Characterization of a recombinant Aspergillus niger GZUF36 lipase immobilized by ionic liquid modification strategy.

Enzyme immobilized on magnetic nanomaterials is a promising biocatalyst with efficient recovery under applied magnets. In this study, a recombinant extracellular lipase from Aspergillus niger GZUF36 (PEXANL1) expressed in Pichia pastoris GS115 was immobilized on ionic liquid-modified magnetic nano ferric oxide (Fe3O4@SiO2@ILs) via electrostatic and hydrophobic interaction. The morphology, structure, and properties of Fe3O4@SiO2@ILs and immobilized PEXANL1 were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, vibration sample magnetometer, and zeta potential analysis. Under optimized conditions, the immobilization efficiency and activity recovery of immobilized PEXANL1 were 52 ± 2% and 122 ± 2%, respectively. The enzymatic properties of immobilized PEXANL1 were also investigated. The results showed that immobilized PEXANL1 achieved the maximum activity at pH 5.0 and 45 °C, and the lipolytic activity of immobilized PEXANL1 was more than twice that of PEXANL1. Compared to PEXANL1, immobilized PEXANL1 exhibited enhanced tolerance to temperature, metal ions, surfactants, and organic solvents. The operation stability experiments revealed that immobilized PEXANL1 maintained 86 ± 3% of its activity after 6 reaction cycles. The enhanced catalytic performance in enzyme immobilization on Fe3O4@SiO2@ILs made nanobiocatalysts a compelling choice for bio-industrial applications. Furthermore, Fe3O4@SiO2@ILs could also benefit various industrial enzymes and their practical uses. KEY POINTS: • Immobilized PEXANL1 was confirmed by SEM, FT-IR, and XRD. • The specific activity of immobilized PEXANL1 was more than twice that of PEXANL1. • Immobilized PEXANL1 had improved properties with good operational stability.

Effect of freeze-dried protectants on the survival rate and fermentation performance of fermented milk's directed vat set starters.

A directed vat set (DVS) starter was proposed to improve the drawbacks of liquid starters in fermented production and enhance the survival rates of B. animalis subsp. lactis BZ11, S. thermophilus Q-1, and Lactiplantibacillus plantarum LB12. The protective agent formula was optimized using the response surface method (RSM), with the survival rate as the benchmark. The best combination of cryoprotectants was determined to be BZ11: 10 % skimmed milk powder, 3 % sodium glutamate, and 15 % trehalose; LB12: 10 % skim milk powder, 5 % glutamate sodium, and 10 % trehalose; Q-1: 10 % skimmed milk powder, 3 % sodium glutamate, and 10 % trehalose. The survival rate of BZ11 significantly increased to 92.87 ± 1.25 %. The DVS fermented milk did not differ significantly from the control group regarding cholesterol removal, live cell counts and pH (p > 0.05). All DVS can be stored for at least 2500 d at -20 °C-this DVS starter for fermented milk benefits from its large-scale and automated commercial production.

Elimination of surface/subsurface defects on additively manufactured AlSi10Mg mirrors through nano-second laser irradiation.

Metal mirrors have attracted increasing attention for satisfying the growing demands for high-performance optics in airborne and spaceborne remote sensing systems. Additive manufacturing has enabled the development of metal mirrors with reduced weight and improved strength. AlSi10Mg is the most widely used metal for additive manufacturing. Diamond cutting is an effective method for obtaining nanometer-scale surface roughness. However, the surface/subsurface defects of additively manufactured AlSi10Mg deteriorate the surface roughness. Conventionally, AlSi10Mg mirrors used in near-infrared and visible systems are plated with NiP layers to improve the surface polishing performance; however, this leads to the bimetallic bending because of the different coefficients of thermal expansion between the NiP layers and AlSi10Mg blanks. In this study, a method of nanosecond-pulsed laser irradiation is proposed to eliminate the surface/subsurface defects of AlSi10Mg. The microscopic pores, unmolten particles and two-phase microstructure of the mirror surface were eliminated. The mirror surface exhibited better polishing performance, and it could be smoothly polished to a nanometer-scale surface roughness. The mirror exhibits strong temperature stability owing to the elimination of the bimetallic bending caused by the NiP layers. It is expected that the mirror surface fabricated in this study can satisfy the requirements for near-infrared or even visible applications.

Sparse-aperture photonics-integrated interferometer (SPIN) imaging system: structural design and imaging quality analysis.

