Fishing unfunctionalized SERS tags with DNA hydrogel network generated by ligation-rolling circle amplification for simple and ultrasensitive detection of kanamycin

Advances in Functional Nucleic Acid SERS Sensing Strategies

Functional nucleic acids constitute a distinct category of nucleic acids that diverge from conventional nucleic acid amplification methodologies. They are capable of forming intricate hybrid structures through Hoogsteen and reverse Hoogsteen hydrogen bonding interactions between double-stranded and single-stranded DNA, thereby broadening the spectrum of DNA interactions. In recent years, functional DNA/RNA-based surface-enhanced Raman spectroscopy (SERS) has emerged as a potent platform capable of ultrasensitive and multiplexed detection of a variety of analytes of interest. This review aims to elucidate the operational principles of several functional nucleic acids in SERS detection, including DNAzymes, G-quadruplexes, aptamers, CRISPR, origami etc., alongside the design methodologies and practical applications of functional DNA/RNA-based SERS sensing. Initially, an overview is summarized encompassing the structural attributes and SERS sensing mechanisms inherent to diverse functional DNA/RNA. Following this, various innovative strategies for constructing functional nucleic acid-based SERS sensors are illustrated in detail, aimed at improving the present detection capabilities. A comprehensive summing up is then conducted on the applications of these sensors in crucial fields, such as disease diagnosis, environmental monitoring, and food safety detection, with a particular focus on SERS sensitivity, specificity, and analytical versatility. Finally, conclusive remarks are offered along with an exploration of the existing challenges and prospective avenues for future research in this developed field.

Multifunctional DNA-Metal Nanohybrids Derived From DNA-MgPPi Microhybrids by Rolling Circle Amplification

Rolling circle amplification (RCA)-derived ultra-long DNA is highly attractive and versatile because of its diverse functionalities conferred by repeated DNA nanostructures. However, magnesium pyrophosphate (MgPPi) crystals, as byproducts of RCA, electrostatically interact with the DNA to form DNA microhybrids and hamper its broad bioapplications, as its large size is unfavorable for cellular uptake and decreases the density of functional DNA nanostructures. In this study, finely tuned synthesis strategies are developed to condense the microhybrids and replace non-functional MgPPi crystals with various functional metal nanostructures by reducing metal ions. By applying this condensation and reduction process to DNA templated by microhybrids, the particle size of organic-inorganic DNA-MgPPi microhybrids is gradually reconfigured into DNA-Au nanohybrids (≈15 fold difference). The effects of the ion concentration and metal ion type on the reduction process are systematically explored through morphological, structural, and compositional analyses. Upon formation of the nanohybrids, the preservation of Au nanostructures and polymerized DNA nanostructure-driven functions are evaluated. The nanohybrids demonstrated not only metal nanoparticle-based near-infrared absorbance but also DNA aptamer-mediated targeted intracellular delivery, indicating successful hybridization of functional organic-inorganic molecules. This synthesis method for RCA-originated ultra-long DNA-metal nanohybrids shows potential for a variety of biological applications.

Novel Multimode Assay Based on Asymmetrically Competitive CRISPR and Raman Barcode Spectra for Multiple Hepatocellular Carcinoma Biomarkers Detection

Commercial pregnancy test strips (PTS) possess the advantages of lower price, higher stability, and better repeatability and have been popularized to integrate with novel sensing strategies to detect other disease biomarkers, which accelerates the commercialization process of those novel sensing strategies. However, the current integration of novel sensing strategies into commercial PTS still faced the problems of insufficient quantification, low sensitivity, and lack of multiple detection capabilities. Hence, we proposed the concept of "visual classification recognition, spectral signal subdivision" for multiple hepatocellular carcinoma biomarkers (miRNA122 and miRNA233) detection with dual signals based on asymmetric competitive CRISPR (acCRISPR) and surface-enhanced Raman spectroscopy coupling with PTS, named the acCRISPR-PTS-SERS assay. In this assay, acCRISPR was used as a nonamplified cascaded signal amplification method to improve the sensitivity of detection. Two AuNPs-based core-shell Raman tags, each corresponding to different miRNA biomarkers, were used to achieve both visual recognition and spectral segmentation to enhance the quantification of PTS detection and the capability for multiple detection. Under the optimal conditions, the LOD for miRNA122 and miRNA223 were 10.36 and 4.65 fM, respectively. The sensitivity was enhanced by nearly 2 orders of magnitude. In the future, simultaneous hand-held detection for fingerprint barcodes of different cancers can be achieved with the assistance of a microfluidic chip and smartphone.

