the efficiency and the continuity of walking. It could be attributed to the fact that both the contact chance and the dynamic interaction between walking strands and designated orbits were beneficial to minimize the possibility of derailment and improve the accumulation of signal. In addition, the hollow titanium dioxide nanospheres coated with rubrene (Rub@TiO₂ NSs) were prepared by the etching of inner silicon dioxide nanoparticles (SiO₂ NPs) to regulate the distribution pattern of rubrene (Rub) molecules and expose more electrochemically active sites for high-efficient electrochemiluminescence (ECL). Benefiting by the pore confinement-enhanced ECL, the electron and mass transfer was significantly accelerated because of the hollow structure of Rub@TiO₂ NSs. Subsequently, endogenous dissolved oxygen as the coreactant and palladium nanoparticles (Pd NPs) as the coreaction accelerator were employed to constitute a ternary ECL system with explosive signal response. Combining with this ECL platform, the bipedal walker activated by the target can autonomously and directionally move on the DNA wireframe orbits to release the quenching probes continuously. In this way, the biosensor displayed a low detection limit (2.30 × 10^-8 U·mL^-1) and a wide linear range (1.0 × 10^-7 to 1.0 × 10^-1 U·mL^-1) for the sensitive detection of Dam methyltransferase (Dam MTase) activity. Therefore, a novel strategy for the accurate quantification of epigenetic targets was developed by virtue of improving the walking dynamics of DNA walker and amplifying the ECL of Rub molecules.

Versatile Electrochemical Biosensor Based on the Target-Controlled Capture and Release of DNA Nanotubes for the Ultrasensitive Detection of Multiplexed Biomarkers

Herein, an ultrasensitive and versatile electrochemical biosensor was developed through the target-controlled capture and release of signal probe-loaded DNA nanotube for the ultrasensitive detection of two different types of cancer-related biomarkers, microRNA-21 (miRNA-21) and glutathione (GSH). In this system, target 1 (miRNA-21) first triggered duplex-specific nuclease (DSN)-assisted recycle amplification to generate numerous disulfide-linked DNA strands (DL), which could effectively capture DNA nanotube to immobilize methylene blue (MB) to produce remarkable electrochemical signals and achieve the ultrasensitive detection of miRNA-21 with a detection limit down to 32.6 aM. Furthermore, in the presence of target 2 (GSH), the electrochemical signal was significantly reduced by a thiol-disulfide bond exchange reaction on DL to release MB-immobilized DNA nanotubes away from the sensing interface, which enabled the sensitive analysis of GSH with a detection limit of 0.379 nM. Impressively, this strategy could achieve ultrasensitive detection of different types of biomarkers to prominently lessen false-positive responses from the current sensing methods toward a single biomarker or the same type of biomarker and remarkably heighten the accuracy and precision of early cancer diagnosis. Meanwhile, the proposed electrochemical biosensor made it possible to realize the regenerative analysis of targets over four times without extra fuel, which could conspicuously improve the analytical efficiency compared with that of traditional biosensing assays. As a result, this study might open up novel insights to design a versatile and multifunctional sensing platform and encourage deeper exploration for detecting different types of biomarkers in the fields of early disease diagnosis and biochemical research.

Discrimination between Cancer Cells and DNA-Damaged Cells: Pre-miRNA Region Recognition Based on Hyperbranched Hybrid Chain Reaction Amplification for Simultaneous Sensitive Detection and Imaging of miRNA and Pre-miRNA

Herein, a novel region recognition of precursor microRNA (Pre-miRNA) based on hyperbranched hybrid chain reaction (HB-HCR) amplification was constructed to effectively eliminate the interference of Pre-miRNA to the mature microRNA (miRNA) by establishing the linear mapping relation between the two fluorescence signals produced by the miRNA sequence in the Pre-miRNA and Pre-miRNA residues to first realize simultaneous sensitive detection of Pre-miRNA and miRNA as well as highly sensitive imaging of intracellular Pre-miRNA and miRNA, which solves one main challenge of in vitro tumor disease diagnostics: inaccurate detection of tumor-induced miRNA changes. Impressively, this strategy easily distinguishes cancer cells from normal cells and DNA-damaged cells by the difference in miRNA and Pre-miRNA expression, which provides an innovative approach for accurate clinical diagnosis of cancer and precise treatment of prognosis.

