Physical stimuli-responsive DNA hydrogels: design, fabrication strategies, and biomedical applications

Physical stimuli-responsive DNA hydrogels hold immense potential for tissue engineering due to their inherent biocompatibility, tunable properties, and capacity to replicate the mechanical environment of natural tissue, making physical stimuli-responsive DNA hydrogels a promising candidate for tissue engineering. These hydrogels can be tailored to respond to specific physical triggers such as temperature, light, magnetic fields, ultrasound, mechanical force, and electrical stimuli, allowing precise control over their behavior. By mimicking the extracellular matrix (ECM), DNA hydrogels provide structural support, biomechanical cues, and cell signaling essential for tissue regeneration. This article explores various physical stimuli and their incorporation into DNA hydrogels, including DNA self-assembly and hybrid DNA hydrogel methods. The aim is to demonstrate how DNA hydrogels, in conjunction with other biomolecules and the ECM environment, generate dynamic scaffolds that respond to physical stimuli to facilitate tissue regeneration. We investigate the most recent developments in cancer therapies, including injectable DNA hydrogel for bone regeneration, personalized scaffolds, and dynamic culture models for drug discovery. The study concludes by delineating the remaining obstacles and potential future orientations in the optimization of DNA hydrogel design for the regeneration and reconstruction of tissue. It also addresses strategies for surmounting current challenges and incorporating more sophisticated technologies, thereby facilitating the clinical translation of these innovative hydrogels.

Application of smart-responsive hydrogels in nucleic acid and nucleic acid-based target sensing: A review

In recent years, nucleic acid-related sensing and detection have become essential in clinical diagnostics, treatment and genotyping, especially in connection with the Human Genome Project and the COVID-19 pandemic. Many traditional nucleic acid-related sensing strategies have been employed in analytical chemistry, including fluorescence, colorimetric and chemiluminescence methods. However, their key limitation is the lack of understanding of the interaction during analysis, particularly at the 3D matrix level close to biological tissue. To address this issue, smart-responsive hydrogels are increasingly used in biosensing due to their hydrophilic and biocompatible properties. By combining smart-responsive hydrogels with traditional nucleic acid-related sensing, biological microenvironments can be mimicked, and targets can be easily accessed and diffused, making them ideal for nucleic acid sensing. This review focuses on utilizing smart-responsive hydrogels for nucleic acid-related sensing and detection, including nucleic acid detection, other nucleic acid-based analyte detection and nucleic acid-related sensing platforms applying nucleic acid as sensing tools in hydrogels. Additionally, the analytical mechanisms of smart-responsive hydrogels with the combination of various detection platforms such as optical and electrochemical techniques are described. The limitations of using smart-responsive hydrogels in nucleic acid-related sensing and proposed possible solutions are also discussed. Lastly, the future challenge of smart-responsive hydrogels in nucleic acid-related sensing is explored. Smart-responsive hydrogels can be used as biomimetic materials to simulate the extracellular matrix, achieve biosensing, and exhibit great potential in nucleic acid-related sensing. They serve as a valuable complement to traditional detection and analytical methods.

Preparation Strategies, Functional Regulation, and Applications of Multifunctional Nanomaterials-Based DNA Hydrogels

With the extensive attention of DNA hydrogels in biomedicine, biomaterial, and other research fields, more and more functional DNA hydrogels have emerged to match the various needs. Incorporating nanomaterials into the hydrogel network is an emerging strategy for functional DNA hydrogel construction. Surprisingly, nanomaterials-based DNA hydrogels can be engineered to possess favorable properties, such as dynamic mechanical properties, excellent optical properties, particular electrical properties, perfect encapsulation properties, improved magnetic properties, and enhanced antibacterial properties. Herein, the preparation strategies of nanomaterials-based DNA hydrogels are first highlighted and then different nanomaterial designs are used to demonstrate the functional regulation of DNA hydrogels to achieve specific properties. Subsequently, representative applications in biosensing, drug delivery, cell culture, and environmental protection are introduced with some selected examples. Finally, the current challenges and prospects are elaborated. The study envisions that this review will provide an insightful perspective for the further development of functional DNA hydrogels.

