Abundant Binding Sites Research Articles

Host-guest mediated recognition and rapid extraction of Fusarium mycotoxins in cereals by nickel ferrite magnetic calix[4]arene-derived covalent organic framework fabricated in room-temperature

Fusarium mycotoxins are toxic secondary fungal metabolites and widely distributed in cereals. Herein, a nickel ferrite magnetic calix[4]arene-derived covalent organic framework (NiFe2O4@CX4-COF) was meticulously designed and synthesized using a room-temperature method for the enrichment of mycotoxins. The CX4-COF exhibited a porous crystalline network with an eclipsed AA-stacking configuration. The ingenious integration of NiFe2O4, supramolecular calix[4]arene and COF contributed to host-guest mediated recognition, size-selectivity and high adsorption capacity, rapidly reaching adsorption equilibrium within only 3 min. Simulation calculations revealed that the host-guest interaction, size effect and abundant binding sites facilitated synergistically recognize and capture mycotoxins. NiFe2O4@CX4-COF has successfully applied for simultaneous extraction and analysis of mycotoxins in cereals, achieving negligible matrix effects (−14% to 13%), high sensitivity (LODs of 0.003–0.014 μg/L) and satisfactory recoveries (74.4%–116%). This work provides a prospective platform for constructing tailored macrocycle-based COFs under mild conditions for precise recognition and accurate analysis of trace hazardous substances in food.

Construction of Highly Porous and Robust Hydrogen-Bonded Organic Framework for High-Capacity Clean Energy Gas Storage.

Development of highly porous and robust hydrogen-bonded organic frameworks (HOFs) for high-pressure methane and hydrogen storage remains a grand challenge due to the fragile nature of hydrogen bonds. Herein, we report a strategy of constructing the double-walled framework to target highly porous and robust HOF (ZJU-HOF-5a) for extraordinary CH4 and H2 storage. ZJU-HOF-5a features a minimized twofold interpenetration with double-walled structure, in which multiple supramolecular interactions are existed between the interpenetrated walls. This structural configuration can notably enhance the framework robustness while maintaining its high porosity, affording one of the highest gravimetric and volumetric surface areas of 3102 m2 g-1 and 1976 m2 cm-3 among the reported HOFs so far. ZJU-HOF-5a thus exhibits an extremely high volumetric H2 uptake of 43.6 g L-1 at 77 K/100 bar and working capacity of 41.3 g L-1 under combined swing conditions (77 K/100 bar→160 K/5 bar), and also impressive methane storage performance with a 5-100 bar working capacity of 187 (or 159) cm3 (STP) cm-3 at 270 K (or 296 K), outperforming most of the reported porous organic materials. Single-crystal X-ray diffraction studies on CH4-loaded ZJU-HOF-5a reveal that abundant supramolecular binding sites combined with ultrahigh porosities account for its high CH4 storage capacities. Combined with high stability, super-hydrophobicity, and easy recovery, ZJU-HOF-5a is placed among the most promising materials for H2 and CH4 storage applications.

CMAGN: circRNA–miRNA association prediction based on graph attention auto-encoder and network consistency projection

Background: As noncoding RNAs, circular RNAs (circRNAs) can act as microRNA (miRNA) sponges due to their abundant miRNA binding sites, allowing them to regulate gene expression and influence disease development. Accurately identifying circRNA–miRNA associations (CMAs) is helpful to understand complex disease mechanisms. Given that biological experiments are time consuming and labor intensive, alternative computational methods to predict CMAs are urgently needed. Results: This study proposes a novel computational model named CMAGN, which incorporates several advanced computational methods, for predicting CMAs. First, similarity networks for circRNAs and miRNAs are constructed according to their sequences. Graph attention autoencoder is then applied to these networks to generate the first representations of circRNAs and miRNAs. The second representations of circRNAs and miRNAs are obtained from the CMA network via node2vec. The similarity networks of circRNAs and miRNAs are reconstructed on the basis of these new representations. Finally, network consistency projection is applied to the reconstructed similarity networks and the CMA network to generate a recommendation matrix. Conclusion: Five-fold cross-validation of CMAGN reveals that the area under ROC and PR curves exceed 0.96 on two widely used CMA datasets, outperforming several existing models. Additional tests elaborate the reasonability of the architecture of CMAGN and uncover its strengths and weaknesses.