Ag@Pyc Nanocapsules as Electrochemiluminescence Emitters for an Ultrasensitive Assay of the APE1 Activity

Herein, Ag@pyrenecarboxaldehyde nanocapsules (Ag@Pyc nanocapsules) as emitters were prepared to construct an ultrasensitive electrochemiluminescence (ECL) biosensor for the detection of the human apurinic/apyrimidinic endonuclease1 (APE1) activity. Ag nanoparticles on the surface of Pyc nanocapsules as coreaction accelerators could significantly promote coreactant peroxydisulfate (S₂O₈^2-) to generate massive reactive intermediates of sulfate radical anion (SO₄^•-), which interacted with the Pyc nanocapsules to achieve a strong ECL response. In addition, with the aid of APE1-triggered 3D DNA machine, trace target could be converted into a large number of mimic targets (MTs), which were positively correlated with the activity of APE1. Consequently, the proposed ECL biosensor realized an ultrasensitive detection of APE1 activity with an exceptional linear working range from 5 × 10^-10 to 5 × 10^-4 U·μL^-1 and a lower limit of detection of 1.36 × 10^-11 U·μL^-1. This strategy provided a new approach to construct an efficient ternary system for the detection of biomolecules and early diagnosis of diseases.

One-Step Digital Droplet Auto-Catalytic Nucleic Acid Amplification with High-Throughput Fluorescence Imaging and Droplet Tracking Computation

Digital droplet technology has emerged as a powerful new tool for biomarker analysis. Temperature cycling, enzymes, and off-chip processes are, nevertheless, always required. Herein, we constructed a digital droplet auto-catalytic hairpin assembly (ddaCHA) microfluidic system to achieve digital quantification of single-molecule microRNA (miRNA). The designed continuous chip integrates droplet generation, incubation, and fluorescence imaging on the chip, avoiding the requirement for extra droplet re-collection and heating operations. Clearly, the digital readout was obtained by partitioning miRNA into many individual pL-sized small droplets in which the target molecule is either present ("positive") or absent ("negative"). Importantly, the suggested enzyme-free auto-catalytic hairpin assembly (aCHA) in droplets successfully mitigated the effects of the external environment and thermal cycling on droplets, and its reaction rate is significantly superior to that of traditional CHA. We got excellent sensitivity with a linear correlation from 1 pM to 10 nM and a detection limit of 0.34 pM in the fluorescence spectrum section, as well as high selectivity to other miRNAs. Furthermore, the minimum target concentration could be reduced to 10 fM based on the high-throughput tracking computation of fluorescent droplets with a self-developed Python script, and the fluorescence intensity distribution agreed well with the theoretical value, demonstrating that it is feasible to detect miRNA efficiently and accurately, which has great potential applications in clinical diagnostics and biochemical research.

Construction of Fast-Walking Tetrahedral DNA Walker with Four Arms for Sensitive Detection and Intracellular Imaging of Apurinic/Apyrimidinic Endonuclease 1

Herein, a novel tetrahedral DNA walker with four arms was engineered to travel efficiently on the 3D-tracks via catalyzed hairpin assembly autonomously, realizing the sensitive detection and activity assessment as well as intracellular imaging of apurinic/apyrimidinic endonuclease 1 (APE1). In contrast to traditional DNA walkers, the tetrahedral DNA walker with the rigid 3D framework structure and nonplanar multi-sites walking arms endowed with high collision efficiency, showing a fast walking rate and high nuclease resistance. Impressively, the initial rate of the tetrahedral DNA walker with four arms was 4.54 times faster than that of the free bipedal DNA walker and produced a significant fluorescence recovery in about 40 min, achieving a sensitive detection of APE1 with a low detection limit of 5.54× 10^-6 U/μL as well as ultrasensitive intracellular APE1 fluorescence activation imaging. This strategy provides a novel DNA walker for accurate identification of low-abundance cancer biomarker and potential medical diagnosis.

