Multifunctional nano-biosensor based on metal-organic framework for enhanced fluorescence imaging of intracellular miRNA-122 and synergistic chemo-photothermal therapy of tumor cells

Self-assembly of hyperbranched DNA network structure for signal amplification detection of miRNA

Catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) can achieve the high sensitivity and rapid reaction rate in detecting miRNA. However, the amplification efficiency by these methods are limited. Herein, an enzyme-free and label-free hyperbranched DNA network structure (HDNS) was designed, in which localized catalytic hairpin assembly (LCHA) and hybridization chain reaction occurred in the horizontal axis and longitudinal axis, respectively, exhibiting intensive signal dual-amplification. miRNA-122 was selected as the target on behalf of miRNA to design the HDNS sensor. The fluorescence signal change of HDNS showed good linearity for detecting miRNA-122 in the concentration range from 0.1 nM to 60 nM with a limit of detection (LOD) at 37 pM which was lower than those of the sensors based on separate CHA or HCR. Afterwards, the HDNS sensor was applied to detect miRNA-122 in serum samples with the recovery rate in the range of 97.2 %-107 %. The sensor could distinguish different kinds of miRNAs, even the family members with high sequence homology, exhibiting excellent selectivity. This method provided a novel design strategy for improving the sensitivity and selectivity of DNA sensor for miRNA detection.

Biomedical application of metal-organic frameworks (MOFs) in cancer therapy: Stimuli-responsive and biomimetic nanocomposites in targeted delivery, phototherapy and diagnosis

The nanotechnology is an interdisciplinary field that has become a hot topic in cancer therapy. Metal-organic frameworks (MOFs) are porous materials and hybrid composites consisted of organic linkers and metal cations. Despite the wide application of MOFs in other fields, the potential of MOFs for purpose of cancer therapy has been revealed by the recent studies. High surface area and porosity, significant drug loading and encapsulation efficiency are among the benefits of using MOFs in drug delivery. MOFs can deliver genes/drugs with selective targeting of tumor cells that can be achieved through functionalization with ligands. The photosensitizers and photo-responsive nanostructures including carbon dots and gold nanoparticles can be loaded in/on MOFs to cause phototherapy-mediated tumor ablation. The immunogenic cell death induction and increased infiltration of cytotoxic CD8+ and CD4+ T cells can be accelerated by MOF platforms in providing immunotherapy of tumor cells. The stimuli-responsive MOF platforms responsive to pH, redox, enzyme and ion can accelerate release of therapeutics in tumor site. Moreover, MOF nanocomposites can be modified ligands and green polymers to improve their selectivity and biocompatibility for cancer therapy. The application of MOFs for the detection of cancer-related biomarkers can participate in the early diagnosis of patients.

Recent advances in surface-mounted metal-organic framework thin film coatings for biomaterials and medical applications: a review

Coatings of metal-organic frameworks (MOFs) have potential applications in surface modification for medical implants, tissue engineering, and drug delivery systems. Therefore, developing an applicable method for surface-mounted MOF engineering to fabricate protective coating for implant tissue engineering is a crucial issue. Besides, the coating process was desgined for drug infusion and effect opposing chemical and mechanical resistance. In the present review, we discuss the techniques of MOF coatings for medical application in both in vitro and in vivo in various systems such as in situ growth of MOFs, dip coating of MOFs, spin coating of MOFs, Layer-by-layer methods, spray coating of MOFs, gas phase deposition of MOFs, electrochemical deposition of MOFs. The current study investigates the modification in the implant surface to change the properties of the alloy surface by MOF to improve properties such as reduction of the biofilm adhesion, prevention of infection, improvement of drugs and ions rate release, and corrosion resistance. MOF coatings on the surface of alloys can be considered as an opportunity or a restriction. The presence of MOF coatings in the outer layer of alloys would significantly demonstrate the biological, chemical and mechanical effects. Additionally, the impact of MOF properties and specific interactions with the surface of alloys on the anti-microbial resistance, anti-corrosion, and self-healing of MOF coatings are reported. Thus, the importance of multifunctional methods to improve the adhesion of alloy surfaces, microbial and corrosion resistance and prospects are summarized.