The burgeoning field of astrophotonics, the interface between astronomy and photonics, is redefining astronomical instrumentation to replace traditional bulk optical systems with integrated optics. This drives the development of a new promising photonics-integrated interferometric imaging technique, called the segmented planar imaging detector for electro-optical reconnaissance (SPIDER). Compared to conventional imaging systems, SPIDER can reduce the size, weight, and power (SWaP) by one to two orders of magnitude for an equivalent imaging resolution in virtue of photonics-integrated technology. However, SPIDER has a dense lens distribution and tens of separated narrow wavebands demultiplexed by array waveguide gratings. In this paper, we developed a new simplified sparse-aperture photonics-integrated interferometer (SPIN) imaging system. The SPIN imaging system was no more a Michelson configuration interferometer as SPIDER and was designed as a Fizeau configuration interferometer imaging system. This transfer of configuration type affords a more concise structure; the SPIN was designed with much less apertures and fewer wavebands than those of SPIDER. Further, the SPIN yields enhanced modulation transfer function and imaging quality with equivalent aperture diameter, compared with SPIDER. The main barrier of this transfer is the elimination of coupling restriction at the tip of a waveguide, namely the apodization effect. This effect, which is caused by the coupling effect between Fourier lens and waveguide, hinders SPIN imaging systems from getting finer resolution. However, a microscope could be used to eliminate this effect. Moreover, a waveguide array is used to receive these finer details and enlarges the field of view in SPIN. The coupling efficiency of the waveguides and crosstalk errors between waveguides of array were analyzed, which are important for proper parameters setting in SPIN imaging system. Based on these analyses, the imaging principle was derived and a hyper-Laplacian-based imaging reconstruction algorithm was developed. A simulation of the SPIN imaging system with seven apertures and one imaging waveband demonstrated the high imaging quality.

Effect of cross-linked enzyme aggregate strategy on characterization of sn-1,3 extracellular lipase from Aspergillus niger GZUF36.

The sn-1,3 extracellular lipase from Aspergillus niger GZUF36 (EXANL1) has important potential applications. The cross-linked enzyme aggregate (CLEA) of purified EXANL1 (CLEA-EXANL1) achieved optimum activity recovery (148.5 ± 0.9%), immobilization yield (100 ± 0%), and recovered activity (99.7 ± 0.6%) with 80% tert-butanol as the precipitant, glutaraldehyde (GA) concentration of 30 mM, GA treatment time of 1.5 h, and centrifugal speed of 6000×g. The effect of CLEA strategy on the characterization of EXANL1 was evaluated in this work. CLEA-EXANL1 exhibited a broader optimum pH range (4-6) compared with free EXANL1 (6.5). CLEA-EXANL1 presented optimum activity at 40 °C, which was 5 °C higher than that of free EXANL1. CLEA strategy decreased the maximum reaction rate and increased the Michaelis-Menten constant of EXANL1 when olive oil emulsion was used as a substrate. Moreover, after 30 days, free EXANL1 lost more than 80.0% of its activity, whereas CLEA-EXANL1 retained more than 90.0% of its activity. CLEA strategy improved the tolerance of EXANL1 in polar organic solvents. Fourier transform infrared spectroscopy results showed that the CLEA technique increased the contents of ß-sheets and ß-turns in EXANL1 and reduced those of α-helixes and irregular crimps. CLEA strategy caused no change in the sn-1,3 selectivity of EXANL1. Therefore, EXANL1 in the form of CLEA is a valuable catalyst in the synthesis of 1,3-diacylglycerol. KEY POINTS: • Cross-linked enzyme aggregate (CLEA) strategy broadened the optimum pH range of sn-1,3 extracellular lipase from Aspergillus niger GZUF36 (EXANL1). • CLEA strategy improved the tolerance of EXANL1 in polar organic solvents. • CLEA strategy caused no change in the positional selectivity of EXANL1.