Pyrenecarboxaldehyde encapsulated porous TiO2 nanoreactors for monitoring cellular GSH levels

Recently, ternary electrochemiluminescence (ECL) system has become a hot research topic due to its great potential for improving ECL efficiency by promoting the generation of intermediates. However, it is still a great challenge to increase the utilization rate of intermediates in a ternary ECL system. Herein, we propose a strategy to increase the utilization rate of intermediates by designing pyrenecarboxaldehyde (Pyc) encapsulated porous titania (pTiO₂) nanospheres (Pyc@pTiO₂) as ECL nanoreactors for an integrated ternary (luminophore/coreactant/co-reaction accelerator, Pyc/S₂O₈^2-/TiO₂) ECL system construction. Specifically, pTiO₂ acted as an ECL co-reaction accelerator, in which Pyc could obtain electrons from the conduction band of TiO₂ to produce more SO₄˙^-, increasing its emissions. Simultaneously, pTiO₂ could provide confined reaction spaces to effectively shorten the diffusion distance, extend the lifetime of free radicals, increase the utilization rate of intermediates and improve the efficiency of the ternary ECL system. As a proof of concept, the Pyc@pTiO₂ nanoreactors-based sensing platform was successfully constructed to sensitively monitor cellular GSH levels. Overall, this work for the first time proposed an avenue to increase the utilization rate of intermediates in a ternary ECL system, which opened a new route for ECL biosensing in cell analysis applications.

A Novel Ratiometric Electrochemical Biosensor Using Only One Signal Tag for Highly Reliable and Ultrasensitive Detection of miRNA-21

Herein, a novel ratiometric electrochemical biosensor with methylene blue (MB) as the only one signal tag was proposed for highly reliable and ultrasensitive detection of microRNA-21 (miRNA-21) under the assistance of an intelligent target-induced dual signal amplification (T-DSA). First, a small amount of target miRNA-21 could produce abundant mimic targets DNA S1 and Zn²⁺ through target-induced recycle and acid dissolution, respectively. Then, S1 triggered rolling circle amplification (RCA) to generate functional DNA nanospheres (DSP) encoded by DNAzyme and substrate sequence for loading numerous signal tag MB with a remarkable electrochemical signal (signal on), and the Zn²⁺ cofactor mediated the nonviolent DNAzyme-catalyzed cleavage of DSP to sharply release MB with obviously reduced electrochemical responses (signal off). Impressively, our strategy could controllably load and release the only signal tag MB through the well-designed DSP to effectively avoid the false positive responses caused by the non-ideal upright state of DNA probes connected to electrodes in traditional distance-dependent signal adjustment ratiometric strategies with two different signal tags. Meanwhile, with the aid of innovative T-DSA recycle and RCA-produced functional DSP, the detection sensitivity of this sensing platform was significantly improved. As a result, the proposed biosensor successfully realized highly reliable and ultrasensitive detection of miRNA-21 with a detection limit down to 26.7 aM, which shows exceptional promise in biological analysis and medical diagnosis.

An Engineered Cytidine Deaminase for Biocatalytic Production of a Key Intermediate of the Covid-19 Antiviral Molnupiravir

The Covid-19 pandemic highlights the urgent need for cost-effective processes to rapidly manufacture antiviral drugs at scale. Here we report a concise biocatalytic process for Molnupiravir, a nucleoside analogue recently approved as an orally available treatment for SARS-CoV-2. Key to the success of this process was the development of an efficient biocatalyst for the production of N-hydroxy-cytidine through evolutionary adaption of the hydrolytic enzyme cytidine deaminase. This engineered biocatalyst performs >85 000 turnovers in less than 3 h, operates at 180 g/L substrate loading, and benefits from in situ crystallization of the N-hydroxy-cytidine product (85% yield), which can be converted to Molnupiravir by a selective 5'-acylation using Novozym 435.

Epigenetic Quantification of 5-Hydroxymethylcytosine Signatures via Regulatable DNAzyme Motor Triggered by Strand Displacement Amplification

DNA methylation predominantly occurs within the CpG dinucleotide, which is the main epigenetic form of gene expression regulation in mammals. Genomic DNA with CpG sites has different sequence lengths and complex secondary structures, resulting in the complexity and diversity of the samples. Therefore, highly efficient quantification of DNA methylation in complex samples remains challenging. Herein, the regulatable DNAzyme motor triggered by strand displacement amplification (SDA) was designed to quantify 5-hydroxymethylcytosine (5hmC) signatures as a model. Briefly, the 5hmC sites as primary target were specifically labeled with DNA primers and converted into a large number of single-stranded DNA (secondary target) via the SDA reaction which could activate the DNAzyme motor. With the increase of secondary target, the DNAzyme motor gradually recovered its activity and could continuously cleave the track strands labeled quenching probes, causing electrochemiluminescence signal recovery and detection limit down to 0.49 fM for 5hmC. This strategy provides a new route to quantify natural base modifications in DNA and would hold promising potential for the early diagnosis of cancer and other diseases related to 5hmC.

