Polyethyleneimine-mediated assembly of DNA nanotubes for KRAS siRNA delivery in lung adenocarcinoma therapy.

Self-assembled DNA nanostructures hold great promise in biosensing, drug delivery and nanomedicine. Nevertheless, challenges like instability and inefficiency in cellular uptake of DNA nanostructures under physiological conditions limit their practical use. To tackle these obstacles, this study proposes a novel approach that integrates the cationic polymer polyethyleneimine (PEI) with DNA self-assembly. The hypothesis is that the positively charged linear PEI can facilitate the self-assembly of DNA nanostructures, safeguard them against harsh conditions and impart them with the cellular penetration characteristic of PEI. As a demonstration, a DNA nanotube (PNT) was successfully synthesized through PEI mediation, and it exhibited significantly enhanced stability and cellular uptake efficiency compared to conventional Mg2+-assembled DNA nanotubes. The internalization mechanism was further found to be both clathrin-mediated and caveolin-mediated endocytosis, influenced by both PEI and DNA. To showcase the applicability of this hybrid nanostructure for biomedical settings, the KRAS siRNA-loaded PNT was efficiently delivered into lung adenocarcinoma cells, leading to excellent anticancer effects in vitro. These findings suggest that the PEI-mediated DNA assembly could become a valuable tool for future biomedical applications.

A Study on the Bond-Slip Relationship of the CFRP-Steel Interface of CFRP Strengthened Steel.

The bonding interface between the CFRP and the steel plate is the weak link of CFRP-strengthened steel structures. This paper studies the bond-slip relationship of the CFRP-steel interface by experiments and numerical tests. First, a series of double-strap experiments on a CFRP-strengthened steel plate are carried out. The results show that the maximum shear stress of the bonding interface of the Q345B specimen is larger than that of the X100 specimen. The initial slip and maximum slip become larger as the thickness of the bonding interface becomes larger. Finite element analysis of the above tests is carried out; we introduce the maximum stress criterion to simulate the bonding interface, which assumes that when the nominal stress of the material reaches the maximum nominal stress of damage, the material begins to damage. The FE model established has proved very effective for analyzing the bond characteristics of CFRP-strengthened steel plates. Finally, a verification test was carried out, using an FE analysis to verify the accuracy of the modified equations; the results prove that the results of the modified equations are in good agreement with the numerical results and experiment results, which verifies the effectiveness of the equations.

Detection of trace mercury ions in water with a bovine-serum-albumin-modified Au@SiNWA surface-enhanced-Raman-scattering sensor.

Accurate detection of mercury ions (Hg2+) in water is of great importance for environmental protection. Here, a surface-enhanced Raman scattering (SERS) sensor using bovine-serum-albumin-modified gold-silicon nanowire arrays (Au@SiNWAs) is used to detect the ions. The SiNWAs were grown via chemical etching; the addition of modified gold particles on the surface formed Au@SiNWAs to increase the surface activity. The Raman enhancement factor was as large as ∼2.52 × 105, which was also confirmed with finite-difference time-domain simulations. The detection limit for Hg2+ ions in water was as low as ∼10-12 M, which is much lower than that stipulated by the United States Environmental Protection Agency's maximum residue requirements for drinking water. Furthermore, the SERS intensity was linear with the log of the Hg2+ concentration between 1 pM and 100 nM, with a correlation coefficient of 0.992. There was no significant interference when other metal ions were present, which shows the excellent selectivity of the SERS sensor. Unknown Hg2+ concentrations in water can be readily determined in an accurate and reliable manner, with a relative standard deviation of ∼9.21%.

Photo-induced programmable degradation of carboxymethyl chitosan-based hydrogels.

Hydrogels are widely used in the biomedical field, due to their high similarity to native extracellular matrix (ECM). Most responsive hydrogels could only passively receive stimuli and independently change their properties. In this study, a photosensitive o-nitrobenzyl (NB) ester linker of polyethylene glycol (PEG) with maleimido (Mal) as terminal groups (PEG-NB-Mal) and a 5-methylfurfuryl (mF) grafted carboxymethyl chitosan (CMCS) derivative (CMCS-mF) were synthesized and used to prepare functional hydrogels via Diels-Alder (DA) reactions. The hydrogel exhibited programmable degradation properties after sequential exposure to UV light and acid treatments. It can maintain high integrity upon the single stimuli, the cascade acid and UV light treatments or the cascade UV light and alkaline treatments. Moreover, the hydrogel exhibited well controlled release profile of rhodamine B (RB). In summary, such CMCS-based hydrogels show great potential in biomedical applications. In addition, the usage of photo-induced cascade reaction in sequential degradation hydrogels can be extended to design other types of programmable smart materials.