Co-expression analysis provides important module and pathways of human dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a heart disease that injured greatly to the people wordwide. Systemic co-expression analysis for this cancer is still limited, although massive clinic experiments and gene profiling analyses had been well performed previously. Here, using the public RNA-Seq data "GSE116250" and gene annotation of Ensembl database, we built the co-expression modules for DCM by Weighted Gene Co-Expression Network Analysis, and investigated the function enrichment and protein-protein interaction (PPI) network of co-expression genes of each module by Database for Annotation, Visualization, and Integrated Discovery and Search Tool for the Retrieval of Interacting Genes/Proteins database, respectively. First, 5,000 genes in the 37 samples were screened and 11 co-expression modules were conducted. The number of genes for each module ranged from 77 to 936, with a mean of 455. Second, interaction relationships of hub-genes between pairwise modules showed great differences, suggesting relatively high-scale independence of the modules. Third, functional enrichments of the co-expression modules exhibited great differences. We found that genes in module 3 were significantly enriched in the pathways of focal adhesion and ubiquitin-mediated proteolysis. This module was inferred as the key module involved in DCM. In addition, PPI analysis revealed that the genes HSP90AA1, CTNNB1, MAPK1, GART, and PPP2CA owned the largest number of adjacency genes, unveiling that they may function importantly during the occurrence of DCM. Focal adhesion and ubiquitin-mediated proteolysis play important roles in human DCM.

Equivalent thin-plate method for stressed mirror polishing of an off-axis aspheric silicon carbide lightweight mirror.

No physical model of stressed mirror polishing, based on the small deflection and deformation of elastic thin plates, has been applied in processing lightweight mirrors. We propose an equivalent thin-plate method for the stressed loading of lightweight mirrors for the first time. Stressed loading and polishing of an aspheric lightweight mirror are simulated using the small-deflection deformation theory of an elastic thin plate. We simulate off-axis aspheric silicon carbide (SiC) lightweight mirrors with three different structures, determining the corresponding equivalent thickness plate in a lightweight structure with a nearly uniform surface density distribution and isotropic bending properties. We then establish a residual removal model of a stressed polishing surface, design the stressed loading equipment, and propose an iterative method for stressed polishing of an off-axis aspheric SiC lightweight mirror. The results demonstrate that it is feasible to choose a lightweight structure that performs full-aperture stressed polishing on off-axis aspheric lightweight mirrors consisting of SiC or other materials.

Effects of different strains and fermentation method on nattokinase activity, biogenic amines, and sensory characteristics of natto.

Nattokinase activity (NK), biogenic amine content and sensory properties of natto are of great significance to consumers, which are affected by strains and fermentation methods. In this study, changes in the pH, biogenic amine and free amino nitrogen (FAN) contents, NK and protease activities, and sensory characteristics of natto prepared using Bacillus subtilis GUTU09 combined with different strains (Lactobacillus, Bifidobacterium and Mucor) and fermentation methods were investigated. The combination of two strains showed the best fermentation performance among all samples. The NK and protease activity and FAN content in double-strain fermentation increased by 10.33 FU/g, 88.78 U/g, and 2.34 g/kg, respectively, compared with those in single-strain fermentation. Sensory evaluation demonstrated that mixed fermentation primarily affected the sensory acceptance. This method also reduced the contents of various biogenic amines in natto compared with single-strain fermentation. Tyramine, cadaverine, spermine, and spermidine were significantly reduced, whereas histamine was slightly increased. The total biogenic amines decreased from 390.76 mg/kg to a minimum of 16.16 mg/kg. Some Mucor strains also reduced the contents of various biogenic amines. In the dual-bacteria fermentation of Mucor and GUTU09, co-fermentation has advantages over stage-fermentation, with higher NK and protease activity and higher sensory scores. Correlation analysis showed that the formation and accumulation of some biogenic amines in natto prepared using different microbial combinations were related to NK activity and pH. All these results showed that the quality of natto was improved by mixed fermentation and suitable fermentation methods, which laid a foundation for its potential industrial application.

Gene cloning, expression, purification and characterization of a sn-1,3 extracellular lipase from Aspergillus niger GZUF36.

Sn-1,3 extracellular Aspergillus niger GZUF36 lipase (EXANL1) has wide application potential in the food industry. However, the A. niger strain has defects such as easy degradation and instability in the expression of sn-1,3 lipase. To obtain a stable expression of this lipase and its subsequent enzymatic properties, the gene encoding EXANL1 was cloned and expressed in Escherichia coli BL21 (DE3) cells using pET-28a as the expression vector. The temperature-induced conditions were optimized, and we successfully achieved its active expression in E. coli. These conditions significantly influenced the active expression of EXANL1 (P < 0.05), and the highest enzyme activity of the supernatant of lysis cells expressed at 20 °C was at 7.02 ± 0.05 U/mL. The expressed recombinant EXANL1 was purified using Ni-NTA, showing an estimated relative molecular mass of 35 kDa. The recombinant EXANL1 exhibited maximum activity at 35 °C and pH 4.0, with a wide acid pH range. Thin-layer chromatography analysis showed that the enzyme displayed sn-1,3 positional selectivity toward triolein. The recombinant EXANL1 could maintain its relative activities (> 80%) after 24 h of incubation at pH 3-10, suggesting its suitability for a wide range of industrial applications. After comparing these properties with those of the other A. niger lipases, we found that some key amino acids may play a decisive role in enzymology. This work laid a foundation for the stable expression of the EXANL1 gene and its potential industrial application.