Sodium MRI at 7T for Early Response Evaluation of Intracranial Tumors following Stereotactic Radiotherapy Using the CyberKnife

BACKGROUND AND PURPOSE

Conventionally, early treatment response to stereotactic radiotherapy in intracranial tumors is often determined by structural MR imaging. Tissue sodium concentration is altered by cellular integrity and energy status in cells. In this study, we aimed to investigate the feasibility of sodium MR imaging at 7T for the preliminary evaluation of radiotherapeutic efficacy for intracranial tumors.

MATERIALS AND METHODS

Data were collected from 16 patients (12 men and 4 women, 24-75 years of age) with 22 intracranial tumors who were treated with stereotactic radiation therapy using CyberKnife at our institution between December 1, 2016, and August 15, 2019. Sodium MR imaging was performed at 7T before and 48 hours, 1 week, and 1 month after CyberKnife radiation therapy. Tissue sodium concentration (TSC) was calculated and analyzed based on manually labeled regions of tumors.

RESULTS

Ultra-high-field sodium MR imaging clearly showed the intratumoral signal, which is significantly higher than that of normal tissue (t = 5.250, P <.001)., but the edema zone has some influence. The average TSC ratios of tumor to CSF in the 22 tumors, contralateral normal tissues, edema zones, frontal cortex, and frontal white matter were 0.66 (range, 0.23-1.5), 0.30 (range, 0.15-0.43), 0.58 (range, 0.25-1.21), 0.25 (range, 0.17-0.42), and 0.30 (range, 0.19-0.49), respectively. A total of 12 tumors in 8 patients were scanned at 48 hours, 1 week, and 1 month after treatment. The average TSC at 48 hours after treatment was 0.06 higher than that before treatment and began to decrease at 1 week. The TSC ratios of 10 continued to decline and 2 tumors increased at 1 month, respectively. Tumor volume decreased by 2.4%-99% after 3 months.

CONCLUSIONS

Changes in the TSC can be quantified by sodium MR imaging at 7T and used to detect radiobiologic alterations in intracranial tumors at early time points after CyberKnife radiation therapy.

Sensitive electrochemiluminescence biosensor for glutathione using MnO2 nanoflower as novel co-reaction accelerator for Ru complex/tripropylamine system

In this work, MnO₂ nanoflower (NF), as novel and more effective co-reaction accelerator, was applied to construct a new ternary electrochemiluminescence (ECL) system of Ru complex/tripropylamine (TPrA)/MnO₂ NF. Compared with the classic Ru complex/TPrA binary ECL system, the reaction efficiency of co-reactant TPrA in the new ternary ECL system was obviously enhanced, leading to the significantly improved ECL signal by accelerating the dissociation of co-reactants into more active radicals. Then, an ECL biosensor was fabricated based on the proposed ternary ECL system, realizing the sensitive determination of glutathione (GSH). In order to realize the efficient nucleic acid amplification, a certain amount of GSH was firstly converted to a large number of intermediate DNA in assistance of Hg²⁺, which acted as walker could walk along with the DNA triplex immobilized on the electrode and cut off the DNA strand (S2) labeled with ferrocene (Fc). Owing to the fact that Fc possessed obvious quenching effect to the ECL of Ru complex labeled on the other side of S2, the ECL signal recovered significantly. Thus, the proposed ECL biosensor achieved the sensitive determination of GSH, and the detection limit was 50 nM.

A core-brush 3D DNA nanostructure: the next generation of DNA nanomachine for ultrasensitive sensing and imaging of intracellular microRNA with rapid kinetics

A highly loaded and integrated core–brush three-dimensional (3D) DNA nanostructure is constructed by programmatically assembling a locked DNA walking arm (DA) and hairpin substrate (HS) into a repetitive array along a well-designed DNA track generated by rolling circle amplification (RCA) and is applied as a 3D DNA nanomachine for rapid and sensitive intracellular microRNA (miRNA) imaging and sensing. Impressively, the homogeneous distribution of the DA and HS at a ratio of 1 : 3 on the DNA track provides a specific walking range for the DA to avoid invalid and random self-walking and notably improve the executive ability of the core–brush 3D DNA nanomachine, which easily solves the major technical challenges of traditional Au-based 3D DNA nanomachines: low loading capacity and low executive efficiency. As a proof of concept, the interaction of miRNA with the 3D DNA nanomachine could initiate the autonomous and progressive operation of the DA to cleave the HS for ultrasensitive ECL detection of target miRNA-21 with a detection limit as low as 3.57 aM and rapid imaging in living cells within 15 min. Therefore, the proposed core–brush 3D DNA nanomachine could not only provide convincing evidence for sensitive detection and rapid visual imaging of biomarkers with tiny change, but also assist researchers in investigating the formation mechanism of tumors, improving their recovery rates and reducing correlative complications. This strategy might enrich the method to design a new generation of 3D DNA nanomachine and promote the development of clinical diagnosis, targeted therapy and prognosis monitoring.