Application of intelligent responsive DNA self-assembling nanomaterials in drug delivery

Smart nanomaterials are nano-scaled materials that respond in a controllable and reversible way to external physical or chemical stimuli. DNA self-assembly is an effective way to construct smart nanomaterials with precise structure, diverse functions and wide applications. Among them, static structures such as DNA polyhedron, DNA nanocages and DNA hydrogels, as well as dynamic reactions such as catalytic hairpin reaction, hybridization chain reaction and rolling circle amplification, can serve as the basis for building smart nanomaterials. Due to the advantages of DNA, such as good biocompatibility, simple synthesis, rational design, and good stability, these materials have attracted increasing attention in the fields of pharmaceuticals and biology. Based on their specific response design, DNA self-assembled smart nanomaterials can deliver a variety of drugs, including small molecules, nucleic acids, proteins and other drugs; and they play important roles in enhancing cellular uptake, resisting enzymatic degradation, controlling drug release, and so on. This review focuses on different assembly methods of DNA self-assembled smart nanomaterials, therapeutic strategies based on various intelligent responses, and their applications in drug delivery. Finally, the opportunities and challenges of smart nanomaterials based on DNA self-assembly are summarized.

Rationally Tailored Mesoporous Hosts for Optimal Protein Encapsulation

Proteins play important roles in the therapeutic, medical diagnostic, and chemical catalysis industries. However, their potential is often limited by their fragile and dynamic nature outside cellular environments. The encapsulation of proteins in solid materials has been widely pursued as a route to enhance their stability and ease of handling. Nevertheless, the experimental investigation of protein interactions with rationally designed synthetic hosts still represents an area in need of improvement. In this work, we leveraged the tunability and crystallinity of metal-organic frameworks (MOFs) and developed a series of crystallographically defined protein hosts with varying chemical properties. Through systematic studies, we identified the dominating mechanisms for protein encapsulation and developed a host material with well-tailored properties to effectively encapsulate the protein ubiquitin. Specifically, in our mesoporous hosts, we found that ubiquitin encapsulation is thermodynamically favored. A more hydrophilic encapsulation environment with favorable electrostatic interactions induces enthalpically favored ubiquitin-MOF interactions, and a higher pH condition reduces the intraparticle diffusion barrier, both leading to a higher protein loading. Our findings provide a fundamental understanding of host-guest interactions between proteins and solid matrices and offer new insights to guide the design of future protein host materials to achieve optimal protein loading. The MOF modification technique used in this work also demonstrates a facile method to develop materials easily customizable for encapsulating proteins with different surface properties.

IR780-doped cobalt ferrite nanoparticles@poly(ethylene glycol) microgels as dual-enzyme immobilized micro-systems: Preparations, photothermal-responsive dual-enzyme release, and highly efficient recycling

To solve the problems of separating dual enzymes from the carriers of dual-enzyme immobilized micro-systems and greatly increase the carriers' recycling times, photothermal-responsive micro-systems of IR780-doped cobalt ferrite nanoparticles@poly(ethylene glycol) microgels (CFNPs-IR780@MGs) are prepared. A novel two-step recycling strategy is proposed based on the CFNPs-IR780@MGs. First, the dual enzymes and the carriers are separated from the reaction system as a whole via magnetic separation. Second, the dual enzymes and the carriers are separated through photothermal-responsive dual-enzyme release so that the carriers can be reused. Results show that CFNPs-IR780@MGs is 281.4 ± 9.6 nm with a shell of 58.2 nm, and the low critical solution temperature is 42 °C, and the photothermal conversion efficiency increases from 14.04% to 58.41% by doping 1.6% of IR780 into the CFNPs-IR780 clusters. The dual-enzyme immobilized micro-systems and the carriers are recycled 12 and 72 times, respectively, and the enzyme activity remains above 70%. The micro-systems can realize whole recycling of the dual enzymes and carriers and further recycling of the carriers, thus providing a simple and convenient recycling method for dual-enzyme immobilized micro-systems. The findings reveal the micro-systems' important application potential in biological detection and industrial production.

