Vertasile ferritin nanocages: Applications in detection and bioimaging

Food safety and human health remain significant concerns in the food industry. Detecting food contaminants and diagnosing diseases are critical aspects. Ferritin, an iron storage protein widely found in nature, offers unique advantages. Its hollow protein nanocage structure, distinct interfaces, hydrophobic or hydrophilic channels, and B-C loop regions recognized by transferrin receptor 1 make ferritin versatile for detecting heavy metals, free radicals, and bioimaging both in vitro and in vivo. This review summarizes ferritin's general characteristics, its specific properties as biosensors, and its applications in food safety and in vivo imaging. It emphasizes not only ferritin's role in detecting heavy metals like mercury and chemical hazards but also its potential in early diagnosing chronic diseases such as tumors, macrophages, and kidney diseases. Further research into ferritin promises advancements in enhancing food safety and improving human health diagnostics.

Aptamer functionalized DNA hydrogels: Design, applications and kinetics

DNA hydrogels have received considerable attention in various promising applications due to their excellent biocompatibility, controlled biodegradability, adjustable mechanical properties, stability against proteases, self-healing ability, and stimuli responsiveness. To obtain the specific molecular recognition capability, aptamers and many other functional motifs are utilized. Aptamers are short single-stranded DNA or RNA selected through SELEX to bind with specific target with high affinity and specificity. With advantages of broad range of targets, good stability, easy modification, and low cost, aptamer functionalized DNA hydrogels become popular in a wide range of promising applications. In this review, the recent progress on aptamer functionalized DNA hydrogels including general design principles, applications and kinetics has been summarized. Finally, the current challenges and prospects are discussed.

Apoferritin nanocages for targeted delivery of idarubicin against breast cancer cells

In recent years, nanotechnology has attracted attention for its capability to diagnose and remedy diverse tumors successfully.  Protein nanocarriers as a platform of targeted drug delivery can be used to reduce toxicity and improve the effect of anticancer drugs. Idarubicin (IDR) is a chemotherapy drug that is classified as an anthracycline antitumor. In this study, IDR was encapsulated within horse spleen apoferritin (HsAFr) nanocarriers. Encapsulation was obtained through disassembling apoferritin into subunits at pH 2 and subsequently reassembling it at pH 7.4 in the presence of IDR. Transmission electron microscopy, UV-vis, and fluorescence spectroscopy techniques showed that drug molecules are loaded within apoferritin. Intrinsic fluorescence information exhibited that the encapsulation does not have any effects on the tertiary structure of the protein. Drug loading and entrapment efficiency were found to be 7.15% and 84.75%, respectively. Comparison of anticancer activities in HsAFr-IDR and free drug IDR was made via the MTT viability technique in a human breast cancer cell line (MCF-7).

Colorimetric nanoplatform for visual determination of cancer cells via target-catalyzed hairpin assembly actuated aggregation of gold nanoparticles

According to aptamer-mediated hairpin DNA cascade amplifier and gold nanoparticles aggregation, an optical platform for cancer cells determination has been proposed. High-affinity chimeric aptamers were used for cancer cell detection and also as an initiator for beginning hairpin assembly to construct three-way junction (3WJ) nanostructures. These three hairpins were modified at 3' ends with biotin. In the presence of target cell, chimeric aptamer binds to its ligand on cell surface and initiates 3WJ nanostructures formation. These 3WJ nanostructures interact with streptavidin-modified gold nanoparticles (AuNPs) via non-covalent biotin-streptavidin interactions and create a crossover lattice of nanoparticles. This event leads to AuNPs aggregation and red-shifting. The results were confirmed by gel electrophoresis and UV-visible spectrophotometry. The dynamic range of this assay is 25 to 10⁷ cells with a detection limit of 10 cells which is respectively 9 and 4 times more significant than the sensitivity of AuNP-based approaches without amplification and enzyme-mediated signal amplification. Graphical abstract.

DNA hydrogel-empowered biosensing

DNA hydrogels as special members in the DNA nanotechnology have provided crucial prerequisites to create innovative gels owing to their sufficient stability, biocompatibility, biodegradability, and tunable multifunctionality. These properties have tailored DNA hydrogels for various applications in drug delivery, tissue engineering, sensors, and cancer therapy. Recently, DNA-based materials have attracted substantial consideration for the exploration of smart hydrogels, in which their properties can change in response to chemical or physical stimuli. In other words, these gels can undergo switchable gel-to-sol or sol-to-gel transitions upon application of different triggers. Moreover, various functional motifs like i-motif structures, antisense DNAs, DNAzymes, and aptamers can be inserted into the polymer network to offer a molecular recognition capability to the complex. In this manuscript, a comprehensive discussion will be endowed with the recognition capability of different kinds of DNA hydrogels and the alternation in physicochemical behaviors upon target introducing. Finally, we offer a vision into the future landscape of DNA based hydrogels in sensing applications.

Target-triggered three-way junction in conjugation with catalytic concatemers-functionalized nanocomposites provides a highly sensitive colorimetric method for miR-21 detection

With the great advances in DNA nanotechnology, scientists have shown interest in developing dynamic nanostructures for theranostic applications, analyte sensing and cargo delivery. Here, we present a specific enzyme-free ultrasensitive platform based on a multilayer coupled signal amplification strategy to quantify miR-21 molecule. The biosensor was integrated based on three signal amplification gadgets, namely a translator-mediated catalytic hairpin assembly (CHA), a multilayer DNA concatemer on the surface of gold decorated magnetic nanoparticle (GMNP), and a DNAzyme-mediated catalytic signal amplification. MiR-21 mediates the release of a DNA translator from an immobilized duplex to engage in a CHA reaction using three hairpins, including a GMNP-conjugated hairpin 1 (H1), biotin-labeled hairpin 2 (H2) and a GMNP-conjugated hairpin 3 (H3) to form a three-way junction (3WJ). Meanwhile, a plenty of initiator strand 0 (S0) on GMNPs - each of which has been bifunctionalized with S0/H1 or S0/H3 - drive several multilayer peroxidase-mimicking DNAzyme concatemers in the presence of two accessory oligonucleotides; strand 1 (S1) and strand 2 (S2). Since a G-rich sequence was attached at the 5'-end of S1 strand, in the presence of hemin cofactor, an active G-quadruplex DNAzyme with peroxidase activity was formed. The concatemers on the surface of GMNPs can convert a colorless substrate to a green product. The biosensor can detect as low as 1 aM of miR-21 and provide an excellent capability to discriminate single-base mismatches. The required time for the formulation of the assay reagents is about three days and the reaction time for the detection of miR-21 takes place in less than four hours.