Luminescent Nanomaterials (II)

Ultrasensitive miRNA Detection Based on Magnetic Upconversion Nanoparticle Enhancement and CRISPR/Cas13a-Driven Signal Amplification

MicroRNAs (miRNAs), a class of small molecules with important regulatory functions, have been widely used in the field of biosensing as biomarkers for the early diagnosis of various diseases. Therefore, it is crucial to develop an miRNA detection platform with high sensitivity and specificity. Here, we have designed a CRISPR/Cas13-based enzymatic cyclic amplification system and regarded the magnetic upconversion nanoparticles (MUCNPs) as a biosensor of outputting the detection signal for the highly sensitive and high-fidelity detection of miRNAs. MUCNPs were composed of UCNPs (fluorescence donors) and Fe3O4@AuNPs (fluorescence acceptors) through double-stranded DNA hybrid coupling. The target miRNA acted as an activator, which could activate the trans-cleavage activity of Cas13a to the well-designed Trigger containing two uracil ribonucleotides (rU) in its loop and trigger a strand displacement reaction to generate a large amount of single-stranded DNA, resulting in the release of the UCNPs from MUCNPs. Benefiting from the high fidelity and high selectivity of CRISPR/Cas13a, the great effect of triggered enzymatic cycle amplification, and the high-intensity luminescent signal of MUCNPs, this method possessed miRNA detection capability with high sensitivity and specificity even in the complex environment with 10% fetal bovine serum (FBS) and a serum sample. Meanwhile, the detection limit could be as low as 83.2 fM. In addition, this method effectively reduced the effect of photobleaching and maintained high stability, which was expected to achieve efficient and sensitive miRNA detection.

Synthesis of Pyridin-1(2H)-ylacrylates and the Effects of Different Functional Groups on Their Fluorescence

While fluorescent organic materials have many potential as well as proven applications and so have attracted significant attention, pyridine-olefin conjugates remain a less studied subset of such systems. Herein, therefore, we report on the development of the straightforward syntheses of pyridin-1(2H)-ylacrylates and the outcomes of a study of the effects of substituents on their fluorescent properties. Such compounds were prepared using a simple, metal-free and three-component coupling reaction involving 2-aminopyridines, sulfonyl azides and propiolates. The fluorescent properties of the ensuing products are significantly affected by the positions of substituents on the cyclic framework, with those located in central positions having the greatest impact. Electron-withdrawing groups tend to induce blue shifts while electron-donating ones cause red shifts. This work highlights the capacity that the micro-modification of fluorescent materials provides for fine-tuning their properties such that they may be usefully applied to, for example, the study of luminescent materials.

Rapid detection of SARS-CoV-2: The gradual boom of lateral flow immunoassay

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is still in an epidemic situation, which poses a serious threat to the safety of people and property. Rapid diagnosis and isolation of infected individuals are one of the important methods to control virus transmission. Existing lateral flow immunoassay techniques have the advantages of rapid, sensitive, and easy operation, and some new options have emerged with the continuous development of nanotechnology. Such as lateral flow immunoassay test strips based on colorimetric-fluorescent dual-mode and gold nanoparticles, Surface Enhanced Raman Scattering, etc., these technologies have played an important role in the rapid diagnosis of COVID-19. In this paper, we summarize the current research progress of lateral flow immunoassay in the field of Severe Acute Respiratory Syndrome Coronavirus 2 infection diagnosis, analyze the performance of Severe Acute Respiratory Syndrome Coronavirus 2 lateral flow immunoassay products, review the advantages and limitations of different detection methods and markers, and then explore the competitive CRISPR-based nucleic acid chromatography detection method. This method combines the advantages of gene editing and lateral flow immunoassay and can achieve rapid and highly sensitive lateral flow immunoassay detection of target nucleic acids, which is expected to be the most representative method for community and clinical point-of-care testing. We hope that researchers will be inspired by this review and strive to solve the problems in the design of highly sensitive targets, the selection of detection methods, and the enhancement of CRISPR technology, to truly achieve rapid, sensitive, convenient, and specific detection of novel coronaviruses, thus promoting the development of novel coronavirus diagnosis and contributing our modest contribution to the world's fight against epidemics.

Recent Advances in Nano-Formulations for Skin Wound Repair Applications

Skin injuries caused by accidents and acute or chronic diseases place a heavy burden on patients and health care systems. Current treatments mainly depend on preventing infection, debridement, and hemostasis and on supplementing growth factors, but patients will still have scar tissue proliferation or difficulty healing and other problems after treatment. Conventional treatment usually focuses on a single factor or process of wound repair and often ignores the influence of the wound pathological microenvironment on the final healing effect. Therefore, it is of substantial research value to develop multifunctional therapeutic methods that can actively regulate the wound microenvironment and reduce the oxidative stress level at the wound site to promote the repair of skin wounds. In recent years, various bioactive nanomaterials have shown great potential in tissue repair and regeneration due to their properties, including their unique surface interface effect, small size effect, enzyme activity and quantum effect. This review summarizes the mechanisms underlying skin wound repair and the defects in traditional treatment methods. We focus on analyzing the advantages of different types of nanomaterials and comment on their toxicity and side effects when used for skin wound repair.