Enhancing efficiency and control in DNA hydrogel synthesis: A dual rolling circle amplification approach and parameter optimization study

DNA hydrogels are a focus of current research in the realm of cutting-edge functional biomaterials. Rolling circle amplification (RCA) technology has surfaced as a flexible approach for producing functional DNA hydrogels in a one-pot manner, owing to its effectiveness and ease of use. This study introduces a simple dual RCA approach for producing DNA hydrogels. Our research delves into the impacts of different reaction parameters, such as reaction buffer, ethylenediaminetetraacetic acid (EDTA) concentration, base pair types and ratios, circular DNA template concentration, and RCA temperature, on the yield, morphology, and rheological characteristics of the resulting DNA hydrogels. Our findings demonstrate that DNA hydrogels prepared with TE buffer containing 1 mM EDTA, higher concentrations of circular DNA templates, and an RCA reaction temperature of 30 °C exhibited improved morphological characteristics and favorable mechanical properties. Furthermore, while G-C base pairs significantly enhance the mechanical properties of the hydrogel at lower concentrations, their excessive presence may negatively impact both the formation and mechanical integrity of the hydrogel. The findings from this study are crucial for boosting the efficiency and cost-effectiveness of DNA hydrogel synthesis, enhancing their quality, and broadening their range of applications.

An all-in-one enzyme-free fluorescent aptasensor integrating localized catalyzed hairpin assembly for sensing antibiotics in food with improved detection efficiency

Enzyme-free signal amplification fluorescent aptasensors depending on multi-component freely diffusing probes have become indispensable tools for antibiotic detection in food, but they suffer from low detection efficiency and tedious operation steps. Herein, an all-in-one enzyme-free fluorescent aptasensor integrating localized catalyzed hairpin assembly (L-CHA) was designed for antibiotic detection with improved detection efficiency. In the designed aptasensor, a double-stranded DNA reactant containing an antibiotic aptamer and a primer as well as two paired hairpin DNA reactants were immobilized on one spatial-confinement DNA scaffold (that is a DNA tetrahedron). Upon addition of the target antibiotic kanamycin, the activated primer initiated L-CHA, generating an amplified fluorescence signal. Compared with previously reported enzyme-free signal amplification fluorescent aptasensors, the designed aptasensor integrated the functions of target recognition, signal transduction, and L-CHA signal amplification into a single probe. In this all-in-one design, the reactants in this aptasensor were confined to a compact space for a higher local concentration, which improved detection efficiency. In particular, this aptasensor achieved sensitive detection of kanamycin within 60 min with a low detection limit of 0.019 ng mL-1. Additionally, the designed aptasensor depended on a single probe rather than multi-component probes, leading to simplified operation steps. Furthermore, this aptasensor was employed for detecting kanamycin in spiked milk samples with recoveries of 96.00% to 108.60%, indicating an acceptable accuracy. Therefore, this L-CHA-based all-in-one enzyme-free fluorescent aptasensor offers a prospective tool for antibiotic detection in the field of food safety.

CRISPR-Responsive RCA-Based DNA Hydrogel Biosensing Platform with Customizable Signal Output for Rapid and Sensitive Nucleic Acid Detection

Current nucleic acid-responsive DNA hydrogels face significant challenges, such as the requirement for high target concentrations, frequent redesigns, and increased costs, which limit their practical applications in biosensing. To address these issues, we developed a novel biosensing platform integrating a CRISPR/Cas12a system into an RCA-based DNA hydrogel. The hydrogel used in the platform could preencapsulate diverse signal molecules comprising GelRed, methylene blue, and gold nanoparticles, which were released upon Cas12a-mediated cleavage. This design enabled customizable signal output, including fluorescence, electrochemistry, and colorimetry, thereby ensuring the platform's adaptability to various detection scenarios. Our platform was highly specific for methicillin-resistant Staphylococcus aureus, with a mecA gene detection limit of 10 copies/μL, and provided fast and accurate results within 2 h for clinical samples. Hence, based on these advantages, the proposed biosensing platform exhibits promising application prospects in the field of nucleic acid detection.