A novel highly selective Fe@UiO-67-BDA/GCE sensor for efficient detecting Hg2+

A three-dimensional UiO-67-BDA with various pore structures and abundant active binding sites is constructed, and Fe@UiO-67-BDA composites with electrochemical sensing and recognition performance were further prepared by successfully loading Fe3+ ions. The different modified electrodes (Fe@UiO-67-BDA/GCE, UiO-67-BDA/GCE, Fe/GCE) and the bare electrode (GCE) were also characterized in terms of basic structure and electrochemistry, and it was found that the basic structure and electrochemical performances of Fe@UiO-67-BDA/GCE were better than those of the remaining three electrodes, with good selectivity, reproducibility and stability. And the Fe@UiO-67-BDA/GCE sensor with good electrochemical performance was constructed under the optimal working potential (Epa = 0.59 V) and experimental conditions, which was utilized to rapidly and accurately detect heavy metal ions Hg2+ by the DPV method, with a detection limit of up to 1.642 × 10−9 M. In addition, the electrochemical behavior mechanism of the Fe@UiO-67- BDA/GCE sensor was investigated. Finally, the sensor was applied to detect cosmetic heavy metal ions, and the experimental results also showed high reliability and practicality. Therefore, MOFs composite material is applied to the field of electrochemistry, because of its simple operation technology, fast detection speed and high sensitivity, so that it has a greater application prospect.

An electrochemical sensor based on porous heterojunction hollow NiCo-LDH/Ti3C2Tx MXenes composites for the detection of quercetin in natural plants.

Cubic hollow-structured NiCo-LDH was synthesized using a solvothermal method. Subsequently, clay-like Ti3C2Tx MXenes were electrostatically self-assembled with NiCo layered double hydroxides (NiCo-LDH) to form composites featuring three-dimensional porous heterostructures. The composites were characterized using SEM, TEM, XRD, XPS, and FT-IR spectroscopy. Ti3C2Tx MXenes exhibit excellent electrical conductivity and hydrophilicity, providing abundant binding sites for NiCo-LDH, thereby promoting an increase in ion diffusion channels. The formation of three-dimensional porous heterostructural composites enhances charge transport, significantly improving sensor sensitivity and response speed. Consequently, the sensor demonstrates excellent electrochemical detection capabilityfor quercetin (Qu), with a detection range of 0.1-20 µM and a detection limit of 23 nM. Additionally, it has been applied to the detection of Qu in natural plants such as onion, golden cypress, and chrysanthemum. The recovery ranged from 97.6 to 102.28%.

Construction of Highly Porous and Robust Hydrogen‐Bonded Organic Framework for High‐Capacity Clean Energy Gas Storage

Development of highly porous and robust HOFs for high‐pressure methane and hydrogen storage remains a grand challenge due to the fragile nature of hydrogen bonds. Herein, we report a strategy of constructing double‐walled framework to target highly porous and robust HOF (ZJU‐HOF‐5a) for extraordinary CH4 and H2 storage. ZJU‐HOF‐5a features a minimized twofold interpenetration with double‐walled structure, in which multiple supramolecular interactions are existed between the interpenetrated walls. This structural configuration can notably enhance the framework robustness while maintaining its high porosity, affording one of the highest gravimetric and volumetric surface areas of 3102 m2 g−1 and 1976 m2 cm−3 among the reported HOFs so far. ZJU‐HOF‐5a exhibits an extremely high volumetric H2 uptake of 43.6 g L−1 at 77 K/100 bar and working capacity of 41.3 g L−1 under combined swing conditions, and also impressive methane storage performance with a 5−100 bar working capacity of 187 (or 159) cm3 cm−3 at 270 K (or 296 K). SCXRD studies on CH4‐loaded ZJU‐HOF‐5a reveal that abundant supramolecular binding sites combined with ultrahigh porosities account for its high CH4 storage capacities. Combined with high stability, super‐hydrophobicity, and easy‐recovery, ZJU‐HOF‐5a is placed among the most promising materials for H2 and CH4 storage applications.

