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A multifactorial mechanism for successful dissolution of polymeric carbon nitrides (pCN) was disclosed, enabling pCN to compound more advanced nanocomposites at the molecular level, beyond the traditional solar fuel applications in powders.

Self-adaptability is highly envisioned for artificial devices such as robots with chemical noses. For this goal, seeking catalysts with multiple and modulable reaction pathways is promising but generally hampered by inconsistent reaction conditions and negative internal interferences. Herein, we report an adaptable graphitic C6N6-based copper single-atom catalyst. It drives the basic oxidation of peroxidase substrates by a bound copper-oxo pathway, and undertakes a second gain reaction triggered by light via a free hydroxyl radical pathway. Such multiformity of reactive oxygen-related intermediates for the same oxidation reaction makes the reaction conditions capable to be the same. Moreover, the unique topological structure of CuSAC6N6 along with the specialized donor-π-acceptor linker promotes intramolecular charge separation and migration, thus inhibiting negative interferences of the above two reaction pathways. As a result, a sound basic activity and a superb gain of up to 3.6 times under household lights are observed, superior to that of the controls, including peroxidase-like catalysts, photocatalysts, or their mixtures. CuSAC6N6 is further applied to a glucose biosensor, which can intelligently switch sensitivity and linear detection range in vitro.

Facile evaluation of oxygen reduction reaction (ORR) kinetics for massive electrocatalysts is critical for sustainable fuel cells development and industrial H2O2 production. Despite great success in ORR studies by mainstream strategies, such as membrane electrode assembly, rotation electrode technique and advanced surface-sensitive spectroscopy, the time/spatial distribution of reactive oxygen species (ROS) intermediates in the diffusion layer is still unknown. By time-dependent electrochemiluminescence (Td-ECL), here we report an intermediate-oriented methodology for ORR kinetics analysis. Thanks to multiple ultra-sensitive stoichiometric reactions between ROS and the ECL emitter, except for electron transfer numbers and rate constants, the potential-dependent time/spatial distribution of ROS was successfully obtained for the first time. Such uncovered exclusive information would guide fuel cells and H2O2 production with maximized activity and durability, for instance, a larger overpotential would be beneficial to electrocatalysts of 2e reduction for H2O2 production, because of the high yield of H2O2 and low concentration of attackable O2•. This work would pave the exploration of not only the fundamentals of unambiguous ORR mechanism but also the durability of electrocatalysts for practical applications.

Stimuli-responsive metal-organic framework nanoparticles, NMOFs, provide a versatile platform for the controlled release of drugs and biomedical applications. The porous structure of NMOFs, their biocompatibility, low toxicity, and efficient permeability turn the NMOFs into ideal carriers for therapeutic applications. Two general methods to gate the drug-loaded NMOFs and to release the loads were developed: by one method, the loaded NMOFs are coated or surface-modified with stimuli-responsive gates being unlocked in the presence of appropriate chemical (e.g., ions or reducing agents), physical (e.g., light or heat), or biomarker (e.g., miRNA or ATP) triggers. By a second approach, the drug-loaded NMOFs include encoded structural information or co-added agents to induce the structural distortion or stimulate the degradation of the NMOFs. Different chemical triggers such as pH changes, ions, ATP, or redox agents, and physical stimuli such as light or heat are applied to degrade the NMOFs, resulting in the release of the loads. In addition, enzymes, DNAzymes, and disease-specific biomarkers are used to unlock the gated NMOFs. The triggered release of drugs for cancer therapy, anti-blood clotting, and the design of autonomous insulin-delivery systems ("artificial pancreas") are discussed. Specifically, multi-drug carrier systems and functional NMOFs exhibiting dual and cooperative therapeutic functions are introduced. The future perspectives and applications of stimuli-responsive particles are addressed.

The emergence of nucleic acid-based constitutional dynamic networks, CDNs, from a pool of nucleic acids is a key process for the understanding and modality of the evolution of biological networks. We present a versatile method that applies a library of nucleic acids coupled to biocatalytic DNA machineries as functional modules for the emergence of CDNs of diverse composition, complexity, and structural diversity. A set of four DNA template/blocker scaffolds coupled to the polymerase/dNTP replication machinery leads, in the presence of a primer, P1, to the gated replication of the scaffolds and to the displacement of four components that reconfigure into a [2 × 2] CDN. Using six template/blocker scaffolds and the polymerase/dNTPs, the P1-guided emergence of a [3 × 3] CDN is demonstrated. In addition, by further engineering the template/blocker scaffolds, the hierarchical control over the composition of the P1-guided emergence of [3 × 3] CDNs is accomplished. Also, sequence-engineered template/blocker scaffolds, coupled to the polymerase/dNTP machinery, lead, in the presence of two primers P1 and/or P2, to the selective emergence of two different [2 × 2] CDNs or to a [3 × 3] CDN. Also, a set of six appropriately engineered template/blocker scaffolds, coupled to the polymerase/dNTP machinery, leads to the emergence of a CDN composed of four equilibrated DNA tetrahedra constituents. Finally, by further sequence engineering of the set of template/blocker scaffolds and their coupling to a nicking/polymerization/dNTP replication machinery, the amplified high-throughput emergence of CDNs is demonstrated.

