Antifouling hydrogel-coated magnetic nanoparticles for selective isolation and recovery of circulating tumor cells

For reliable downstream molecular analysis, it is crucially important to recover circulating tumor cells (CTCs) from clinical blood samples with high purity and viability. Herein, magnetic nanoparticles coated with an antifouling hydrogel layer based on the polymerization method were developed to realize cell-friendly and efficient CTC capture and recovery. Particularly, the hydrogel layer was fabricated by zwitterionic sulfobetaine methacrylate (SBMA) and methacrylic acid (MAA) cross-linked with N,N-bis(acryloyl)cystamine (BACy), which could not only resist nonspecific adhesion but also gently recover the captured cells by glutathione (GSH) responsiveness. Moreover, the anti-epithelial cell adhesion molecule (anti-EpCAM) antibody was modified onto the surface of the hydrogel to provide high specificity for CTC capture. As a result, 96% of target cells were captured in the mimic clinical blood samples with 5-100 CTCs per mL in 25 min of incubation time. After the GSH treatment, about 96% of the obtained cells were recovered with good viability. Notably, the hydrogel-coated magnetic nanoparticles were also usefully applied to isolate CTCs from the blood samples of cancer patients. The favorable results indicate that the hydrogel-modified magnetic nanoparticles may have a promising opportunity to capture and recover CTCs for subsequent research.

Anti-PD-L1 DNA aptamer antagonizes the interaction of PD-1/PD-L1 with antitumor effect

Tumor immune evasion enables cancer cells to escape destruction by the immune system, which causes poor prognosis and overall survival of some tumor patients. The binding of PD-L1 on tumor cells to PD-1 on T cells suppresses T cell function, and the axis is considered one of the major pathways mediating tumor cells to evade immune surveillance. The PD-L1 ligation of T cells has a profound inhibitory effect on the growth, cytokine secretion, and development of cytotoxicity. Aptamers, known as chemical antibodies, are single-stranded oligonucleotides with high affinity. In this work, we take a cell-SELEX with the engineered PD-L1-expressing cells as a target to obtain the aptamer, designated PL1, which specifically binds to PD-L1 with a Kd value of 95.73 nM, resulting in the inhibition of PD-1/PD-L1. The aptamer PL1 could restore the proliferation and IFN-γ rescue from the T cell inhibited by the PD-1/PD-L1 axis, and inhibit the growth of the CT26 colon carcinoma. The similar tumor inhibition efficacy and binding capacity of the aptamer PL1 as an antibody indicate that the aptamer PL1 can serve as an alternative therapeutic agent for cancer immunotherapy since the use of antibodies is often restricted by high cost, large size and poor tumor penetration.

Selective capture of circulating tumor cells by antifouling nanostructure substrate made of hydrogel nanoparticles

The detection and analysis of circulating tumor cells (CTCs) from cancer patients' blood samples present a powerful means to monitor cancer progression. In this work, an antifouling nanostructure substrate made of hydrogel nanoparticles was fabricated for an effective capture of CTCs from the blood samples. The hydrogel nanoparticles were synthesized by zwitterionic sulfobetaine methacrylate (SBMA), methacrylic acid (MAA) and N, N'-methylene bisacrylamide (MBA) through a simple polymerization. SBMA could provide an effective antifouling layer for the substrate to prevent nonspecific cell adhesion, MAA could afford active carboxyl groups for the immobilization of antibody to achieve specific CTC capture, and the nanostructured surface could improve the interaction of the target cells with the antibody modified substrate surface to enhance the capture efficiency of CTCs. Moreover, it was not necessary to further modify the antifouling molecules on the hydrogel nanoparticle substrate's surface, reducing the complexity and difficulty of the substrate preparation. The results showed that about 87 % of target cells (MCF-7 cells) were captured on the antibody modified hydrogel nanoparticle substrate. In contrast, the substrate showed little adhesive capacity for the nonspecific cells (K562 cells), and only 0.15 % of cells were captured. And 98 % of the captured cells kept good cell viability. Finally, 1-32 CTCs/mL were detected from the blood samples of five cancer patients, while no CTC was found in five healthy samples. It is envisaged that the new hydrogel nanostructure substrate is capable of capturing CTCs efficiently and specifically from patient blood samples to be used in cancer treatment.