Carbon Dot-Doped Hydrogel Sensor Array for Multiplexed Colorimetric Detection of Wound Healing

Effective wound care and treatment require a quick and comprehensive assessment of healing status. Here, we develop a carbon dot-doped hydrogel sensor array in polydimethylsiloxane (PDMS) for simultaneous colorimetric detections of five wound biomarkers and/or wound condition indicators (pH, glucose, urea, uric acid, and total protein), leading to the holistic assessment of inflammation and infection. A biogenic carbon dot synthesized using an amino acid and a polymer precursor is doped in an agarose hydrogel matrix for constructing enzymatic sensors (glucose, urea, and uric acid) and dye-based sensors (pH and total protein). The encapsulated enzymes in such a matrix exhibit improved enzyme kinetics and stability compared to those in pure hydrogels. Such a matrix also provides stable colorimetric responses for all five sensors. The sensor array exhibits high accuracy (recovery rates of 91.5-113.1%) and clinically relevant detection ranges for all five wound markers. The sensor array is established for simulated wound fluids and validated with rat wound fluids from perturbed wound models. Distinct color patterns are obtained that can clearly distinguish healing vs nonhealing wounds visually and quantitatively. This hydrogel sensor array shows great potential for on-site wound sensing due to its long-term stability, lightweight, and flexibility.

Design and application of stimuli-responsive DNA hydrogels: A review

Deoxyribonucleic acid (DNA) hydrogels combine the properties of DNAs and hydrogels, and adding functionalized DNAs is key to the wide application of DNA hydrogels. In stimuli-responsive DNA hydrogels, the DNA transcends its application in genetics and bridges the gap between different fields. Specifically, the DNA acts as both an information carrier and a bridge in constructing DNA hydrogels. The programmability and biocompatibility of DNA hydrogel make it change macroscopically in response to a variety of stimuli. In order to meet the needs of different scenarios, DNA hydrogels were also designed into microcapsules, beads, membranes, microneedle patches, and other forms. In this study, the stimuli were classified into single biological and non-biological stimuli and composite stimuli. Stimuli-responsive DNA hydrogels from the past five years were summarized, including but not limited to their design and application, in particular logic gate pathways and signal amplification mechanisms. Stimuli-responsive DNA hydrogels have been applied to fields such as sensing, nanorobots, information carriers, controlled drug release, and disease treatment. Different potential applications and the developmental pro-spects of stimuli-responsive DNA hydrogels were discussed.

Hydrogels as functional components in artificial cell systems

Recent years have seen substantial efforts aimed at constructing artificial cells from various molecular components with the aim of mimicking the processes, behaviours and architectures found in biological systems. Artificial cell development ultimately aims to produce model constructs that progress our understanding of biology, as well as forming the basis for functional bio-inspired devices that can be used in fields such as therapeutic delivery, biosensing, cell therapy and bioremediation. Typically, artificial cells rely on a bilayer membrane chassis and have fluid aqueous interiors to mimic biological cells. However, a desire to more accurately replicate the gel-like properties of intracellular and extracellular biological environments has driven increasing efforts to build cell mimics based on hydrogels. This has enabled researchers to exploit some of the unique functional properties of hydrogels that have seen them deployed in fields such as tissue engineering, biomaterials and drug delivery. In this Review, we explore how hydrogels can be leveraged in the context of artificial cell development. We also discuss how hydrogels can potentially be incorporated within the next generation of artificial cells to engineer improved biological mimics and functional microsystems.

Milk Protein-Based Nanohydrogels: Current Status and Applications

Milk proteins are excellent biomaterials for the modification and formulation of food structures as they have good nutritional value; are biodegradable and biocompatible; are regarded as safe for human consumption; possess valuable physical, chemical, and biological functionalities. Hydrogels are three-dimensional, cross-linked networks of polymers capable of absorbing large amounts of water and biological fluids without dissolving and have attained great attraction from researchers due to their small size and high efficiency. Gelation is the primary technique used to synthesize milk protein nanohydrogels, whereas the denaturation, aggregation, and gelation of proteins are of specific significance toward assembling novel nanostructures such as nanohydrogels with various possible applications. These are synthesized by either chemical cross-linking achieved through covalent bonds or physical cross-linking via noncovalent bonds. Milk-protein-based gelling systems can play a variety of functions such as in food nutrition and health, food engineering and processing, and food safety. Therefore, this review highlights the method to prepare milk protein nanohydrogel and its diverse applications in the food industry.