Highly porous P(DVB-AMPS) copolymer with tailored surface engineering for efficient fluoride capture from water

Surface engineering, especially surface hydrophilicity and active binding sites are crucial for porous polymers in the removal of fluoride ions from water. Herein, a novel P(DVB-AMPS) copolymer with tailored surface engineering was designed through a one-step polymerization method by incorporating diethylene-benzene (DVB) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). AMPS endows abundant active binding sites and provides P(DVB-AMPS) with both hydrophilicity and affinity for fluoride ions, while the monomer DVB acting as a crosslinker, facilitating pore generating. The surface hydrophilicity of P(DVB-AMPS) could be easily tuned by increasing the amounts of AMPS with the contact angle decreased from 126° (PDVB) to 52°. Furthermore, P(DVB-AMPS) material maintains a large specific surface area of 428 m2 · g[Formula: see text] and preserves its highly porous structure. P(DVB-AMPS) exhibits an efficient adsorption capacity (51.9 mg · g[Formula: see text]) and a rapid adsorption rate (6.83 mg · g[Formula: see text] · min[Formula: see text]), which demonstrates competitive performance compared with previous reports. Importantly, the material possesses highly selective adsorption toward fluoride. The excellent adsorption performance of P(DVB-AMPS) is attributed to the high porosity, improved surface hydrophilicity and active binding sites. This work not only provides a new strategy for designing high-performance adsorbents but also offers a novel polymer material for the efficient capture of fluoride ions from water.

Ultrasonic preparation of fluorinated functionalised magnetic covalent organic frameworks for adsorption and removal of tetrabromobisphenol A

Tetrabromobisphenol A (TBBPA) was a widely used brominated flame retardant, and had attracted widespread attention from researchers due to its potential adverse effects on ecosystems and human health. Therefore, to eliminate the negative effects of TBBPA, methods for the adsorption and removal of TBBPA are urgently needed. In this work, the fluorine-functionalised magnetic covalent organic frameworks (Fe3O4@TFAPT-TFPA@COF) were first prepared through a simple and rapid ultrasound method to efficiently adsorpt and remove TBBPA. Firstly, a pre-modification strategy was used to modify fluorine functional groups onto amine monomers via superacid catalyzed trimerization. Then, amine and aldehyde monomers undergo Schiff base reaction smoothly to form a COF layer coated on the surface of Fe3O4 nanoparticles. The characterisation results indicated that the prepared Fe3O4@TFAPT-TFPA@COF had a high surface area, porosity, crystallinity and abundant F-containing binding sites. Additionally, the adsorption process of prepared Fe3O4@TFAPT-TFPA@COF complied with pseudo-second-order kinetics and the Langmuir adsorption model. It had a large adsorption capacity (107.5 mg g−1), could effectively remove tetrabromobisphenol A within 4 minutes and had excellent regeneration ability within eighth repetitions. Finally, tetrabromobisphenol A was efficiently removed by a small separation column loaded with Fe3O4@TFAPT-TFPA@COF, achieving levels below the detection limit (< 0.05 mg L−1) and providing practical application value for the real-time removal of TBBPA. The main mechanisms promoting the excellent adsorption performance of TBBPA were through halogen bonds, electrostatic interactions, π-π stacking, and hydrogen bonding interactions, providing potential reference value for the adsorption ability and mechanism of TBBPA in other applications.

Synthesis and investigation of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid copolymer-modified graphene oxide nanomaterials with intensive viscosification capacity: An experimental and molecular dynamics study

The polymer-modified nanomaterials with spontaneously generated cross-linked network greatly improve the dispersion viscosity, which is crucial for extending the sweep range and enhancing oil recovery. Recently, graphene oxide (GO) nanosheets have attracted extensive attention due to their high chemical reactivity and specific surface. In this paper, the AA molecule, synthesized by acrylamide (AM) and 2-acrylamido-2-methypropanesulfonic acid (AMPS) copolymerization, modified GO nanosheets (GAA) material is firstly synthesized and characterized. With the same content of AMPS segments, GAAn systems consistently exhibit better dispersion stability than AAn systems, along with higher absolute zeta potential values. The comprehensive investigation on the rheological property of GAA system reveals that GAA15 with the highest AMPS content exhibits the largest zero-shear viscosity (409.27 mPa·s) and the longest relaxation time. Based on the molecular dynamic simulation approaches, the aggregation morphology and stability of AA and GAA molecules are evaluated via the configuration analysis and the statistics of hydrogen bond numbers. The abundant binding sites from GO segments of GAA promote additional hydrogen bonds between GAA molecules and water, resulting in a more stable configuration. Molecular surface potential analysis and the independent gradient model based on Hirshfeld partition (IGMH) methods are further used to visualize the non-bonded interaction existed in cross-linked networks, which also predict and validate non-bonding interaction sites among molecular segments. The simulation results indicate higher viscosity in the GAA system should be ascribed to the formation of dispersion-strengthened cross-linked structures (AM-GO plane and GO-GO stacking segments). In summary, the microscopic viscosity-increasing mechanism of novel GAA system is proposed from the perspective of intermolecular interactions, which lays a preliminary theoretical foundation for the application of GAA material in the oil industry.