Aptamer-based nanostructured interfaces for the detection and release of circulating tumor cells

Analysis of circulating tumor cells (CTCs) can provide significant clinical information for tumors, which has proven to be helpful for cancer diagnosis, prognosis monitoring, treatment efficacy, and personalized therapy. However, CTCs are an extremely rare cell population, which challenges the isolation of CTCs from patient blood. Over the last few decades, many strategies for CTC detection have been developed based on the physical and biological properties of CTCs. Among them, nanostructured interfaces have been widely applied as CTC detection platforms to overcome the current limitations associated with CTC capture. Furthermore, aptamers have attracted significant attention in the detection of CTCs due to their advantages, including good affinity, low cost, easy modification, excellent stability, and low immunogenicity. In addition, effective and nondestructive release of CTCs can be achieved by aptamer-mediated methods that are used under mild conditions. Herein, we review some progress in the detection and release of CTCs through aptamer-functionalized nanostructured interfaces.

Necessities, opportunities, and challenges for tympanic membrane perforation scaffolding-based bioengineering

Tympanic membrane (TM) perforation is a global clinical dilemma. It occurs as a consequence of object penetration, blast trauma, barotrauma, and middle ear diseases. TM perforation may lead to otitis media, retraction pockets, cholesteatoma, and conductive deafness. Molecular therapies may not be suitable to treat perforation because there is no underlying tissue matrix to support epithelium bridging. Chronic perforations are usually reconstructed with autologous grafts via surgical myringoplasty. Surgical treatment is uncomfortable for the patients. The grafting materials are not perfect because they produce an opaque membrane, fail in up to 20% of cases, and are suboptimal to restore acoustic function. Millions of patients from developing parts of the world have not got access to surgical grafting due to operational complexities, lack of surgical resources, and high cost. These shortcomings emphasize bioengineering to improve placement options, healing rate, hearing outcomes, and minimize surgical procedures. This review highlights cellular, structural, pathophysiological, and perforation specific determinants that affect healing, acoustic and surgical outcomes; and integrates necessities relevant to bioengineered scaffolds. This study further summarizes scaffolding components, progress in scaffolding strategies and design, and engenders limitations and challenges for optimal bioengineering of chronic perforation.

NIR-laser-triggered gadolinium-doped carbon dots for magnetic resonance imaging, drug delivery and combined photothermal chemotherapy for triple negative breast cancer

BACKGROUND

Owing to high genetic diversities of tumor cells and low response rate of standard chemotherapy, patients with triple negative breast cancer (TNBC) have short progression-free survivals and poor outcomes, which need to explore an effective approach to improve therapeutic efficacy.

METHODS

Novel gadolinium doped carbon dots (Gd@CDs) have been designed and prepared through hydrothermal method with 3,4-dihydroxyhydrocinnamic acid, 2,2'-(ethylenedioxy)bis(ethylamine) and gadolinium chloride. The synthesized nanostructures were characterized. Taking advantage of good biocompatibility of Gd@CDs, a nanoplatform based on Gd@CDs has been developed to co-deliver chemotherapy drug doxorubicin hydrochloride (Dox) and a near-infrared (NIR) photothermal agent, IR825 for magnetic resonance imaging (MRI) guided photothermal chemotherapy for TNBC.

RESULTS

The as-synthesized Dox@IR825@Gd@CDs displayed favorable MRI ability in vivo. Upon NIR laser irradiation, Dox@IR825@Gd@CDs could convert the NIR light to heat and efficiently inhibit tumor growth through photothermal chemotherapy in vitro and in vivo. Additionally, the impact of photothermal chemotherapy on the murine motor coordination was assessed by rotarod test. Dox@IR825@Gd@CDs presented low toxicity and high photothermal chemotherapy efficiency.

CONCLUSION

A noble theranostic nanoplatform (Dox@IR825@Gd@CDs) was developed that could be tailored to achieve loading of Dox and IR825, intracellular delivery, favorable MRI, excellent combination therapy with photothermal therapy and chemotherapy to enhance therapeutic effect against TNBC cells. This study will provide a promising strategy for the development of Gd-based nanomaterials for MRI and combinational therapy for TNBC.