Label/immobilization-free Cas12a-based electrochemiluminescence biosensor for sensitive DNA detection

Electrochemiluminescence (ECL) is one of the most sensitive techniques in the field of diagnostics. However, they typically require luminescent labeling and electrode surface biological modification, which is a time-consuming and laborious process involving multiple steps and may also lead to low reaction efficiency. Fabricating label/modification-free biosensors has become one of the most attractive parts for simplifying the ECL assays. In this work, the ECL luminophores carbon dots (CDs) were encapsulated in DNA hydrogel in situ by a simple rolling circle amplification (RCA) reaction. Upon binding of the target DNA, active Cas12a induces a collateral cleavage of the hydrogel's ssDNA backbone, resulting in a programmable degradation of the hydrogel and the release of CDs. By directly measuring the released CDs ECL, a simple and rapid label/modification-free detection of the target HPV-16 was realized. It is noted that this method allowed for 0.63 pM HPV-16 DNA detection without any amplification step, and it could take only ∼60 min for a fast test of a human serum sample. These results showed that our label/modification-free ECL biosensor has great potential for use in simple, rapid, and sensitive point-of-care (POC) detection.

Recent advances in the applications of DNA frameworks in liquid biopsy: A review

Cancer is one of the serious threats to public life and health. Early diagnosis, real-time monitoring, and individualized treatment are the keys to improve the survival rate and prolong the survival time of cancer patients. Liquid biopsy is a potential technique for cancer early diagnosis due to its non-invasive and continuous monitoring properties. However, most current liquid biopsy techniques lack the ability to detect cancers at the early stage. Therefore, effective detection of a variety of cancers is expected through the combination of various techniques. Recently, DNA frameworks with tailorable functionality and precise addressability have attracted wide spread attention in biomedical applications, especially in detecting cancer biomarkers such as circulating tumor cells (CTCs), exosomes and circulating tumor nucleic acid (ctNA). Encouragingly, DNA frameworks perform outstanding in detecting these cancer markers, but also face some challenges and opportunities. In this review, we first briefly introduced the development of DNA frameworks and its typical structural characteristics and advantages. Then, we mainly focus on the recent progress of DNA frameworks in detecting commonly used cancer markers in liquid-biopsy. We summarize the advantages and applications of DNA frameworks for detecting CTCs, exosomes and ctNA. Furthermore, we provide an outlook on the possible opportunities and challenges for exploiting the structural advantages of DNA frameworks in the field of cancer diagnosis. Finally, we envision the marriage of DNA frameworks with other emerging materials and technologies to develop the next generation of disease diagnostic biosensors.

Hydrogel-integrated sensors for food safety and quality monitoring: Fabrication strategies and emerging applications

Food safety is a global issue in public hygiene. The accurate, sensitive, and on-site detection of various food contaminants performs significant implications. However, traditional methods suffer from the time-consuming and professional operation, restricting their on-site application. Hydrogels with the merits of highly porous structure, high biocompatibility, good shape-adaptability, and stimuli-responsiveness offer a promising biomaterial to design sensors for ensuring food safety. This review describes the emerging applications of hydrogel-based sensors in food safety inspection in recent years. In particular, this study elaborates on their fabrication strategies and unique sensing mechanisms depending on whether the hydrogel is stimuli-responsive or not. Stimuli-responsive hydrogels can be integrated with various functional ligands for sensitive and convenient detection via signal amplification and transduction; while non-stimuli-responsive hydrogels are mainly used as solid-state encapsulating carriers for signal probe, nanomaterial, or cell and as conductive media. In addition, their existing challenges, future perspectives, and application prospects are discussed. These practices greatly enrich the application scenarios and improve the detection performance of hydrogel-based sensors in food safety detection.

SERS detection of apramycin and kanamycin through sliver nanoparticles modified with β-cyclodextrin and α-iron oxide

Using sliver nanoparticles modified with β-cyclodextrin and α-iron oxide (β-CD/α-Fe2O3@AgNPs) as surface-enhanced Raman spectroscopy (SERS) substrate, two sensitive methods for detecting apramycin and kanamycin were established. The synthesized β-CD/α-Fe2O3@AgNPs were characterized through ultraviolet visible (UV-vis) spectroscopy, transmission electron microscope (TEM), X-ray diffraction (XRD) and thermogravimetric analyses (TGA). The interactions of the two drugs and substrate were researched by UV-vis absorption and fourier transform infrared (FT-IR). The linear relationship between apramycin/kanamycin and SERS intensity was observed. The limits of detection (LODs) (S/N = 3) were 3.42 and 0.31 nmol/L. The two SERS methods were effectively applied to detect apramycin and kanamycin in beef samples and commercial injection. The recoveries were 96.84 - 102.20% with relative standard deviations (RSD) of 0.6---4.0% for apramycin and 95.67 - 103.18% with RSD of 1.4 - 2.5% for kanamycin, respectively.