A novel aptasensor based on DNA hydrogel for sensitive visual detection of ochratoxin A

A novel visual detection mode is proposed to improve the detection sensitivity for the determination of ochratoxin A (OTA). The mode is based on aptamer recognition and the signal amplification of rolling circle amplification (RCA) products self-assembled DNA hydrogel. Moreover, gold nanoparticles (AuNPs) were directly assembled inside the DNA hydrogel by adjusting the padlock probe sequences to achieve a stronger binding force between the DNA hydrogel and AuNPs; this avoids the need for modification of AuNPs with DNA sequences. In the presence of OTA, DNA hydrogel is formed. With higher concentrations of OTA, a larger amount of DNA hydrogel is formed. When AuNPs are added to the DNA hydrogel, AuNPs can be enclosed inside the DNA hydrogel. With more DNA hydrogel, there is less AuNPs in the supernatant. Thus, the absorbance of the supernatant is anti-correlated with the concentration of OTA. After optimization of the experimental conditions, the change in the absorbance of the supernatant was linearly correlated with the concentration of OTA, in the range 0.05 to 10 ng/mL; the limit of detection was 0.005 ng/mL. The good specificity of the developed biosensor was confirmed in the presence of other mycotoxins that are coexistent with or analogues of OTA. By comparing the developed method with the ELISA method, the accuracy and stability of this new method were also verified, with good performance obtained in real samples. Diagram of the principle of the colorimetric aptasensor for OTA detection based on rolling circle amplification product self-assembled DNA hydrogel.

A portable thermal detection method based on the target responsive hydrogel mediated self-heating of a warming pad

A simple thermal aptasensing platform was devised for the sensitive detection of organophosphate pesticides (using malathion as a model target) based on the efficient self-heating reaction of a warming pad with a switchable target responsive enzyme-encapsulated three-dimensional (3D) DNA hydrogel using a portable thermometer as a signal readout in this work. The existence of the target malathion would open the catalase-3D network and lots of catalase was released from the hydrogel, which could efficiently convert H₂O₂ to an O₂ molecule. The product O₂ is the critical condition for the self-heating of the warming pad. Thereafter, the temperature was enhanced with the increasing amount of O₂. The strategy displays outstanding specificity, reproducibility and stability. Moreover, this method can be easily extended to monitor other molecules using different aptamer sequences in practical applications.

Fabrication of magnetic dual-hydrophilic metal organic framework for highly efficient glycopeptide enrichment

Highly selective glycopeptide enrichment is important before mass spectrometry analysis because of the ultra-low abundance of glycopeptides in the peptide mixtures. Herein, a UiO-66-NH₂-based magnetic composite was prepared and used for the hydrophilic enrichment of glycopeptides. The composite was modified with phytic acid (PA) molecules by partially replacing 2-aminoterephthalic acid ligands in UiO-66-NH₂, with electrostatic interactions also promoting this modification process. Based on the hydrophilicity of both the PA molecules and the UiO-66-NH₂ skeleton, the resulting material, denoted as MUiO-66-NH₂/PA, showed excellent dual hydrophilicity towards glycopeptide enrichment. Compared with pure UiO-66-NH₂, the specific surface area and hydrophilicity of the prepared material were increased, and MUiO-66-NH₂/PA exhibited good magnetic responsiveness to facilitate a convenient enrichment procedure. HRP and IgG were used as standard proteins to evaluate the glycopeptide enrichment properties, with 21 and 34 glycopeptides enriched from their tryptic digests. Furthermore, MUiO-66-NH₂/PA showed outstanding sensitivity (1 fmol/μL) and selectivity (HRP/BSA = 1:1000), and achieved remarkable glycopeptide enrichment performance for practical human serum samples. Notably, MUiO-66-NH₂/PA showed perfect reusability and stability, achieving enrichment performance after five cycles similar to that of the first use. This material can be used for glycopeptide enrichment to obtain further glycosylation information, providing the possibility for cancer treatment.

Advances in the synthesis and application of self-assembling biomaterials

The present study scrutinized some of the crucial advancements in the synthesis and functionalisation of self-assembling biomaterials for application in biomedicine. The basic concept of self-organization was discussed along with the mechanisms and methods involved in its implementation with biomaterials. Further, several recent applications of this technology in the biological and medical domain, and the avenues for future research and development were presented. This study brought to focus the vast potential of basic and applied research involved, especially in the context of hybrids and composites, as well as the difference in pace of new developments for different types of biomolecular materials. As nanobiotechnology matures, the tools and techniques available for developing and controlling self-assembled biomaterials as well as studying their interaction with biological tissue, will grow exponentially. Presently, self-assembly remains a potent tool for the synthesis of functional biomaterials.