The modulation effect of charge transfer on photoluminescence in metal-organic frameworks

Metal-organic framework (MOF) nanomaterials with distinct matrix coordination-induced emission (MCIE) and quenching (MCIQ) effects were designed. The MOF structure can effectively restrict the intramolecular rotation of the organic linkers and enable the excited nanoparticles to exhibit the MCIE effect. However, if the ligand-to-metal charge transfer (LMCT) process occurs in the MOF structure, the fluorescence will be quenched and the excitation energy released in the form of non-radiative energy. When an electron donor is added to block the LMCT process, as expected, the fluorescence of the MOF nanomaterials is recovered. Therefore, the intramolecular LMCT process acts as a fluorescent switch in MOF nanomaterials that can effectively quench or enable their fluorescence. Additionally, the LMCT process is not affected by the morphology of the coordination compounds, even when the MOF nanomaterials are ground into amorphous structures. These results confirm that the fluorescence of MOF nanomaterials can be regulated by the LMCT process. This study has significance for guiding the design and synthesis of MOF nanomaterials with photoluminescence properties.

Redox-triggered aggregation of ESIONPs with switchable T1 to T2 contrast effect for T2-weighted magnetic resonance imaging

Magnetic resonance imaging (MRI) contrast agents (CAs) have drawn increasing attention in cancer diagnosis. However, since the signals they generate are always "on" and may bring interfering background signals to the region of interest, their selectivity and sensitivity need further improvement. Herein, extremely small iron oxide nanoparticles (ESIONPs) conjugated through a disulfide bond with polyethylene glycol (PEG) that is terminally modified with folic acid (FA), namely ESIONPs-s-s-PEG-FA, were designed and synthesized to target tumor tissues and selectively activate the T2 MRI contrast effect in the reducing environment of tumor cells. Due to the breakage of disulfide bonds by the high glutathione (GSH) concentration in tumor cells, the hydrophilic PEG chains detached from the surface of ESIONPs, which led to the aggregation of ESIONPs and the activation of the T2 contrast effect. In vitro results showed that ESIONPs-s-s-PEG-FA could effectively target tumors to assemble in the reductive environment and switch from a T1 contrast agent (CA) to a T2 one. Furthermore, MRI in tumor-bearing mice also indicated the obvious targeting capacity and the "turn on" of the T2 contrast effect. In addition, the results of the biosafety assay suggest that the tumor-targeted T1/T2 switchable CA is equipped with favorable biocompatibility for cancer diagnosis.

The isolation of a DNA aptamer to develop a fluorescent aptasensor for the thiamethoxam pesticide

Aptamers, which are called chemical antibodies for their high affinity and specificity to targets, have great potential as analytical tools to detect pesticides. In this work, a DNA aptamer for thiamethoxam was isolated by an improved SELEX (systematic evolution of ligands by exponential enrichment) strategy, in which the ssDNA library was fixed on streptavidin-agarose beads through a short biotin labeled complementary strand. After 13 rounds of selection, the random ssDNA pool was successfully enriched. Three sequences were chosen as aptamer candidates through sequencing and analysis and were transformed into fluorescent probes to evaluate their interactions with thiamethoxam. A fluorescent turn-on aptasensor for thiamethoxam based on the best aptamer (FAM-Thi13) and a short quenching strand were further designed and showed a quantitative linear range from 10 to 1000 nM with a detection limit of 1.23 nM for thiamethoxam. Molecular docking and molecular dynamics were used to investigate the binding site of the main probe of the aptasensor (FAM-Thi13) and thiamethoxam. Satisfactory results were also obtained in quantifying thiamethoxam in environmental water samples by the developed fluorescent aptasensor.

Tannic Acid (TA)-Functionalized Magnetic Nanoparticles for EpCAM-Independent Circulating Tumor Cell (CTC) Isolation from Patients with Different Cancers

The majority of current methods of isolating circulating tumor cells (CTCs) rely on a biomarker. However, the isolation efficiency may be compromised due to the heterogeneity of CTCs. In this work, a simple and broad-spectrum method is established to efficiently isolate the heterogeneous CTCs from patient blood samples using tannic acid (TA)-functionalized magnetic nanoparticles (MNPs). The TA-functionalized MNPs (MNPs-TA) inhibit the nonspecific adhesion of peripheral blood mononuclear cell (PBMC) and enhance cancer cell capture, resulting from the unique interaction between TA and glycocalyx on cancer cells. The MNPs-TA was demonstrated to effectively capture seven kinds of cancer cells (HeLa, PC-3, T24, MAD-MB-231, MCF-7, HT1080, A549) from artificial samples (62.3-93.7%). Moreover, this epithelial cell adhesion molecule (EpCAM)-independent CTC isolation method was also tested using clinical blood samples from patients with different cancers (21 patients), which may provide a universal tool to detect CTCs in the clinic.