Orb2 enables rare-codon-enriched mRNA expression during Drosophila neuron differentiation

Regulation of codon optimality is an increasingly appreciated layer of cell- and tissue-specific protein expression control. Here, we use codon-modified reporters to show that differentiation of Drosophila neural stem cells into neurons enables protein expression from rare-codon-enriched genes. From a candidate screen, we identify the cytoplasmic polyadenylation element binding (CPEB) protein Orb2 as a positive regulator of rare-codon-dependent mRNA stability in neurons. Using RNA sequencing, we reveal that Orb2-upregulated mRNAs in the brain with abundant Orb2 binding sites have a rare-codon bias. From these Orb2-regulated mRNAs, we demonstrate that rare-codon enrichment is important for mRNA stability and social behavior function of the metabotropic glutamate receptor (mGluR). Our findings reveal a molecular mechanism by which neural stem cell differentiation shifts genetic code regulation to enable critical mRNA stability and protein expression.

Thiol-yne click post-synthesis of phenylboronic acid-functionalized magnetic cyclodextrin microporous organic network for selective and efficient extraction of antiepileptic drugs

Owing to their incomplete digestion in the human body and inadequate removal by sewage treatment plants, antiepileptic drugs (AEDs) accumulate in water bodies, potentially affecting the exposed humans and aquatic organisms. Therefore, sensitive and reliable detection methods must be urgently developed for monitoring trace AEDs in environmental water samples. Herein, a novel phenylboronic acid-functionalized magnetic cyclodextrin microporous organic network (Fe3O4@CD-MON-PBA) was designed and synthesized via the thiol-yne click post-modification strategy for selective and efficient magnetic solid-phase extraction (MSPE) of trace AEDs from complex sample matrices through the specific B–N coordination, π-π, hydrogen bonding, electrostatic, and host-guest interactions. Fe3O4@CD-MON-PBA exhibited a large surface area (118.5 m2 g−1), rapid magnetic responsiveness (38.6 emu g−1, 15 s), good stability and reusability (at least 8 times), and abundant binding sites for AEDs. Under optimal extraction conditions, the proposed Fe3O4@CD-MON-PBA-MSPE-HPLC-UV method exhibited a wide linear range (0.5–1000 μg L−1), low limits of detection (0.1–0.5 μg L−1) and quantitation (0.3–2 μg L−1), good anti-interference ability, and large enrichment factors (92.2–104.3 to 92.3–98.0) for four typical AEDs. This work confirmed the feasibility of the thiol-yne click post-synthesis strategy for constructing novel and efficient multifunctional magnetic CD-MONs for sample pretreatment and elucidated the significance of B–N coordination between PBA and N-containing AEDs.

Deciphering the role of extracellular polymeric substances in the adsorption and biotransformation of organic micropollutants during anaerobic wastewater treatment