Smart and Functionalized Development of Nucleic Acid-Based Hydrogels: Assembly Strategies, Recent Advances, and Challenges

Nucleic acid-based hydrogels that integrate intrinsic biological properties of nucleic acids and mechanical behavior of their advanced assemblies are appealing bioanalysis and biomedical studies for the development of new-generation smart biomaterials. It is inseparable from development and incorporation of novel structural and functional units. This review highlights different functional units of nucleic acids, polymers, and novel nanomaterials in the order of structures, properties, and functions, and their assembly strategies for the fabrication of nucleic acid-based hydrogels. Also, recent advances in the design of multifunctional and stimuli-responsive nucleic acid-based hydrogels in bioanalysis and biomedical science are discussed, focusing on the applications of customized hydrogels for emerging directions, including 3D cell cultivation and 3D bioprinting. Finally, the key challenge and future perspectives are outlined.

Magnetic-responsive hydrogels: From strategic design to biomedical applications

Smart hydrogels which can respond to external stimuli have been widely focused with increasing interest. Thereinto, magnetic-responsive hydrogels that are prepared by embedding magnetic nanomaterials into hydrogel networks are more advantageous in biomedical applications due to their rapid magnetic response, precisely temporal and spatial control and non-invasively remote actuation. Upon the application of an external magnetic field, magnetic hydrogels can be actuated to perform multiple response modes such as locomotion, deformation and thermogenesis for therapeutic purposes without the limit of tissue penetration depth. This review summarizes the latest advances of magnetic-responsive hydrogels with focus on biomedical applications. The synthetic methods of magnetic hydrogels are firstly introduced. Then, the roles of different response modes of magnetic hydrogels played in different biomedical applications are emphatically discussed in detail. In the end, the current limitations and future perspectives for magnetic hydrogels are given.

Artificial Bioaugmentation of Biomacromolecules and Living Organisms for Biomedical Applications

The synergistic union of nanomaterials with biomaterials has revolutionized synthetic chemistry, enabling the creation of nanomaterial-based biohybrids with distinct properties for biomedical applications. This class of materials has drawn significant scientific interest from the perspective of functional extension via controllable coupling of synthetic and biomaterial components, resulting in enhancement of the chemical, physical, and biological properties of the obtained biohybrids. In this review, we highlight the forefront materials for the combination with biomacromolecules and living organisms and their advantageous properties as well as recent advances in the rational design and synthesis of artificial biohybrids. We further illustrate the incredible diversity of biomedical applications stemming from artificially bioaugmented characteristics of the nanomaterial-based biohybrids. Eventually, we aim to inspire scientists with the application horizons of the exciting field of synthetic augmented biohybrids.

Combination of DNA with polymers

The preparation and applications of DNA containing polymers are comprehensively reviewed, and they are in the form of DNA−polymer covalent conjugators, supramolecular assemblies and hydrogels for advanced materials with promising features.

Enhanced enzymatic activity and stability by in situ entrapment of α-Glucosidase within super porous p(HEMA) cryogels during synthesis

Here, poly(2-hydroxyethyl methacrylate) (p(HEMA)) cryogel were prepared in the presence 0.48, 0.96, and 1.92 mL of α-Glucosidase enzyme (0.06 Units/mL) solutions to obtain enzyme entrapped superporous p(HEMA) cryogels, donated as α-Glucosidase@p(HEMA)-1, α-Glucosidase@p(HEMA)-2, and α-Glucosidase@p(HEMA)-3, respectively. The enzyme entrapped p(HEMA) cryogels revealed no interruption for hemolysis and coagulation of blood rendering viable biomedical application in blood contacting applications. The α-Glucosidase@p(HEMA)-1 was found to preserve its' activity% 92.3 ± 1.4 % and higher activity% against free α-Glucosidase enzymes in 15-60℃ temperature, and 4-9 pH range. The Km and Vmax values of α-Glucosidase@p(HEMA)-1 cryogel was calculated as 3.22 mM, and 0.0048 mM/min, respectively versus 1.97 mM, and 0.0032 mM/min, for free enzymes. The α-Glucosidase@p(HEMA)-1 cryogel was found to maintained enzymatic activity more than 50 % after 10 consecutive uses, and also preserved their activity more than 50 % after 10 days of storage at 25 ℃, whereas free α-Glucosidase enzyme maintained only 1.9 ± 0.9 % activity under the same conditions.