Construction of a Silk Fibroin/Polyethylene Glycol Double Network Hydrogel with Co-Culture of HUVECs and UCMSCs for a Functional Vascular Network

The success of complex tissue and internal organ reconstruction relies principally on the fabrication of a 3D vascular network, which guarantees the delivery of oxygen and nutrients in addition to the disposal of waste. In this study, a rapidly forming cell-encapsulated double network (DN) hydrogel is constructed by an ultrasonically activated silk fibroin network and bioorthogonal-mediated polyethylene glycol network. This DN hydrogel can be solidified within 10 s, and its mechanical property gradually increases to ∼20 kPa after 30 min. This work also demonstrates that coencapsulation of human umbilical vein endothelial cells (HUVECs) and umbilical cord-derived mesenchymal stem cells (UCMSCs) into the DN hydrogel can facilitate the formation of more mature vessels and complete the capillary network in comparison with the hydrogels encapsulated with a single cell type both in vitro and in vivo. Taking together, the DN hydrogel, combined with coencapsulation of HUVECs and UCMSCs, represents a strategy for the construction of a functional vascular network.

Engineered Fe3O4-based nanomaterials for diagnosis and therapy of cancer

Recent developments of Fe₃O₄ NP-based theranostic nanoplatforms and their applications in tumor-targeted imaging and therapy.

Ni-Nitrilotriacetic Acid Affinity SELEX Method for Selection of DNA Aptamers Specific to the N-Cadherin Protein

Nucleic acid aptamers are single-stranded oligonucleotides that may be evolved for affinity and specificity for their targets and can be easily produced, regenerated, and stabilized. In this study, we adapted Ni-NTA (nickle-charged nitrilotriacetic acid) affinity-chromatography in the development of single-stranded DNA aptamers against N-cadherin protein by systematic evolution of ligands by exponential enrichment (SELEX). After ten rounds of selection, two aptamers, designated NS13 and NC23, were selected, which showed low dissociation constants of 93 and 174 nM, respectively. The 5'-carboxyfluorescein-labeled NS13 was used for the sensitive detection of N-cadherin protein by the enzyme-linked oligonucleotide assay (ELONA) method.

Isolation of DNA aptamers targeting N-cadherin and high-efficiency capture of circulating tumor cells by using dual aptamers

Circulating tumor cells (CTCs) acquire mesenchymal markers (e.g., N-cadherin) and lose epithelial markers (e.g., epithelial cell adhesion molecule, EpCAM) during the epithelial-mesenchymal transition (EMT) and are therefore ideal biomarkers of tumor metastasis. However, it is still a challenge to efficiently capture and detect circulating tumor cells with different phenotypes simultaneously. In this work, to obtain aptamers targeting N-cadherin in the native conformation on live cells, we established stable N-cadherin overexpressing cells (N-cadherin cells) and used these cells to identify a panel of N-cadherin-specific aptamers through the cell-SELEX approach. Two aptamer candidates obtained after 12 rounds of selection showed a low equilibrium dissociation constant in the nanomolar range, indicating high binding affinity. The truncated aptamer candidate NC3S showed the highest binding affinity to N-cadherin cells with a low Kd value of 20.08 nM. The SYL3C aptamer was reported to target cancer cell surface biomarker EpCAM. Then, we synthesized two kinds of aptamer-modified magnetic nanoparticles (SYL3C-MNPs and NC3S-MNPs). Both SYL3C and NC3S aptamers possess excellent capture specificity and efficiency for the target cells. The aptamer-MNP cocktail exhibits a considerable capture efficiency and sensitivity for rare cancer cells of epithelial and mesenchymal phenotypes. Furthermore, no CTCs were found in blood samples from healthy donors, while CTCs were successfully isolated by using the aptamer-MNP cocktail for 15 out of 16 samples collected from patients. In summary, the two kinds of aptamer-modified MNPs could be utilized as a promising tool for capturing CTCs from clinical samples.