This study designed a highly loaded and integrated core–brush 3D DNA nanomachine for miRNA imaging and sensing, which easily solves the major technical challenges of traditional Au-based 3D nanomachines: low loading capacity and low executive efficiency.

Quadrilateral Nucleic Acid Frame-Accelerating DNAzyme Walker Kinetics for Biosensing Based on Host-Guest Recognition-Enhanced Electrochemiluminescence

Depending on the reaction between walkers and tracks, DNA walker is able to output signals continuously, which has attracted great attention from the bioanalytical community. Therefore, how to improve its reaction kinetics for efficient signal readout is of great significance. Herein, a quadrilateral DNAzyme walker was fabricated by colocalizing one walker and three DNA tracks in the quadrilateral nucleic acid frame to form a reaction unit (abbreviated as qDNA walker). Impressively, in contrast to the common free DNAzyme walker, the reaction kinetics of the qDNA walker was 2.3 times faster, which could achieve microRNA detection within 30 min. Meanwhile, an electrochemiluminescence (ECL) emitter of anthracene-cucurbituril supramolecular nanocrystals (Ant-CB SNCs) was obtained based on the self-assembly of cucurbituril (CB, host molecule) and anthracene (Ant, guest molecule). Benefiting from the host-guest recognition effect, the prepared Ant-CB SNCs exhibited enhanced ECL efficiency due to the supramolecular interaction between CB and Ant, which could inhibit vibration and rotation of the Ant molecules. We defined this new enhanced ECL phenomenon as "host-guest recognition-enhanced ECL." As a proof of concept, an ECL biosensor for microRNA-21 (miRNA-21) was constructed by combining the high-efficiency DNAzyme walker and the advanced ECL emitter of Ant-CB SNCs, which showed a linear range from 50 aM to 50 pM with a low limit of detection (11 aM), highlighting the great potential in clinical diagnosis.

MicroRNA-Triggered Deconstruction of Field-Free Spherical Nucleic Acid as an Electrochemiluminescence Biosensing Switch

Herein, a new field-free and highly ordered spherical nucleic acid (SNA) nanostructure was self-assembled directly by ferrocene (Fc)-labeled DNA tweezers and DNA linkers based on the Watson-Crick base pairing rule, which was employed as an electrochemiluminescence (ECL) quenching switch with improved recognition efficiency due to the high local concentration of the ordered nanostructure. Moreover, with a collaborative strategy combined with the advantages of both self-accelerated approach and pore confinement-enhanced ECL effect, the mesoporous silica nanospheres (mSiO₂ NSs) were prepared to be filled with rubrene (Rub) as ECL emitters and Pt nanoparticles (PtNPs) as coreaction accelerators (Rub-Pt@mSiO₂ NSs), which demonstrated high ECL response in the aqueous media (dissolved O₂ as coreactant). When the SNA nanostructure was immobilized on the Rub-Pt@mSiO₂ NSs-modified electrode, it presented a "signal off" state owing to the quenching effect of the Fc molecules. As a proof of concept, the SNA-based ECL switch platform was applied in the detection of microRNA let-7b (let-7b). Impressively, in the presence of the target let-7b, a deconstruction of the SNA nanostructure was actuated, causing the Fc to leave the electrode surface and achieved an extremely high ECL recovery ("signal on" state). Hence, a sensitive determination for let-7b was realized with a low detection limit of 1.8 aM ranging from 10 aM to 1 nM by employing the Rub-Pt@mSiO₂ NSs-based ECL platform combined with the target-triggered SNA deconstruction, which also offered an ingenious method for the further applications of biomarker analyses.