Extracellular polymeric substances (EPS) participate in the removal of organic micropollutants (OMPs), but the primary pathways of removal and detailed mechanisms remain elusive. We evaluated the effect of EPS on removal for 16 distinct chemical classes of OMPs during anaerobic digestion (AD). The results showed that hydrophobic OMPs (HBOMPs) could not be removed by EPS, while hydrophilic OMPs (HLOMPs) were amenable to removal via adsorption and biotransformation of EPS. The adsorption and biotransformation of HLOMPs by EPS accounted up to 19.4 ± 0.9 % and 6.0 ± 0.8 % of total removal, respectively. Further investigations into the adsorption and biotransformation mechanisms of HLOMPs by EPS were conducted utilizing spectral, molecular dynamics simulation, and electrochemical analysis. The results suggested that EPS provided abundant binding sites for the adsorption of HLOMPs. The binding of HLOMPs to tryptophan-like proteins in EPS formed nonfluorescent complexes. Hydrogen bonds, hydrophobic interactions and water bridges were key to the binding processes and helped stabilize the complexes. The biotransformation of HLOMPs by EPS may be attributed to the presence of extracellular redox active components (c-type cytochromes (c-Cyts), c-Cyts-bound flavins). This study enhanced the comprehension for the role of EPS on the OMPs removal in anaerobic wastewater treatment.

Silica Nanowires-Filled Glass Microporous Sensor for the Ultrasensitive Detection of Deoxyribonucleic Acid.

DNA carries genetic information and can serve as an important biomarker for the early diagnosis and assessment of the disease prognosis. Here, we propose a bottom-up assembly method for a silica nanowire-filled glass microporous (SiNWs@GMP) sensor and develop a universal sensing platform for the ultrasensitive and specific detection of DNA. The three-dimensional network structure formed by SiNWs provides them with highly abundant and accessible binding sites, allowing for the immobilization of a large amount of capture probe DNA, thereby enabling more target DNA to hybridize with the capture probe DNA to improve detection performance. Therefore, the SiNWs@GMP sensor achieves ultrasensitive detection of target DNA. In the detection range of 1 aM to 100 fM, there is a good linear relationship between the decrease rate of current signal and the concentration of target DNA, and the detection limit is as low as 1 aM. The developed SiNWs@GMP sensor can distinguish target DNA sequences that are 1-, 3-, and 5-mismatched, and specifically recognize target DNA from complex mixed solution. Furthermore, based on this excellent selectivity and specificity, we validate the universality of this sensing strategy by detecting DNA (H1N1 and H5N1) sequences associated with the avian influenza virus. By replacing the types of nucleic acid aptamers, it is expected to achieve a wide range and low detection limit sensitive detection of various biological molecules. The results indicate that the developed universal sensing platform has ultrahigh sensitivity, excellent selectivity, stability, and acceptable reproducibility, demonstrating its potential application in DNA bioanalysis.

Waste treats waste: Facile fabrication of porous adsorbents from recycled PET and sodium alginate for efficient dye removal

Dye-contaminated water and waste plastic both pose enormous threats to human health and the ecological environment, and simultaneously solving these two issues in a sustainable and resource-saving way is highly important. In this work, a sodium alginate-polyethylene terephthalate-sodium alginate (SA@PET) composite adsorbent for efficient dye removal is fabricated using wasted PET bottle and marine plant-based SA via simple and energy-efficient nonsolvent-induced phase separation (NIPS) method. Benefiting from its porous structure and the abundant binding sites, SA@PET shows an excellent methylene blue (MB) adsorption capacity of 1081 mg g−1. The Redlich–Peterson model more accurately describes the adsorption behavior, suggesting multiple adsorption mechanisms. In addition to the electrostatic attractions of SA to MB, polar interactions between the PET matrix and MB are also identified as adsorption mechanisms. It is worth mentioning that SA@PET could be recycled 7 times without a serious decrease in performance, and the trifluoroacetic acid-dichloromethane solvent involved in the NIPS process has the possibility of reuse and stepwise recovery. Finally, the discarded adsorbent could be completely degraded under mild conditions. This work provides not only a composite adsorbent with excellent cationic dye removal performance for wastewater treatment, but also an upcycling strategy for waste PET.

A novel electrochemical immunosensor for sensitive detection of depression marker Apo-A4 based on bipyridine-functionalized covalent organic frameworks.