Tumor Acid Microenvironment-Triggered Self-Assembly of ESIONPs for T1/T2 Switchable Magnetic Resonance Imaging

Smart magnetic resonance imaging (MRI) contrast agents (CAs), whose MRI contrasting enhancement is variable in response to the specific stimulus from tumor tissues, possess great potential in precise tumor diagnosis. Herein, we design a type of extremely small iron oxide nanoparticle (ESIONP)-based pH-responsive system for activatable T₂ MRI in the tumor acid microenvironment. The ESIONP system is composed of ESIONP-PEG-PGA and ESIONP-PEG-PDC, which were respectively constructed through the surface modification with poly (l-glutamic acid) (PGA) and poly(N-{N'-[N″-(2-carbox aminoethyl)]-2-aminoethyl}glutamide) (PDC) on the surface of ESIONP. The pH-responsive system exhibits the dispersed state under the neutral condition, and when it is exposed to the weakly acid environment, ESIONP-PEG-PDC switches from the neutral to positive charge, finally leading to the aggregation by the electrostatic interaction between the positively charged ESIONP-PEG-PDC and negatively charged ESIONP-PEG-PGA. On the basis of the aggregation, the T₁ contrasting effect of the pH-responsive system switches to a T₂ contrasting effect, which can be employed to realize the selective enhancement of imaging contrast at the tumor location owing to the weakly acid microenvironment. Moreover, on the basis of size increase originated from the aggregation effect, the residence time of extremely small iron oxide nanoparticles (ESIONPs) in the tumor site is effectively prolonged, which is beneficial for the MRI of tumors. Therefore, the pH-responsive system based on the ESIONPs is a potential smart MRI contrast agent for accurate tumor diagnosis.

Isolation of DNA Aptamer Targeting PD-1 with an Antitumor Immunotherapy Effect

Immune checkpoints play a vital role in regulating T cell responses. Programmed cell death 1 (PD-1), a key inhibitory immune-checkpoint receptor, negatively regulates the human immune response. Anti-PD-1 therapy is an immune-checkpoint inhibition therapy, which is a progressing clinical strategy in treating various human cancers. Aptamers, called "chemical antibodies", have several virtues, including better tissue penetration, lower immunogenicity, and ease of production. Here, after 10 rounds of selection using engineered cells with PD-1 overexpression as target cells, we successfully isolated four anti-PD-1 aptamer candidates using cell-SELEX (systematic evolution of ligands by exponential enrichment) procedure. Among them, the candidate PD4S showed the highest affinity with an equilibrium dissociation constant (K_d) of 10.3 nM and rescued the T cell function suppressed by PD-1/PD-L1. Treatment of PD4S in the CT26 carcinoma model showed an antitumor effect. Together, the anti-PD-1 aptamer PD4S could be applied as an alternative agent in immunotherapy.

Synergistic regulation of longitudinal and transverse relaxivity of extremely small iron oxide nanoparticles (ESIONPs) using pH-responsive nanoassemblies

Extremely small iron oxide nanoparticles (ESIONPs), as a kind of the special T1 magnetic resonance imaging (MRI) contrast agent that can provide T1 contrasting enhancement since their magnetically disordered shells are dominant compared to their magnetic cores and have powerful potential for constructing stimuli-responsive contrast agents (CAs) to realize precise the tumor diagnosis with high specificity and sensitivity. The stimuli-responsive function of ESIONPs-based CAs can be directly endowed through the synergistic regulation of the longitudinal and transverse relaxivity (r1 and r2) of ESIONPs. However, the systematical investigation for the synergistic regulation of r1 and r2 of ESIONPs is quite lacking. Herein, based on the relaxivity theories, three kinds of ESIONPs-based nanoassemblies with pH-responsiveness were designed and constructed to explore the possibility of various synergistic regulations on r1 and r2. When three kinds of ESIONPs-based nanoassemblies were converted to dissociated ones under a weak acid environment, ESIONPs micelle could realize a synergistic regulation of the single r2 decrease along with the stable r1, while gold nanoparticles-ESIONPs (AuNPs-ESIONPs) vesicle could provide a synergistic regulation comprising the single r1 increase along with the stable r2, and ESIONPs vesicle could offer a synergistic regulation involving the r2 decrease together with the r1 increase. Moreover, all the synergistic regulations on r1 and r2 were efficient strategies to fabricate ESIONPs-based CAs with the stimuli-responsive function. These systematic and feasible synergistic regulations of r1 and r2 may guide and promote the development of ESIONPs-based stimuli-responsive CAs for the highly sensitive and specific tumor diagnosis.