Inspired by nature where intracellular dynamic interactions between DNA, RNA and proteins processed within complex networks leading to programmed reaction patterns, extensive research efforts are directed to mimic these processes by chemical means, "Systems Chemistry". The present perspective introduces nucleic acids as functional modules to construct constitutional dynamic networks, CDNs, mimicking natural networks. The base sequences comprising nucleic acids provide a rich "tool box" to assemble signal-triggered reconfigurable CDNs revealing adaptive and hierarchically adaptive properties, intercommunication between CDNs, and feedback-driven reaction pathways similar to natural systems. Pathways for the evolution of CDNs and the formation of networks of enhanced complexities are discussed. Different applications of constitutional dynamic networks are introduced including programmed catalysis, CDN-guided optical and catalytic functions of nanoparticle aggregates, and CDN-dictated stiffness and self-healing functions of hydrogels. Future perspectives of the field in designing dissipative transient CDNs, CDNs-guided transcription/translation synthesis of selective proteins, and the challenging integration of CDNs into cell-like containments aiming to assemble "artificial cells" are addressed.

Gated dissipative artificial photosynthetic systems modeling dynamically modulated environmental effects on the photosynthetic apparatus are presented. Two photochemical systems composed of a supramolecular duplex scaffold, a photosensitizer-functionalized strand (photosensitizer is Zn(II)protoporphyrin IX, Zn(II)PPIX, or pyrene), an electron acceptor bipyridinium (V2+)-modified strand, and a nicking enzyme (Nt.BbvCI) act as functional assemblies driving transient photosynthetic-like processes. In the presence of a fuel strand, the transient electron transfer quenching of the photosensitizers, in each of the photochemical systems, is activated. In the presence of a sacrificial electron donor (mercaptoethanol) and continuous irradiation, the resulting electron transfer process in the Zn(II)PPIX/V2+ photochemical module leads to the transient accumulation and depletion of the bipyridinium radical-cation (V·+) product, and in the presence of ferredoxin-NADP+ reductase and NADP+, to the kinetically modulated photosynthesis of NADPH. By subjecting the mixture of two photochemical modules to one of two inhibitors, the gated transient photoinduced electron transfer in the two modules is demonstrated. Such gated dissipative process highlights its potential as an important pathway to protect artificial photosynthetic module against overdose of irradiance and to minimize photodamage.

The broadband C3N4 semiconductor absorbs in the UV region, λ = 330-380 nm, a feature limiting its application for light-to-energy conversion. The unique surface adsorption properties of C3N4 allow, however, the binding of a photosensitizer, operating in the visible-solar spectrum to the surface of C3N4. Coupling of the energy levels of the photosensitizer with the energy levels of C3N4 allows effective photoinduced electron-transfer quenching and subsequent charge separation in the hybrid structures. Two methods to adsorb a photosensitizer on the C3N4 nanoparticles are described. One is exemplified by the adsorption of Zn(II)-protoporphyrin IX on C3N4 using π-π interactions. The second method utilizes the specific binding interactions of single-stranded nucleic acids on C3N4 and involves the binding of a Ru(II)-tris-bipyridine-modified nucleic acid on the C3N4 nanoparticles. Effective electron-transfer quenching of the photoexcited photosensitizers by C3N4 proceeds in the two hybrid systems. The two hybrid photosystems induce the effective photosensitized reduction of N,N'-dimethyl-4,4'-bipyridinium, MV2+, to MV+•, in the presence of Na2EDTA as a sacrificial electron donor. The generation of MV+• is ca. 5-fold higher as compared to the formation of MV+• in the presence of the photosensitizer alone (in the absence of C3N4). The effective generation of MV+• in the photosystems is attributed to the efficient quenching of the photosensitizers, followed by effective charge separation of the electrons in the conduction band of C3N4 and the holes in the oxidized photosensitizer. The subsequent transfer of the conduction-band electrons to MV2+ and the oxidation of Na2EDTA by the oxidized photosensitizers lead to the effective formation of MV+•. The photogenerated MV+• by the two hybrid photosystems is used to catalyze H2 evolution in the presence of Pt nanoparticle catalysts and to mediate the reduction of NADP+ to NADPH, in the presence of ferredoxin-NADP+ reductase, FNR. The ability to couple the photogenerated NADPH to drive NADP+-dependent biocatalytic transformations is demonstrated.