Anovel electrochemical immunosensor for detecting potential depression biomarker Apolipoprotein A4 (Apo-A4) was developed using a multi-signal amplification approach. Firstly, the sensor utilized a modified electrode material, NG-PEI-COF, combining bipyridine-functionalized covalent organic framework (COF) and polyethyleneimine-functionalized nitrogen-doped graphene (NG-PEI), providing high surface area and excellent electron transfer capability for the first-stage amplification in electrical signal conduction. Subsequently, gold nanoparticles (AuNPs) were further electrodeposited onto the electrode, providing good biocompatibility and abundant binding sites for immobilizing the target antigen, thus achieving the second-stage amplification in target recognition and binding. To address the lack of redox properties of the antigen, a tracer probe was formed by loading AuNPs, anti-Apo-A4, and toluidine blue (TB) successively onto COF, leading to the third-stage amplification in signal conversion. The constructed electrochemical immunosensor TB/Ab/AuNPs/COF-Apo-A4/AuNPs/NG-PEI-COF/GCE exhibited excellent detection performance against Apo-A4 with a linear range of 0.01 to 300 ng mL-1 and had a low detection limit of 2.16 pg mL-1 (S/N = 3). In addition, the biosensor had good reproducibility (RSD = 2.31%), stability, and significant anti-interference performance toward other depression biomarkers. The sensor hasbeen successfully used for the quantitative detection of Apo-A4 in serum, providing potential applications for detecting Apo-A4 in the clinic and serving as a reference for constructing sensing methods based on COF.

Freestanding Nanofiber-Assembled Aptasensor for Precisely and Ultrafast Electrochemical Detection of Alzheimer's Disease Biomarkers.

Amyloid beta-protein (AβAβ) is a main hallmark of Alzheimer's disease (AD), and a low amount of Aβ protein accumulation appears to be a potential marker for AD. Here, an electrochemical DNA biosensor based on polyamide/polyaniline carbon nanotubes (PA/PANI-CNTs) is developed with the aim of diagnosing AD early using a simple, low-cost, and accessible method to rapidly detect Aβ42 in human blood. Electrospun PA nanofibers served as the skeleton for the successive in situ deposition of PANI and CNTs, which contribute both high conductivity and abundant binding sites for the Aβ42 aptamers. After the aptamers are immobilized, this aptasensor exhibits precise and specific detection of Aβ42 in human blood within only 4min with an extremely fast response rate, lower detection limit, and excellent linear detection range. These findings make a significant contribution to advancing the development of serum-based detection techniques for Aβ42, thereby paving the way for improved diagnostic capabilities in the field of AD.

Support Platform of Functionalized Sustainable Cellulose Self-Entanglement Monolithic Adsorbents for Efficient Adsorption of Cadmium(II) Ions.

Serious water contamination induced by massive discharge of cadmium(II) ions is becoming an emergent environmental issue due to high toxicity and bioaccumulation; thus, it is extremely urgent to develop functional materials for effectively treating with Cd2+ from wastewater. Benefiting from abundant binding sites, simple preparation process, and adjustable structure, UiO-66-type metal-organic frameworks (MOFs) had emerged as promising candidates in heavy metal adsorption. Herein, monolithic UiO-66-(COOH)2-functionalized cellulose fiber (UCLF) adsorbents were simply fabricated by incorporating MOFs into cellulose membranes through physical blending and self-entanglement. A two-dimensional structure was facilely constructed by cellulose fibers from sustainable biomass agricultural waste, providing a support platform for the integration of eco-friendly UiO-66-(COOH)2 synthesized with lower temperature and toxicity solvent. Structure characterization and bath experiments were performed to determine operational conditions for the maximization of adsorption capacity, thereby bringing out an excellent adsorption capacity of 96.10 mg/g. UCLF adsorbent holding 10 wt % loadings of UiO-66-(COOH)2 (UCLF-2) exhibited higher adsorption capacity toward Cd2+ as compared to other related adsorbents. Based on kinetics, isotherms, and thermodynamics, the adsorption behavior was spontaneous, exothermic, as well as monolayer chemisorption. Coordination and electrostatic attraction were perhaps mechanisms involved in the adsorption process, deeply unveiled by the effects of adsorbate solution pH and X-ray photoelectron spectroscopy. Moreover, UCLF-2 adsorbent with good mechanical strength offered a structural guarantee for the successful implementation of practical applications. This study manifested the feasibility of UCLF adsorbents used for Cd2+ adsorption and unveiled a novel strategy to shape MOF materials for wastewater decontamination.

Colloidal photonic crystals towards biological applications.