Colloidal SERS measurement of enrofloxacin with petaloid nanostructure clusters formed by terminal deoxynucleotidyl transferase catalyzed cytosine-constituted ssDNA

We developed petal-like plasmonic nanoparticle (PLNP) clusters-based colloidal SERS method for enrofloxacin (EnFX) detection. PLNPs were synthesized by the regulation of single-stranded DNA composed of homo-cytosine deoxynucleotides (hC) catalyzed by terminal deoxynucleotidyl transferase. SERS hot spots were created via the agglomeration process of PLNPs by adding an inorganic salt potassium iodide solution, in which EnFX molecules were attached to the negatively charged PLNPs surface by electrostatic interactions. This approach enabled direct in situ detection of antibiotic residues, achieving a limit of detection (LOD) of 1.15 μg/kg for EnFX. The spiked recoveries of the SERS method were approximately 92.7% to 107.2% and the RSDs ranged from 1.05% to 7.8%, indicating that the method can be applied to actual sample detection. This colloidal SERS measurement platform would be very promising in various applications, especially in real-time and on-site food safety screening owing to its rapidness, simplicity, and sensitivity.

Recent Studies and Applications of Hydrogel-Based Biosensors in Food Safety

Food safety has increasingly become a human health issue that concerns all countries in the world. Some substances in food that can pose a significant threat to human health include, but are not limited to, pesticides, biotoxins, antibiotics, pathogenic bacteria, food quality indicators, heavy metals, and illegal additives. The traditional methods of food contaminant detection have practical limitations or analytical defects, restricting their on-site application. Hydrogels with the merits of a large surface area, highly porous structure, good shape-adaptability, excellent biocompatibility, and mechanical stability have been widely studied in the field of food safety sensing. The classification, response mechanism, and recent application of hydrogel-based biosensors in food safety are reviewed in this paper. Furthermore, the challenges and future trends of hydrogel biosensors are also discussed.

Organic Electronics in Biosensing: A Promising Frontier for Medical and Environmental Applications

The promising field of organic electronics has ushered in a new era of biosensing technology, thus offering a promising frontier for applications in both medical diagnostics and environmental monitoring. This review paper provides a comprehensive overview of organic electronics' remarkable progress and potential in biosensing applications. It explores the multifaceted aspects of organic materials and devices, thereby highlighting their unique advantages, such as flexibility, biocompatibility, and low-cost fabrication. The paper delves into the diverse range of biosensors enabled by organic electronics, including electrochemical, optical, piezoelectric, and thermal sensors, thus showcasing their versatility in detecting biomolecules, pathogens, and environmental pollutants. Furthermore, integrating organic biosensors into wearable devices and the Internet of Things (IoT) ecosystem is discussed, wherein they offer real-time, remote, and personalized monitoring solutions. The review also addresses the current challenges and future prospects of organic biosensing, thus emphasizing the potential for breakthroughs in personalized medicine, environmental sustainability, and the advancement of human health and well-being.

Construction of Liquid Crystal-Based Sensors Using Enzyme-Linked Dual-Functional Nucleic Acid on Magnetic Beads

The development of liquid crystal (LC)-based sensors with superior performances such as high portability, excellent stability, great convenience, and remarkable sensitivity is highly demanded. This work proposes a new strategy for constructing the LC-based sensor using enzyme-linked dual-functional nucleic acid (d-FNA) on magnetic beads (MBs). The detection of kanamycin (KA) is demonstrated as a model. Acetylcholinesterase (AChE) is assembled onto the KA aptamer-modified MBs with a d-FNA strand that consists of an AChE aptamer and the complementary sequence of a KA aptamer. As the specific recognition of KA by its aptamer triggers the release of AChE from the MBs, the myristoylcholine (Myr) solution after incubation with the MBs causes the black image of the LCs due to the formation of the Myr monolayer at the aqueous/LC interface. Otherwise, in the absence of KA, AChE is still decorated on the MBs and causes the hydrolysis of Myr. Therefore, a bright image of LCs is obtained. The detection of KA is successfully achieved with a lower detection limit of 48.1 pg/mL. In addition, a thin polydimethylsiloxane (PDMS) layer-coated glass and a portable optical device are used to improve the stability and portability of the LC-based sensor to advance potential commercial applications. Furthermore, the detection of KA in milk with a portable device is demonstrated, showing the potential of the proposed enzyme-linked LC-based sensor.

