Tumor cells actively produce, release, and utilize exosomes to promote tumor growth. Mechanisms through which tumor-derived exosomes subserve the tumor are under intense investigation. These exosomes are information carriers, conveying molecular and genetic messages from tumor cells to normal or other abnormal cells residing at close or distant sites. Tumor-derived exosomes are found in all body fluids. Upon contact with target cells, they alter phenotypic and functional attributes of recipients, reprogramming them into active contributors to angiogenesis, thrombosis, metastasis, and immunosuppression. Exosomes produced by tumors carry cargos that in part mimic contents of parent cells and are of potential interest as noninvasive biomarkers of cancer. Their role in inhibiting the host antitumor responses and in mediating drug resistance is important for cancer therapy. Tumor-derived exosomes may interfere with cancer immunotherapy, but they also could serve as adjuvants and antigenic components of antitumor vaccines. Their biological roles in cancer development or progression as well as cancer therapy suggest that tumor-derived exosomes are critical components of oncogenic transformation.

Tumor-Derived Exosomes and Their Role in Cancer Progression.

Dynamic DNA nanotechnology, a subfield of DNA nanotechnology, is concerned with the study and application of nucleic acid strand-displacement reactions. Strand-displacement reactions generally proceed by three-way or four-way branch migration and initially were investigated for their relevance to genetic recombination. Through the use of toeholds, which are single-stranded segments of DNA to which an invader strand can bind to initiate branch migration, the rate with which strand displacement reactions proceed can be varied by more than 6 orders of magnitude. In addition, the use of toeholds enables the construction of enzyme-free DNA reaction networks exhibiting complex dynamical behavior. A demonstration of this was provided in the year 2000, in which strand displacement reactions were employed to drive a DNA-based nanomachine (Yurke, B.; et al. Nature 2000, 406, 605–608). Since then, toehold-mediated strand displacement reactions have been used with ever increasing sophistication and the field of dynam...

Principles and Applications of Nucleic Acid Strand Displacement Reactions

Developing powerful, simple and low-cost DNA amplification techniques is of great significance to bioanalysis and biomedical research Thus far, many signal amplification strategies have been developed, such as polymerase chain reaction (PCR), rolling circle amplification (RCA), and DNA strand displacement amplification (SDA) In particular, hybridization chain reaction (HCR), a type of toehold-mediated strand displacement (TMSD) reaction, has attracted great interest because of its enzyme-free nature, isothermal conditions, simple protocols, and excellent amplification efficiency In a typical HCR, an analyte initiates the cross-opening of two DNA hairpins, yielding nicked double helices that are analogous to alternating copolymers As an efficient amplification platform, HCR has been utilized for the sensitive detection of a wide variety of analytes, including nucleic acids, proteins, small molecules, and cells In recent years, more complicated sets of monomers have been designed to develop nonlinear HCR, such as branched HCR and even dendritic systems, achieving quadratic and exponential growth mechanisms In addition, HCR has attracted enormous attention in the fields of bioimaging and biomedicine, including applications in fluorescence in situ hybridization (FISH) imaging, live cell imaging, and targeted drug delivery In this review, we introduce the fundamentals of HCR and examine the visualization and analysis techniques for HCR products in detail The most recent HCR developments in biosensing, bioimaging, and biomedicine are subsequently discussed with selected examples Finally, the review provides insight into the challenges and future perspectives of HCR

Hybridization chain reaction: a versatile molecular tool for biosensing, bioimaging, and biomedicine

This work reports a ZIF-8 (ZIF: Zeolitic Imidazolate Framework)-assisted NaYF4:Yb,Tm@ZnO upconverter for the photoelectrochemical (PEC) biosensing of carcinoembryonic antigen (CEA) under near-infrared (NIR) irradiation on a homemade 3D-printed device with DNA walker-based amplification strategy. The composite photosensitive material NaYF4:Yb,Tm@ZnO, as converter to transfer NIR import to photocurrent output, was driven from annealed NaYF4:Yb,Tm@ZIF-8. Yb3+ and Tm3+-codoped NaYF4 (NaYF4:Yb,Tm) converted NIR excitation into UV emission, matching with the absorption of ZnO for in situ excitation to generate the photocurrent. Upon target CEA introduction, the swing arm of DNA walker including the sequence of CEA aptamer carried out the sandwiched bioassembly with CEA capture aptamer on the G-rich anchorage DNA tracks-functionalized magnetic beads. Thereafter, DNA walker was triggered, and the swing arm DNA was captured by the G-rich anchorage DNA according to partly complementary pairing and Exonuclease III (Exo III) consumed anchorage DNA by a burnt-bridge mechanism to go into the next cycle. The released guanine (G) bases from DNA walker enhanced the photocurrent response on a miniature homemade 3D-printed device consisting of the detection cell, dark box, and light platform. Under optimal conditions, NaYF4:Yb,Tm@ZnO-based NIR light-driven PEC biosensor presented high sensitivity and selectivity for CEA sensing with a detection limit of 0.032 ng mL-1. Importantly, our strategy provides a new horizon for the development of NIR-based PEC biosensors in the aspect of developing MOF-derived photoelectric materials, flexible design of a 3D-printed device, and effective signal amplification mode.

