Research advances in Zein-based nano-delivery systems.

Zein is the main vegetable protein from maize. In recent years, Zein has been widely used in pharmaceutical, agriculture, food, environmental protection, and other fields because it has excellent biocompatibility and biosafety. However, there is still a lack of systematic review and research on Zein-based nano-delivery systems. This paper systematically reviews preparation and modification methods of Zein-based nano-delivery systems, based on the basic properties of Zein. It discusses the preparation of Zein nanoparticles and the influencing factors in detail, as well as analyzing the advantages and disadvantages of different preparation methods and summarizing modification methods of Zein nanoparticles. This study provides a new idea for the research of Zein-based nano-delivery system and promotes its application.

Electrogenerated chemiluminescence biosensor for microRNA detection incorporating enzyme-free dual DNA cyclic amplification and Ru(bpy)32+-functionalized metal-organic framework.

Herein, a novel electrogenerated chemiluminescence (ECL) biosensor for the determination of microRNA was developed on the basis of enzyme-free dual signal amplification and Ru(bpy)32+-functionalized metal-organic frameworks (Ru@MIL-101(Al)-NH2) as ECL signal labels. MicroRNA-21 (miRNA-21) was used as a model target, which initiated the toehold-mediated strand displacement reaction (TSDR). The first cyclic amplification TSDR converted a small quantify of miRNA-21 to abundant report strands (RS), which then catalyzed the second cyclic amplification catalytic hairpin assembly (CHA). The CHA ran cyclically to produce numerous H1-H2 duplexes with the exposed segment. Finally, the newly exposed segment of H2 could bind with the ECL probe (DNA-Ru@MIL-101(Al)-NH2), leading to an evident ECL signal enhancement. The results showed that the ECL intensity varied linearly with the logarithm of the concentration of miRNA-21 ranging from 0.01 to 10,000 pM. The detection limit was as low as 4 fM because of the signal amplification through TSDR and CHA processes coupling with Ru@MIL-101(Al)-NH2. In addition, this biosensor has been successfully applied to detect miRNA-21 in MCF-7 cells, providing great potential for the related clinical diagnosis.

Signal-on electrogenerated chemiluminescence biosensor for ultrasensitive detection of microRNA-21 based on isothermal strand-displacement polymerase reaction and bridge DNA-gold nanoparticles.

MicroRNA-21 (miRNA-21) is a promising diagnostic biomarker for breast cancer screening and disease progression. A sensitive and selective strategy for the quantitative determination of miRNA-21 is of great significance in the early diagnosis of cancers. Herein, a novel electrogenerated chemiluminescence (ECL) biosensor was designed for the detection of miRNA-21 with dual signal amplification based on isothermal strand-displacement polymerase reaction (ISDPR) and bridge DNA-gold nanoparticles (AuNPs) nanocomposites. The ECL biosensor was fabricated by self-assembling a thiolated capture probe (SH-CP) on the surface of a gold electrode. The target miRNA-21 initiated the phi29 DNA polymerase-mediated ISDPR, which could generate large numbers of single-stranded DNA (assistant DNA) with accurate and comprehensive nucleotide sequences. The assistant DNA was captured by the SH-CP self-assembled on the Au electrode and further hybridized with bridge DNA-AuNPs nanocomposites, more biotins can be captured on the electrode surface. Afterward, a streptavidin-modified Ru (bpy)32+ complex (SA-Ru) was bound to the bridge DNA-AuNPs nanocomposites via a specific interaction between biotin and streptavidin to produce a strong ECL signal. The ECL intensity was logarithmically proportion to the concentration of target miRNA-21 over a range from 0.01 fM to 10,000 fM with a detection limit of 3.2 aM. The proposed ECL biosensor was successfully applied to detect miRNA-21 in total RNA samples extracted from human breast cancer cells, and it showed great potential for early cancer diagnosis based on miRNA as a biomarker.

Signal-Off Electrogenerated Chemiluminescence Biosensing Platform Based on the Quenching Effect between Ferrocene and Ru(bpy)32+-Functionalized Metal-Organic Frameworks for the Detection of Methylated RNA.

N6-methyladenine (m6A), one of the most common chemical modifications of eukaryotic RNA, participates in many important biological processes. An effective strategy for the quantitative determination of m6A is of great significance. Herein, we used methylated microRNA-21 (miRNA21) as the model target to propose a simple and sensitive electrogenerated chemiluminescence (ECL) biosensing platform to detect a specific m6A RNA sequence. This strategy is based on the fact that the anti-m6A-antibody can specifically recognize and bind to the m6A site in the RNA sequence, resulting in a quenching effect between Ru(bpy)32+-functionalized metal-organic frameworks and ferrocene. Luminescent metal-organic frameworks (Ru@MOFs) not only act as ECL indicators but also serve as nanoreactors for the relative ECL reactions owing to their porous or multichannel structure, which overcomes the fact that Ru(bpy)32+ is easily released when used for aqueous-phase detection, thus enhancing the ECL efficiency. Moreover, the ECL method has fewer modification steps and uses only one antibody to recognize the target RNA sequence, which simplifies the operation process and reduces the detection time, presenting a wide linear range (0.001-10 nM) for m6A RNA determination with a low detection limit (0.0003 nM). Additionally, this developed strategy was validated for m6A RNA detection in human serum. Thus, the ECL biosensing method provides a new method for m6A RNA determination that is simple, highly specific, and sensitive.