Investigation of the Impact of Hydrogen Bonding Degree in Long Single-Stranded DNA (ssDNA) Generated with Dual Rolling Circle Amplification (RCA) on the Preparation and Performance of DNA Hydrogels

DNA hydrogels have gained significant attention in recent years as one of the most promising functional polymer materials. To broaden their applications, it is critical to develop efficient methods for the preparation of bulk-scale DNA hydrogels with adjustable mechanical properties. Herein, we introduce a straightforward and efficient molecular design approach to producing physically pure DNA hydrogel and controlling its mechanical properties by adjusting the degree of hydrogen bonding in ultralong single-stranded DNA (ssDNA) precursors, which were generated using a dual rolling circle amplification (RCA)-based strategy. The effect of hydrogen bonding degree on the performance of DNA hydrogels was thoroughly investigated by analyzing the preparation process, morphology, rheology, microstructure, and entrapment efficiency of the hydrogels for Au nanoparticles (AuNPs)-BSA. Our results demonstrate that DNA hydrogels can be formed at 25 °C with simple vortex mixing in less than 10 s. The experimental results also indicate that a higher degree of hydrogen bonding in the precursor DNA resulted in stronger internal interaction forces, a more complex internal network of the hydrogel, a denser hydrogel, improved mechanical properties, and enhanced entrapment efficiency. This study intuitively demonstrates the effect of hydrogen bonding on the preparation and properties of DNA hydrogels. The method and results presented in this study are of great significance for improving the synthesis efficiency and economy of DNA hydrogels, enhancing and adjusting the overall quality and performance of the hydrogel, and expanding the application field of DNA hydrogels.

Stimuli-responsive SERS biosensor for ultrasensitive tetracycline sensing using EDTA-driven PEI@CaCO3 microcapsule and CS@FeMMs

In this work, a stimuli-responsive SERS biosensor was fabricated for tetracycline (TTC) by "signal-on" strategy using (EDTA)-driven polyethyleneimine grafted calcium carbonate (PEI@CaCO₃) microcapsule and chitosan-Fe magnetic microbeads (CS@FeMMs). Initially, aptamer conjugated magnetic-bead CS@FeMMs@Apt with superparamagnetism and excellent biocompatibility was employed as capture probe, which facilitated the rapid and easy magnetic separation. Subsequently, the PEI cross-linked layer and aptamer network layer were constructed onto the outer layer of CaCO₃@4-ATP microcapsule to form sensing probes (PEI@CaCO₃@4-ATP@Apt) via the layer-by-layer assembly method. In the presence of TTC, a sandwich SERS-assay was exploited by aptamer recognition induced target-bridged strategy. When the solution of EDTA was added, the core layer of CaCO₃ would be dissolved quickly, destroying the microcapsule to release 4-ATP. The released 4-ATP could be quantitatively monitored by dripping the supernatant onto the AuNTs@PDMS SERS platform, resulting in a strong Raman "signal-on". Under the optimal conditions, a good linear relationship was established with a correlation coefficient (R²) of 0.9938 and a LOD of 0.03 ng/mL. Additionally, the application capacity of the biosensor to detect TTC was also affirmed in food matrixes, and the results were consistent with the standard ELISA method (P > 0.05). Hence, this SERS biosensor affords extensive application prospects for TTC detection with multiple merits such as high sensitivity, environment friendliness, and high stability.

Stimulus-Responsive DNA Hydrogel Biosensors for Food Safety Detection

Food safety has always been a major global challenge to human health and the effective detection of harmful substances in food can reduce the risk to human health. However, the food industry has been plagued by a lack of effective and sensitive safety monitoring methods due to the tension between the cost and effectiveness of monitoring. DNA-based hydrogels combine the advantages of biocompatibility, programmability, the molecular recognition of DNA molecules, and the hydrophilicity of hydrogels, making them a hotspot in the research field of new nanomaterials. The stimulus response property greatly broadens the function and application range of DNA hydrogel. In recent years, DNA hydrogels based on stimulus-responsive mechanisms have been widely applied in the field of biosensing for the detection of a variety of target substances, including various food contaminants. In this review, we describe the recent advances in the preparation of stimuli-responsive DNA hydrogels, highlighting the progress of its application in food safety detection. Finally, we also discuss the challenges and future application of stimulus-responsive DNA hydrogels.