Colloidal photonic crystals (CPCs), fabricated from the assembly of micro-/nano-particles, have attracted considerable interest due to their unique properties, such as structural color, slow-photon effect, and high specific surface area (SSA). Benefiting from these properties, significant progress has been made in the biological applications of CPCs. In this perspective, these properties and relative manipulation strategies are firstly discussed, building bridges between properties and biological applications of CPCs. Structural color endows CPCs with naked-eye sensing capability, which can be applied to physiological state assessment and diagnosis, as well as self-report of CPC-based diagnostic and therapeutic devices. The slow-photon effect contributes to enhanced fluorescence, surface-enhanced Raman scattering, and efficacy of photodynamic/photothermal therapy, when CPCs are combined with corresponding functional materials. High SSA provides CPCs with abundant binding sites and superior capabilities for loading, adsorption, delivery, etc. These properties can be utilized individually or synergistically to grant CPCs superior performance in biological applications. Next, the recent advancements of CPCs towards biological applications are summarized, including biosensors, wound dressings, cells-on-a-chip, and phototherapy. Finally, a perspective on the challenges and future development of CPCs for biological applications is presented.

A lipase-conjugated carbon nanotube fiber-optic SPR sensor for sensitive and specific detection of tributyrin.

As a low-density lipoprotein, tributyrin plays an essential role in food safety and human health. In this study, a novel lipase-conjugated carbon nanotube (CNT) surface plasmon resonance (SPR) fiber-optic sensor is used to specifically detect tributyrin for the first time. In this work, CNTs can be used as an amplifying material to significantly increase the sensitivity of SPR sensors due to their high refractive index and large surface area. CNTs can also be used as an enzyme carrier to provide abundant carboxyl groups for the specific binding of lipases. Covering the surface of the sensor with CNTs can not only enhance the performance of the sensor, but also provide sufficient detection sites for subsequent biomass detection, reduce the functionalization steps, and simplify the sensor preparation process. The experimental results demonstrate that the refractive index sensitivity of the traditional multimode fiber (MMF)-single mode fiber (SMF)-MMF transmissive optical fiber sensor is 1705 nm RIU-1. After covering the sensor with CNTs, the sensitivity is 2077 nm RIU-1, and the sensitivity has been improved very well. In addition, there are abundant functional groups on CNTs, which can provide abundant binding sites. Conjugating lipase on carbon nanotubes helps to achieve linear detection in the range of 0.5 mM to 4 mM tributyrin, with a sensitivity of 4.45 nm mM-1 and a detection limit of 0.34 mM, which is below the 2.26 mM detection standard and meets food safety monitoring requirements. Compared with other sensors, the optical fiber biosensor proposed in this study expands the concentration detection range of tributyrin. Furthermore, the sensor also has good stability, anti-interference performance and specificity. Therefore, the sensor proposed in this paper has good application prospects in the fields of food safety and biomedicine.

A sensitive immunosensor for the detection of alkaline phosphatase as a biomarker for fracture healing

Fractures occur at all ages and are highly prevalent. At the same time, there is a problem of delayed healing after fracture, and drugs are often taken to promote healing. Alkaline phosphatase (ALP) is an important indicator for assessing fracture healing, and achieving its quantification would be helpful in evaluating fracture recovery in patients on medication. Here, we present an ultrasensitive immunosensor based on NH2-MIL-101(Cr)@AuNPs/rGO nanocomposites. The poor conductivity of metal–organic skeletons (MOF) limits their electrochemical applications. In this study, NH2-MIL-101(Cr) was used as a carrier for the in situ reductive growth of gold nanoparticles (AuNPs) on its surface. Then NH2-MIL-101(Cr)@AuNPs were synergized with reduced graphene oxide (rGO) to amplify the electrochemical signals. The obtained NH2-MIL-101(Cr)@AuNPs/rGO nanocomposites exhibited electrical conductivity and stability. Mercaptosuccinic acid introduces a sufficiently large number of carboxyl groups by binding to AuNPs, providing abundant binding sites for ALP antibodies. The immunosensor used differential pulse voltammetry (DPV) for electrochemical analysis, and could capture the concentration response in the range of 10-12 −10-5 g mL−1 with a relatively low detection limit of 1.64 pg mL−1. In addition, the sensor has been successfully applied to the detection of ALP in massively diluted serum of fracture patients before and after drug administration.