Programming a "Crab Claw"-like DNA Nanomachine as a Super Signal Amplifier for Ultrasensitive Electrochemical Assay of Hg2

Herein, with skillfully engaging stable T-Hg²⁺-T bonding, a "Crab Claw"-like DNA nanomachine with concise and highly efficient assembly and enhanced recognition/conversion efficiency was engineered as a super signal amplifier, which was united with Pd@Cu@Pt multimetallic mesoporous nanomaterials (Pd@Cu@Pt MMNs) for ultrasensitive electrochemical assay of mercury ions (Hg²⁺). Specifically, the formed "Crab Claw"-like DNA nanomachine could simultaneously trigger four same cascade DNAzyme cleavage reactions with the help of Mg²⁺ DNAzyme for markedly converting target Hg²⁺ to enormous DNA segments labeled with ferrocene (Fc), improving the detection sensitivity. Subsequently, the prepared Pd@Cu@Pt MMNs could not only show commendable electrochemical catalysis to Fc but also act as an excellent immobilization matrix for capturing and accumulating abundant Fc around them to further strengthen the electrochemical signal. As a result, the well-designed electrochemical sensor could achieve a low limit of detection of 3.58 fM in the range from 10 fM to 100 nM for Hg²⁺detection. This strategy offers a simple and rapid avenue to detect heavy metal ions and shows promising application potential for environmental pollutant monitoring.

Crystallization-Induced Enhanced Electrochemiluminescence from Tetraphenyl Alkene Nanocrystals for Ultrasensitive Sensing

Organic materials with diverse structures and brilliant glowing colors have been attracting extensive attention in optical electronic devices and electrochemiluminescence (ECL) fields and are currently faced with the issue of low ECL efficiency. Herein, a series of tetraphenyl alkene nanocrystals (TPA NCs) with an ordered molecular structure were synthesized to explore regularities in the crystallization-induced enhanced (CIE) ECL emission effects by altering the number and position of vinyl on the backbone of TPA molecules. Among those TPA NCs, tetraphenyl-1,3-butadiene (TPB) NCs exhibit the brightest ECL emission via a coreactant pathway, with the relative ECL efficiency of up to 31.53% versus the standard [Ru(bpy)₃]²⁺/TEA system, which is thousands of times higher than that of free TPB molecules. The high ECL efficiency of TPB NCs originates from the effective electron transfer of unique J-aggregates on the a axis of the nanocrystals to notably promote radiative transition and the restriction on the free rotation of TPB molecules to further suppress the nonradiative transition, which has exhibited great potential in ultrasensitive biosensing, efficient light-emitting devices, and clear ECL imaging fields. As a proof of concept, since dopamine (DA) can form benzoquinone species by electrochemical oxidation to realize intermediate radical quenching and excited-state quenching on the TPB NCs/TEA system, the TPB NCs with the CIE ECL effect are used to construct an ultrasensitive ECL-sensing platform for the determination of DA with a lower detection limit of 3.1 nM.

Engineering a high-efficient DNA amplifier for biosensing application based on perylene decorated Ag microflowers as novel electrochemiluminescence indicators

DNA-based amplifiers with high programmability and accurate molecular recognition ability have become a versatile platform for target amplification. However, the random diffusion of capture probes (CPs) in most DNA amplifiers limits the target recognition efficiency, affecting the limit of detection. Herein, a high-efficient DNA amplifier was developed by localizing the CPs consisted of the unique palindromic tails and target recognition sequences on Au nanoparticle modified magnetic beads (Au@MBs). In the presence of target K-ras gene, the CPs with high local concentration and orientation could capture the target efficiently to expose their palindromic tails, which could act as primers to trigger the polymerization for target recycling. More importantly, the polymerization products could involve in the next recycle and produce abundant mimic targets (MTs) continuously, thereby achieving the detection of trace K-ras gene. Meanwhile, a novel electrochemiluminescence (ECL) indicator of a thin-layer of perylene (Pe) molecules decorated Ag microflowers (Pe@Ag MFs) was obtained based on the reaction between the perylene cation radical (Pe^•+) and Ag atoms. The obtained Pe@Ag MFs exhibited desirable ECL performance because (i) a thin-layer of Pe molecules could reduce the inner filter effect and inactive emitters, (ii) the Ag MFs as coreaction accelerator could react with S₂O₈^2- to produce more SO₄^•- and shorten the distance between Pe^•- and SO₄^•- to significantly enhance the ECL intensity of Pe with less energy loss. This work paves the way for the development of efficient amplification strategy and offers a paradigm for the preparation of high-efficiency ECL indicators.