The self-powered electrochemical biosensing platform with multi-amplification strategy for ultrasensitive detection of microRNA-155

A self-powered biosensor (SPB) was constructed for the ultra-sensitive detection of microRNA-155 (miR-155) by combining a capacitor/enzymatic biofuel cell (EBFC), a strategy of rolling circle amplification (RCA) and a digital multimeter (DMM). The experimental results show that the sensitivity of the assembled EBFC-SPB can reach 15.85 μA/pM with the action of matching capacitor, which is 513% of that without capacitor (3.09 μA/pM). This achieves the first signal amplification. Furthermore, when the target miR-155 triggers RCA, electrons are continuous generated and flow to the biocathode through the external circuit to catalyze the reduction of oxygen and release [Ru(NH₃)₆]³⁺ electron acceptor. This achieves the second signal amplification. Finally, DMM is used to convert the signal into instantaneous current and amplify it for real-time reading. This achieves the third signal amplification. Therefore, the limit of detection (LOD) of the developed biosensor is as low as 0.17 fM (S/N = 3), and the linear range is between 0.5 fM and 10,000 fM, indicating that the EBFC-SPB has a broad application prospect for cancer marker of miR-155 with ultrasensitive detection.

Allosteric aptasensor-initiated target cycling and transcription amplification of light-up RNA aptamer for sensitive detection of protein

The early detection of biomarker proteins in clinical samples is of great significance for the diagnosis of diseases. However, it is still a challenge to detect low-concentration protein. Herein, a label-free aptamer-based amplification assay, termed the ATC-TA system, that allows fluorescence detection of very low numbers of protein without time-consuming washing steps and pre-treatment was developed. The target induces a conformational change in the allosteric aptasensor, triggers the target cycling and transcription amplification, and ultimately converts the input of the target protein into the output of the light-up aptamer (R-Pepper). It exhibits ultrahigh sensitivity with a detection limit of 5.62 fM at 37 ℃ and the accuracy is comparable to conventional ELISA. ATC-TA has potential application for the detection of endogenous PDGF-BB in serum samples to distinguish tumor mice from healthy mice at an early stage. It also successfully detects exogenous SARS-CoV-2 spike proteins in human serum. Therefore, this high-sensitive, universality, easy-to-operate and cost-effective biosensing platform holds great clinical application potential in early clinical diagnosis.

Target-mediated competitive hybridization of hairpin probes for kanamycin detection based on exonuclease III cleavage and DNAzyme catalysis

Based on aptamer recognition and target-mediated competitive hybridization of hairpin probes, we developed a fluorescence sensor for kanamycin (KAN) detection. The aptamer and KAN binding will open hairpin H1 to release the trigger DNA fragment, which can initiate the competitive hybridization between hairpins H2 and H3. Then, exonuclease III (Exo III) can cleave H2 and H3 to produce numerous DNA3 and DNA4. Through the synergetic hybridization among DNA1, DNA2, DNA3, and DNA4, an active Mg²⁺-DNAzyme can be formed. The cleavage reaction toward FAM-BHQ-modified DNA2 will produce a high fluorescence signal for KAN assay. Through Exo III-guided cleavage and Mg²⁺-DNAzyme-based catalysis, the sensor exhibits high sensitivity, with a detection limit of 3.1 fM. This method is robust and has been applied to the detection of KAN in milk and water samples with good accuracy and reliability. Our developed fluorescence sensor exhibits the advantages of simple operation, high sensitivity, and good robustness, which are beneficial for KAN detection in food samples.

Injectable DNA Hydrogel-Based Local Drug Delivery and Immunotherapy

Regulated drug delivery is an important direction in the field of medicine and healthcare research. In recent years, injectable hydrogels with good biocompatibility and biodegradability have attracted extensive attention due to their promising application in controlled drug release. Among them, DNA hydrogel has shown great potentials in local drug delivery and immunotherapy. DNA hydrogel is a three-dimensional network formed by cross-linking of hydrophilic DNA strands with extremely good biocompatibility. Benefiting from the special properties of DNA, including editable sequence and specificity of hybridization reactions, the mechanical properties and functions of DNA hydrogels can be precisely designed according to specific applications. In addition, other functional materials, including peptides, proteins and synthetic organic polymers can be easily integrated with DNA hydrogels, thereby enriching the functions of the hydrogels. In this review, we first summarize the types and synthesis methods of DNA hydrogels, and then review the recent research progress of injectable DNA hydrogels in local drug delivery, especially in immunotherapy. Finally, we discuss the challenges facing DNA hydrogels and future development directions.