Dual-Stimuli-Responsive Multifunctional Gd2Hf2O7 Nanoparticles for MRI-Guided Combined Chemo-/Photothermal-/Radiotherapy of Resistant Tumors

The design and synthesis of a novel generation of a nanoscaled platform with imaging-guided therapy remain a real challenge. It can not only improve the imaging sensitivity of tumor tissues for guiding all kinds of treatments but also reduce the harm for healthy tissues. Here, polydopamine (PDA), polyethylene glycol (PEG), and c(RGDyK) peptide (RGD)-modified and cisplatin-loaded Gd₂Hf₂O₇ nanoparticles (Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs) are designed for magnetic resonance imaging (MRI)-guided combined chemo-/photothermal-/radiotherapy of resistant tumors. The as-prepared NPs display high relaxivity (r₁ = 38.28 mM^-1 s^-1) as an MRI contrast agent because of their ultrasmall size and surface modification with polyacrylic acid and PDA. Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs exhibit pH and NIR dual-stimuli responsiveness for cisplatin release. Based on competent NIR absorption and high X-ray attenuation efficiency, Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs show potential photothermal effect by exposing to an 808 nm NIR laser and significantly improve the generation of reactive oxygen species after X-ray radiation. Combined chemo-/photothermal-/radiotherapy can effectively treat the resistant A549R cells, providing the enhanced therapeutic efficiency to cancer tissues and the reduced side effect to healthy tissues. Furthermore, Gd₂Hf₂O₇@PDA@PEG-Pt-RGD NPs present no obvious toxicity during the treatment, which demonstrates the potential as an efficient MRI-guided combined chemo-/photothermal-/radiotherapy nanoplatform for drug-resistant tumors.

Identifying a novel 5-gene signature predicting clinical outcomes in acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is the most common type of acute leukemia and biologically heterogeneous diseases with poor prognosis. Thus, we aimed to identify prognostic markers to effectively predict the prognosis of AML patients and eventually guide treatment.

METHODS

Prognosis-associated genes were determined by Kaplan-Meier and multivariate analyses using the expression and clinical data of 173 AML patients from The Cancer Genome Atlas database and validated in an independent Oregon Health and Science University dataset. A prognostic risk score was computed based on a linear combination of 5-gene expression levels using the regression coefficients derived from the multivariate logistic regression model. The classification of AML was established by unsupervised hierarchical clustering of CALCRL, DOCK1, PLA2G4A, FCHO2 and LRCH4 expression levels.

RESULTS

High FCHO2 and LRCH4 expression was related to decreased mortality. While high CALCRL, DOCK1, PLA2G4A expression was associated with increased mortality. The risk score was predictive of increased mortality rate in AML patients. Hierarchical clustering analysis of the five genes discovered three clusters of AML patients. The cluster1 AML patients were associated with lower cytogenetics risk than cluster2 or 3 patients, and better prognosis than cluster3 patients (P values < 0.05 for all cases, fisher exact test or log-rank test).

CONCLUSION

The gene panel comprising CALCRL, DOCK1, PLA2G4A, FCHO2 and LRCH4 as well as the risk score may offer novel prognostic biomarkers and classification of AML patients to significantly improve outcome prediction.

Nanocomposite hydrogels for tissue engineering applications

Tissue engineering is an important field of regenerative medicine, which combines scaffolds and cell transplantation to develop substitute tissues and/or promote tissue regeneration. Hydrogels, a three-dimensional network with high water content and biocompatibility, have been widely used as scaffolds to mimic the structure and properties of tissues. However, the low mechanical strength and limited functions of traditional hydrogels greatly limited their applications in tissue engineering. Recently, nanocomposite hydrogels, with its advantages of high mechanical property and some unique properties (such as electrical conductivity, antibacterial, antioxidation, magnetic responsiveness), have emerged as the most versatile and innovative technology, which provides a new opportunity as a unique tool for fabricating hydrogels with excellent properties. In this review, we summarize the recent advances in fabricating nanocomposite hydrogels and their applications in tissue engineering. In addition, the future and prospects of nanocomposite hydrogels for tissue engineering are also discussed.

Acid-facilitated G-quadruplex/hemin DNAzymes: accompanied by the assembly of quadruplex supramolecules

Four types of quadruplex supramolecules containing G-quadruplex (G4)-I-motif interfaces were assembled under slightly acidic conditions, which can interact with hemin to form I-motif-linked G4/hemin DNAzymes. Our data demonstrated that some I-motif-linked DNAzymes are highly acid-dependent due to the stabilization of hemiprotonated cytosine-cytosine (C˙CH⁺) pairs for the G4 units.