Experimental study on hybrid compensation testing of an off-axis convex ellipsoid surface.

Aspherical surfaces can provide significant benefits to a wide variety of optical systems, but manufacturing high-precision aspherical surfaces has historically been limited by the ability to measure them. Null testing has always been the ideal method in aspherical measurement. However, in many cases, it is hard to realize null testing for complex surfaces, especially for convex surfaces in complicated forms. In this paper, we propose a hybrid compensation method combining a spherical mirror and a computer generated hologram (CGH) to achieve the null testing of the convex aspherical surface. Firstly, we introduce our self-developed mathematical models in the hybrid compensation method, including optics alignment model, distortion correction model and spherical surface error removing model. Then the performance of our proposed method is analyzed by a null testing experiment of an off-axis convex ellipsoid mirror. The experimental result shows that the proposed method can accomplish the hybrid compensation testing of convex aspherical surfaces effectively, and it can also bring much to the application of our method in convex aspherical surface testing.

Distortion measurement of optical system using phase diffractive beam splitter.

Traditional methods for distortion measurement of large-aperture optical systems are time-consuming and ineffective because they require each field of view to be individually measured using a high-precision rotating platform. In this study, a new method that uses a phase diffractive beam splitter (DBS) is proposed to measure the distortion of optical systems, which has great potential application for the large-aperture optical system. The proposed method has a very high degree of accuracy and is extremely economical. A high-precision calibration method is proposed to measure the angular distribution of the DBS. The uncertainty analysis of the factors involved in the measurement process has been performed to highlight the low level of errors in the measurement methodology. Results show that high-precision measurements of the focal length and distortion were successfully achieved with high efficiency. The proposed method can be used for large-aperture wide-angle optical systems such as those used for aerial mapping applications.

Measurement of rotationally symmetric aspherical surfaces with the annular subaperture stitching method.

The annular subaperture stitching method is an effective method for testing rotationally symmetric aspherical surfaces. To create a full aperture map of this kind of asphere, we propose an annular subaperture stitching algorithm. The algorithm is based on triangulation interpolation theory, least-square fitting method, and ray tracing method. We first show the principle of our stitching algorithm. Then, the performance of the proposed method is analyzed by simulation testing to evaluate the accuracy of the above algorithm. In the end, the experiment is given to demonstrate the correctness of our method. Both the simulation and experiment results show that the introduced method is quite effective for the testing of rotationally symmetric aspherical surfaces.

Influence of different parameters on reverse micelle extraction combined with acetone precipitation to purify sn-1,3 extracellular lipase from Aspergillus niger GZUF36.

There are few reports on the feasibility of combined reverse micelle extraction and acetone precipitation to obtain electrophoretic pure enzymes. We aimed to purify a sn-1,3 extracellular lipase from a novel Aspergillus niger GZUF36 through this combination in this work. This lipase preliminarily purified by controlling the volume ratio (1:2.5) of crude enzyme solution and acetone. Then, we studied effects of different parameters on reverse micelle extraction. The suitable surfactant, pH, salt and cosolvent and extraction time for forward extraction were 125 mM cetyl trimethylammonium bromide (CTAB), 9.0, 0.075 M NaCl, 10% n-hexanol and 30 min, respectively. Under these conditions, the forward extraction rate reached 90.3% ± 3.2%. The suitable salt, pH, extraction time and short chain alcohol for backward extraction were consecutively 1.5 M KCl, 6.5, 60 min and 10% ethanol. Adding 10% ethanol shows a significant advantage of improvement the extraction rate. Under these optimal conditions, the total extraction rate and purification factor of lipase reached 76.8% and 10.14, respectively. SDS-PAGE showed that molecular weight of the pure protein was 42.7 kDa and TLC exhibited sn-1,3 selectivity of this lipase. LC-MS/MS analysis revealed that the lipase had 297 amino acid residues and was likely to glycosylate. Through the study of different parameters, it demonstrated that the new and simple combination of reverse micelle extraction using CTAB as surfactant and n-hexanol as cosolvent for forward extraction and adding ethanol for backward extraction and acetone precipitation is a promising method to get almost an electrophoretically pure sn-1,3 lipase.