ZIF-8-Assisted NaYF4:Yb,Tm@ZnO Converter with Exonuclease III-Powered DNA Walker for Near-Infrared Light Responsive Biosensor

DNA is traditionally known as a central genetic biomolecule in living systems. From an alternative perspective, DNA is a versatile molecular building-block for the construction of functional materials, in particular biomaterials, due to its intrinsic biological attributes, molecular recognition capability, sequence programmability, and biocompatibility. The topologies of DNA building-blocks mainly include linear, circular, and branched types. Branched DNA recently has been extensively employed as a versatile building-block to synthesize new biomaterials, and an assortment of promising applications have been explored. In this review, we discuss the progress on DNA functional materials assembled from branched DNA. We first briefly introduce the background information on DNA molecules and sketch the development history of DNA functional materials constructed from branched DNA. In the second part, the synthetic strategies of branched DNA as building-blocks are categorized into base-pairing assembly and chemical bonding. In the third part, construction strategies for the branched DNA-based functional materials are comprehensively summarized including tile-mediated assembly, DNA origami, dynamic assembly, and hybrid assembly. In the fourth part, applications including diagnostics, protein engineering, drug and gene delivery, therapeutics, and cell engineering are demonstrated. In the end, an insight into the challenges and future perspectives is provided. We envision that branched DNA functional materials can not only enrich the DNA nanotechnology by ingenious design and synthesis but also promote the development of interdisciplinary fields in chemistry, biology, medicine, and engineering, ultimately addressing the growing demands on biological and medical-related applications in the real world.

DNA Functional Materials Assembled from Branched DNA: Design, Synthesis, and Applications.

A catalytic assembled enzyme-free three-dimensional DNA walker and its sensing application.

Preparation of functionalized magnetic graphene oxide/lignin composite nanoparticles for adsorption of heavy metal ions and reuse as electromagnetic wave absorbers

Cytokines play important roles in the immune system and have been regarded as biomarkers. While single cytokine is not specific and accurate enough to meet the strict diagnosis in practice, in this work, we constructed a multiplexed detection method for cytokines based on dual bar-code strategy and single-molecule counting. Taking interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) as model analytes, first, the magnetic nanobead was functionalized with the second antibody and primary bar-code strands, forming a magnetic nanoprobe. Then, through the specific reaction of the second antibody and the antigen that fixed by the primary antibody, sandwich-type immunocomplex was formed on the substrate. Next, the primary bar-code strands as amplification units triggered multibranched hybridization chain reaction (mHCR), producing nicked double-stranded polymers with multiple branched arms, which were served as secondary bar-code strands. Finally, the secondary bar-code strands hybridized with the multimolecule labeled fluorescence probes, generating enhanced fluorescence signals. The numbers of fluorescence dots were counted one by one for quantification with epi-fluorescence microscope. By integrating the primary and secondary bar-code-based amplification strategy and the multimolecule labeled fluorescence probes, this method displayed an excellent sensitivity with the detection limits were both 5 fM. Unlike the typical bar-code assay that the bar-code strands should be released and identified on a microarray, this method is more direct. Moreover, because of the selective immune reaction and the dual bar-code mechanism, the resulting method could detect the two targets simultaneously. Multiple analysis in human serum was also performed, suggesting that our strategy was reliable and had a great potential application in early clinical diagnosis.

Multiplexed Detection of Cytokines Based on Dual Bar-Code Strategy and Single-Molecule Counting

Zinc-based metal-organic framework nanofibers membrane ZIF-65/PAN as efficient peroxymonosulfate activator to degrade aqueous ciprofloxacin

DNA nanostructure-based drug delivery nanosystems in cancer therapy

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