Dual-mode biosensor platform based on synergistic effects of dual-functional hybrid nanomaterials

Detection of biomarkers is very vital in the prevention, diagnosis and treatment of diseases. However, due to the poor accuracy and sensitivity of the constructed biosensors, we are now facing great challenges. In addressing these problems, nanohybrid-based dual mode biosensors including optical-optical, optical-electrochemical and electrochemical-electrochemical have been developed to detect various biomarkers. Integrating the merits of nanomaterials with abundant active sites, synergy and excellent physicochemical properties, many bi-functional nanohybrids have been reasonable designed and controllable preparation, which applied to the construction dual mode biosensors. Despite the significant progress, further efforts are still needed to develop dual mode biosensors and ensure their practical application by using portable digital devices. Therefore, the present review summarizes an in-depth evaluation of the bi-functional nanohybrids assisted dual mode biosensing platform of biomarkers. We are hoping this review could inspire further concepts in developing novel dual mode biosensors for possible detection application.

pH-activated DNA nanomachine for miRNA-21 imaging to accurately identify cancer cell

MicroRNA (miRNA) imaging has been employed to distinguish cancer cells from normal cells by exploiting the overexpression of miRNA in cancer. Inspired by the acidic extracellular tumor microenvironment, we designed a pH-activated DNA nanomachine to enable the specific detection of cancer cells using miRNA imaging. The DNA nanomachine was engineered by assembling two hairpins (Y1 and Y2) onto the surface of a ZIF-8 metal-organic framework (MOF), which decomposed under acidic conditions to release the adsorbed DNA hairpin molecules in situ. The released hairpins were captured by the target miRNA-21 and underwent catalytic hairpin assembly amplification between Y1 and Y2. The detection limit for miRNA assays using the DNA nanomachine was determined to be 27 pM, which is low enough for sensitive detection in living cells. Living cell imaging of miRNA-21 further corroborated the application of the DNA nanomachine in the identification of cancer cell.

Programming a DNA tetrahedral nanomachine as an integrative tool for intracellular microRNA biosensing and stimulus-unlocked target regulation

The synchronous detection and regulation of microRNAs (miRNAs) are essential for the early tumor diagnosis and treatment but remains a challenge. An integrative DNA tetrahedral nanomachine was self-assembled for sensitive detection and negative feedback regulation of intracellular miRNAs. This nanomachine comprised a DNA tetrahedron nanostructure as the framework, and a miRNA inhibitor-controlled allosteric DNAzyme as the core. The DNA tetrahedron brought the DNAzyme and the substrate in spatial proximity and facilitated the cellular uptake of DNAzyme. In allosteric regulation of DNAzyme, the locked tetrahedral DNAzyme (L-tetra-D) and active tetrahedral DNAzyme (A-Tetra-D) were controlled by miRNA inhibitor. The combination of miRNA inhibitor and target could trigger the conformational change from L-tetra-D to A-Tetra-D. A-Tetra-D cleaved the substrate and released fluorescence for intracellular miRNA biosensing. The DNA tetrahedral nanomachine showed excellent sensitivity (with detection limit down to 0.77 pM), specificity (with one-base mismatch discrimination), biocompatibility and stability. Simultaneously, miRNA stimulus-unlocked inhibitor introduced by our nanomachine exhibited the synchronous regulation of target cells, of which regulatory performance has been verified by the upregulated levels of downstream genes/proteins and the increased cellular apoptosis. Our study demonstrated that the DNA tetrahedral nanomachine is a promising biosense-and-treat tool for the synchronous detection and regulation of intracellular miRNA, and is expected to be applied in the early diagnosis and tailored management of cancers.

pH-Responsive Polymer Nanomaterials for Tumor Therapy

The complexity of the tumor microenvironment presents significant challenges to cancer therapy, while providing opportunities for targeted drug delivery. Using characteristic signals of the tumor microenvironment, various stimuli-responsive drug delivery systems can be constructed for targeted drug delivery to tumor sites. Among these, the pH is frequently utilized, owing to the pH of the tumor microenvironment being lower than that of blood and healthy tissues. pH-responsive polymer carriers can improve the efficiency of drug delivery in vivo, allow targeted drug delivery, and reduce adverse drug reactions, enabling multifunctional and personalized treatment. pH-responsive polymers have gained increasing interest due to their advantageous properties and potential for applicability in tumor therapy. In this review, recent advances in, and common applications of, pH-responsive polymer nanomaterials for drug delivery in cancer therapy are summarized, with a focus on the different types of pH-responsive polymers. Moreover, the challenges and future applications in this field are prospected.