Influences of pulsed light-UV treatment on the storage period of dry-cured meat and shelf life prediction by ASLT method.

In order to prolong the shelf life of Chinese traditional dry-cured meat products, a pulsed ultraviolet light (PL-UV) irradiation method was adopted to treat meat products according to the following parameters: pulse energy of 8 J, 300 pulses, and an effective exposure distance of 10 cm; the UV light irradiation power of 6 W, an effective exposure distance of 11 cm, and an exposure period of 5 min. After a pulsed ultraviolet irradiation, total bacterial count in dry-cured meat decreased from 6.89 to 4.53 lg (CFU/g). The number of Micrococcus and Staphylococcus in samples decreased from 6.49 to 4.10 lg (CFU/g) and the number of molds and yeasts decreased from 5.45 to 4.28 lg (CFU/g). The number of Lactic acid bacteria increased from 3.97 to 4.55 lg (CFU/g) and Escherichia coli was not detected. Total colonies, target bacteria, peroxide value, thiobarbituric acid-reactive substances, water activity, T 2 relaxation time, pH, color difference, total volatile basic nitrogen, and the sensory evaluations of dry-cured meat products after PL-UV treatments were determined in a 30-d storage experiment. The shelf life of dry-cured meat treated with PL-UV irradiation at 20 °C was predicted to reach to 294 d by applying of shelf life testing method accelerated. The quality and safety of dry-cured meat treated with PL-UV irradiation was better than that of untreated samples.

Effects of organic solvent, water activity, and salt hydrate pair on the sn-1,3 selectivity and activity of whole-cell lipase from Aspergillus niger GZUF36.

We previously screened a whole-cell lipase EC 3.1.1.3 from the novel strain Aspergillus niger GZUF36, which exhibited 1,3-selectivity in the synthesis of 1,3-diacylglycerol via glycerolysis. However, the mechanism of lipase selectively in catalyzing the sn-1,3 position remains ambiguous. This work was performed to investigate the 1,3-selective mechanism of lipase using glycerolysis to synthesize 1,3-diacylglycerol (1,3-DG) as a model reaction by changing solvent(s) and water activity (aw), and addition of salt hydrate pair. The measured diacylglycerol yield was also used to examine lipase activity. Results indicated that not only organic solvent and aw have strong effect on the sn-1,3 selectivity, but also ions of salt hydrate pair also affected selectivity. Lipase conformation was altered by hydrophobic interactions of the solvent, aw, or ions of salt hydrate, resulting in distinct sn-1,3 selectivity of the lipase. The salt hydrate pair changed the lipase conformation and selectivity not only by aw but also by static interactions, which was rarely reported. These parameters also affected lipase activity. The lipase displayed the highest selectivity (about 88%) and activity in solvents of t-butanol and n-hexane (1:29, v/v) at aw 0.43. The results demonstrated that the sn-1,3 selectivity and activity of the lipase from A. niger GZUF36 may be improved by control of some crucial factors. This work laid a foundation for the application of lipase in the synthesis of 1,3-DG and other structural and functional lipids.

Mapping distortion correction in freeform mirror testing by computer-generated hologram.

Distortion can be introduced in null testing using computer-generated holograms for off-axis aspheres or freeforms with significant deviation. It leads to the failure of testing results to guide deterministic optical processing. In this paper, based on ray tracing and calibration marks applied to a mirror surface, a high-accuracy method is proposed to correct the distortion. The correction error is less than 1 mm. Second and fourth mirrors of a reflective telescope prototype with an F number of 6.5 and field of view of 76° are polished. In the process, distortion is corrected, and the position misalignment error is as small as 0.783 mm. For the sake of alignment, the two mirrors are fixed on a 790 mm×390 mm SiC substrate. The root-mean-square value of the mirror surface error is 0.0433λ (λ=0.6328 µm) after ion beam finishing.

Large-aperture space optical system testing based on the scanning Hartmann.

Based on the Hartmann testing principle, this paper proposes a novel image quality testing technology which applies to a large-aperture space optical system. Compared with the traditional testing method through a large-aperture collimator, the scanning Hartmann testing technology has great advantages due to its simple structure, low cost, and ability to perform wavefront measurement of an optical system. The basic testing principle of the scanning Hartmann testing technology, data processing method, and simulation process are presented in this paper. Certain simulation results are also given to verify the feasibility of this technology. Furthermore, a measuring system is developed to conduct a wavefront measurement experiment for a 200 mm aperture optical system. The small deviation (6.3%) of root mean square (RMS) between experimental results and interferometric results indicates that the testing system can measure low-order aberration correctly, which means that the scanning Hartmann testing technology has the ability to test the imaging quality of a large-aperture space optical system.