Functions and applications of metallic and metallic oxide nanoparticles in orthopedic implants and scaffolds

Bone defects and diseases are devastating, and can lead to severe functional deficits or even permanent disability. Nevertheless, orthopedic implants and scaffolds can facilitate the growth of incipient bone and help us to treat bone defects and diseases. Currently, a wide range of biomaterials with distinct biocompatibility, biodegradability, porosity, and mechanical strength is used in bone-related research. However, most orthopedic implants and scaffolds have certain limitations and diverse complications, such as limited corrosion resistance, low cell proliferation, and bacterial adhesion. With recent advancements in materials science and nanotechnology, metallic and metallic oxide nanoparticles have become the subject of significant interest as they offer an ample variety of options to resolve the existing problems in the orthopedic industry. More importantly, these nanoparticles possess unique physicochemical and mechanical properties not found in conventional materials, and can be incorporated into orthopedic implants and scaffolds to enhance their antimicrobial ability, bioactive molecular delivery, mechanical strength, osteointegration, and cell labeling and imaging. However, many metallic and metallic oxide nanoparticles can also be toxic to nearby cells and tissues. This review article will discuss the applications and functions of metallic and metallic oxide nanoparticles in orthopedic implants and bone tissue engineering.

Enzyme-Free Glucose Biosensors Based on MoS2 Nanocomposites

High-performance glucose biosensors are highly desired for healthcare. To meet these demands, glucose biosensors, particularly enzyme-free glucose biosensors, have received much attention. Two-dimensional materials, e.g., graphene, with high surface area, excellent electrical properties, and good biocompatibility, have been the main focus of biosensor research in the last decade. This review presents the recent progress made in enzyme-free glucose biosensors based on MoS2 nanocomposites. Two different techniques for glucose detections are introduced, with an emphasis on electrochemical glucose biosensors. Challenges and future perspectives of MoS2 nanocomposite glucose biosensors are also discussed.

Synthesis of Dual-Responsive Materials with Reversible and Switchable Phase-Transition Properties for High-Performance Cellulose Enzymatic Hydrolysis

The solid-solid (immobilized cellulase-insoluble cellulose) phase cellulose hydrolysis reaction is significant in cellulosic biomass conversion processes but hindered because of its low efficiency. Herein, a smart temperature-pH dual-responsive material (D-N-N material) was prepared to be used as a carrier for cellulase recovery. This D-N-N material could undergo reversible and switchable transitions between solution, hydrogel, and solid phases. The following results were demonstrated: 1) the hydrolytic degree of this strategy could be as high as that of free cellulase in buffer solution; 2) the cellulase could be encapsulated into the D-N-N hydrogel without significant leaching and most of the cellulase activity was retained after recycling for at least 10 batches; and 3) more than 95 % of the glucose inside the hydrogel could be extracted during the hydrogel-solid transition within 1 h, which can assist in the high-efficiency separation of cellulase from glucose. The results suggested that this strategy provides a feasible platform for efficient cellulose hydrolysis and could be applied to other bio-derived reactions.

Metal-Organic Framework in Situ Post-Encapsulating DNA-Enzyme Composites on a Magnetic Carrier with High Stability and Reusability

In recent years, metal-organic frameworks (MOFs) have been extensively studied as candidate enzyme immobilization platforms. However, conventional MOF-enzyme composites usually exhibit low controllability and reusability. In this study, a novel and stable strategy for enzyme immobilization was designed by use of ZIF-8 to encapsulate in situ DNA-enzyme composites on the surface of magnetic particles (MPs). The mechanism of in situ encapsulation was discussed in detail. It was found that immobilized enzymes were involved in the growth of ZIF-8, and the DNA cross-linking agents promoted the growth of ZIF-8 on the surface of MP. The thermal, chemical, and physical stabilities of horseradish peroxidase (HRP) were all significantly enhanced after in situ encapsulation. Most importantly, this strategy was proven to be a general platform that can be used to stabilize various proteins. The in situ encapsulation strategy was expanded to immobilize a cascade of enzymes, and ZIF-8@MP_GOx-HRP possessed high selectivity and a wide linear range (25-500 μM) for glucose detection.