Edge control in a computer controlled optical surfacing process using a heterocercal tool influence function.

Edge effect is regarded as one of the most difficult technical issues in a computer controlled optical surfacing (CCOS) process. Traditional opticians have to even up the consequences of the two following cases. Operating CCOS in a large overhang condition affects the accuracy of material removal, while in a small overhang condition, it achieves a more accurate performance, but leaves a narrow rolled-up edge, which takes time and effort to remove. In order to control the edge residuals in the latter case, we present a new concept of the 'heterocercal' tool influence function (TIF). Generated from compound motion equipment, this type of TIF can 'transfer' the material removal from the inner place to the edge, meanwhile maintaining the high accuracy and efficiency of CCOS. We call it the 'heterocercal' TIF, because of the inspiration from the heterocercal tails of sharks, whose upper lobe provides most of the explosive power. The heterocercal TIF was theoretically analyzed, and physically realized in CCOS facilities. Experimental and simulation results showed good agreement. It enables significant control of the edge effect and convergence of entire surface errors in large tool-to-mirror size-ratio conditions. This improvement will largely help manufacturing efficiency in some extremely large optical system projects, like the tertiary mirror of the Thirty Meter Telescope.

Impact of Ganoderma lucidum fermentation on the nutritional composition, structural characterization, metabolites, and antioxidant activity of Soybean, sweet potato and Zanthoxylum pericarpium residues.

One of the major issues in the food sector is the lack of resource utilization and the contamination of the environment caused by by-products. This study aimed to investigate the effects of Ganoderma lucidum (GL) fermentation on the nutritional components, structural characterization, metabolites, and antioxidant activity of soybean residue (SR), sweet potato residue (SPR), and zanthoxylum pericarpium residue (ZPR). The results showed that the nutrient contents of SR, SPR and ZPR increased. The active substances, amino acids (umami, aromatic and basic), metabolites and antioxidant activity (DPPH, ABTS, FRAP) (SR and SPR increased by 11.43, 32.64, 40.19 µmol Trolox/100 g and 19.29, 17.7, 32.35 µmol Trolox/100 g, respectively) of SR and SPR were increased. However, the results of ZPR showed a decrease in the content of bioactive substances, amino acids, and antioxidant activity. The results show that using GL fermentation can provide novel ideas and theoretical basis for improving SR and SPR to obtain new raw materials for antioxidant products.

Blood miRNAs as Potential Diagnostic Biomarkers for Chronic Obstructive Pulmonary Disease: A Meta-Analysis.

Purpose: Investigate the efficacy of blood microRNAs (miRNAs) as diagnostic biomarkers for Chronic Obstructive Pulmonary Disease (COPD). Patients and Methods: We conducted a comprehensive search in English and Chinese databases, selecting studies based on predetermined criteria. Diagnostic parameters like summarized sensitivity (SSEN), summarized specificity (SSPE), summarized positive likelihood ratio (SPLR), summarized negative likelihood ratio (SNLR), and diagnostic odds ratio (DOR), and area under the curve (AUC) of the summary receiver operating characteristic (SROC) curves were analyzed using a bivariate model. Each parameter was accompanied by a 95% confidence interval (CI). Results: Eighteen high-quality studies were included. For diagnosing COPD with blood miRNAs, the SSEN was 0.83 (95% CI 0.76-0.89), SSPE 0.76 (95% CI 0.70-0.82), SPLR 3.50 (95% CI 2.66-4.60), SNLR 0.22 (95% CI 0.15-0.33), DOR 15.72 (95% CI 8.58-28.77), and AUC 0.86 (95% CI 0.82-0.88). In acute exacerbations, SSEN was 0.85 (95% CI 0.76-0.91), SSPE 0.80 (95% CI 0.73-0.86), SPLR 4.26 (95% CI 3.05-5.95), SNLR 0.19 (95% CI 0.12-0.30), DOR 22.29 (95% CI 11.47-43.33), and AUC 0.89 (95% CI 0.86-0.91). Conclusion: Blood miRNAs demonstrate significant accuracy in diagnosing COPD, both in general and during acute exacerbations, suggesting their potential as reliable biomarkers.