A Fluorescent DNA Hydrogel Aptasensor Based on the Self-Assembly of Rolling Circle Amplification Products for Sensitive Detection of Ochratoxin A

A sensitive fluorescent DNA hydrogel aptasensor based on the self-assembly of rolling circle amplification (RCA) products was developed for ochratoxin A (OTA) detection in beer. A competitive binding mode of aptamer, complementary sequence, and target was integrated into the DNA hydrogel for OTA detection. The OTA aptamer first combined with the primer to form the hybridized product. Then, in the presence of OTA, the aptamer combined with OTA, which released the primer. The released primer hybridized with the padlock probe to form a circular template, and the RCA reaction was initiated by adding ligase, polymerase, and dNTPs. The fluorescent DNA hydrogel was obtained by adding Cy3-dUTP together with dNTPs, and the fluorescence (FL) intensity of the DNA hydrogel was positively correlated with OTA concentration. Under the optimal experimental conditions, the linear range of the relationship varied from 0.05 ng/mL to 100 ng/mL with a detection limit for OTA of 0.01 ng/mL. The fluorescent DNA hydrogel aptasensor showed good specificity and stability in beer samples. Therefore, the fabricated DNA hydrogel aptasensor shows considerable potential applications in detecting OTA for food safety.

Biomineralization synthesis of a near-infrared fluorescent nanoprobe for direct glucose sensing in whole blood

A near-infrared (NIR) fluorescent nanoprobe that enables to circumvent the interference of background absorption and fluorescence in whole blood was developed for the direct sensing of blood glucose. Here, NIR fluorescent protein (iRFP) and glucose oxidase (GOx) were collectively deployed as the templates for the biomineralization of Mn2+ to prepare a NIR fluorescent nanoprobe (iRFP-GOx-MnO2 nanoparticles, iRGMs), in which the fluorescence of iRFP was effectively quenched by MnO2via energy transfer. When the iRGMs were mixed with whole blood samples, GOx can convert blood glucose into gluconic acid, as well as H2O2, which will reduce MnO2 and decompose the iRGMs. As a result, the NIR fluorescence of iRFPs was restored, providing a fluorometric assay for the direct detection of blood glucose. Owing to the high efficiency of the cascade reaction and the low background interference of the NIR fluorescence signal, accurate and rapid analysis of the glucose levels in whole blood samples was achieved using the iRGMs. Moreover, an iRGM-based paper device that only requires 5 microliters of samples was also demonstrated in the direct assay of blood glucose without any pretreatment, affording an alternative approach for the accurate monitoring of blood glucose levels.

The design and characterization of a hypersensitive glucose sensor: two enzymes co-fixed on a copper phosphate skeleton

A new glucose sensor GOx&DhHP-6–Cu₃(PO₄)₂ showed the best catalytic ability at a neutral temperature and pH.

Enzymatic Noncovalent Synthesis of Supramolecular Soft Matter for Biomedical Applications

Enzymatic noncovalent synthesis (ENS), a process that integrates enzymatic reactions and supramolecular (i.e., noncovalent) interactions for spatial organization of higher-order molecular assemblies, represents an emerging research area at the interface of physical and biological sciences. This review provides a few representative examples of ENS in the context of supramolecular soft matter. After a brief comparison of enzymatic covalent and noncovalent synthesis, we discuss ENS of man-made molecules for generating supramolecular nanostructures (e.g., supramolecular hydrogels) in cell-free conditions. Then, we introduce ENS in a cellular environment. To illustrate the unique merits for applications, we discuss intercellular, peri- or intracellular, and subcellular ENS for cell morphogenesis, molecular imaging, cancer therapy, and targeted delivery. Finally, we provide an outlook on the potential of ENS. We hope that this review offers a new perspective for scientists who develop supramolecular soft matter to address societal needs at various frontiers.

Robust magnetic double-network hydrogels with self-healing, MR imaging, cytocompatibility and 3D printability

Herein, we have fabricated a novel robust self-healing magnetic double-network hydrogel by multiple interactions between bondable magnetic Fe3O4 and chitosan-polyolefin matrix, and the hydrogel also exhibits an excellent magnetogenic effect and MR imageability. The practical potential of the magnetic double-network hydrogel is further revealed by its 3D-printing performance.