The efficient and low-cost platinum group metal (PGM)-free metal-nitrogen-carbon electrocatalysts (M-N-C) are potential alternatives for the oxygen reduction reaction (ORR) in artificial energy conversion devices. However, the solid-state reactions of M/C/N-containing precursors at high temperature was rather complicated, making the engineering of carbonization processes of M-N-C catalysts challenging and less explored. Herein, we report a way to modulate the pyrolysis processes of M-N-C by pre-organization of the molecular precursors via a simple solvation, in which, the simultaneous hydrogen bonding and coordination interactions played an important roles. It was revealed that the supramolecular precursors from different solvents had the same chemical compositions but quite different crystal structures. Accordingly, the pyrolysis processes were greatly altered, making the as-prepared Co-N-C exhibit distinct morphologies ranging from worm-nanotubes to bamboo-nanotubes and to porous nanosheets. The optimized Co-N-C showed competitive bifunctional electrocatalytic ORR and OER activities, which were further successfully applied to advance the rechargeable Zn–air batteries with excellent cycling stability over 600 h at a current density of 20 mA cm−2 and voltage gap (0.76 V). This work highlights the great potential of the pre-organization for the designing and selecting of precursors to engineer pyrolyzed M-N-C with higher electrocatalytic activities.

The assembly of reversible stimuli-responsive locked DNA origami tiles being unlocked, in the presence of appropriate triggers, to form nanocavities in the origami rafts, is introduced. In the presence of ATP, K+-ion-stabilized G-quadruplexes or pH-responsive T-A·T triggers and appropriately engineered “helper units”, the origami rafts are unlocked to form nanocavities. By the application of appropriate counter-triggers, the nanocavities are relocked, thus establishing the switchable and reversible “mechanical” opening and closure mechanism of the nanocavities. The interconnection of the stimuli-responsive origami tiles into dimer structures enables the programmed triggered unlocking of each of the origami tiles, or both of the origami tiles, to yield dictated nanocavity-containing tiles. In addition, the functionalization of the opposite faces of the origami tiles with Mg2+-ion-dependent DNAzyme subunits leads, upon the triggered unlocking of the nanocavities, to the self-assembly of the active DNAzymes in the confined cavities. By the cyclic opening and closure of the cavities the reversible “ON”/“OFF” activation of the Mg2+-ion-dependent DNAzyme is demonstrated. Furthermore, upon the tethering of different Mg2+-ion-dependent subunits to the opposite faces of stimuli-responsive dimer origami tiles, the triggered programmed catalytic operation of different Mg2+-ion-dependent DNAzymes in the confined nanocavities, associated with the origami tiles, is demonstrated., Programmed unlocking of nanocavities in origami dimer structures using different auxiliary triggers.

A nucleic acid-based constitutional dynamic network (CDN) is introduced as a single computational module that, in the presence of different sets of inputs, operates a variety of logic gates including a half adder, 2 : 1 multiplexer and 1 : 2 demultiplexer, a ternary multiplication matrix and a cascaded logic circuit. The CDN-based computational module leads to four logically equivalent outputs for each of the logic operations. Beyond the significance of the four logically equivalent outputs in establishing reliable and robust readout signals of the computational module, each of the outputs may be fanned out, in the presence of different inputs, to a set of different logic circuits. In addition, the ability to intercommunicate constitutional dynamic networks (CDNs) and to construct DNA-based CDNs of higher complexity provides versatile means to design computing circuits of enhanced complexity., A nucleic acid-based constitutional dynamic network (CDN) provides a single functional computational module for diverse input-guided logic operations and computing circuits.

Understanding the spatiotemporal effects of surface topographies and modulated stiffness and anisotropic stresses of hydrogels on cell growth remains a biophysical challenge. Here we introduce the photolithographic patterning or two-photon laser scanning confocal microscopy patterning of a series of o-nitrobenzylphosphate ester nucleic acid-based polyacrylamide hydrogel films generating periodically-spaced circular patterned domains surrounded by continuous hydrogel matrices. The patterning processes lead to guided modulated stiffness differences between the patterned domains and the surrounding hydrogel matrices, and to the selective functionalization of sub-regions of the films with nucleic acid anchoring tethers. HeLa cells are deposited on the circularly-shaped domains functionalized with the MUC-1 aptamers. Initiation of the hybridization chain reaction by nucleic acid tethers associated with the continuous hydrogel matrix results in stress-induced ordered orthogonal shape-changes on the patterned domains, leading to ordered shapes of cell aggregates bound to the patterns., Spatiotemporal patterning of hydrogel matrices has been used to control cell behavior. Here the authors present photoresponsive DNA-based hydrogels and demonstrate patterning of physical and biochemical properties to tune local cell responses.

Nucleic acid based, out-of-equilibrium, dissipative networks driven by nucleic acid fuels coupled to the nicking enzyme, Nt.BbvCI, are presented. One set of experiments includes a functional module consisting of a duplex and two fluorophore-labeled strands. The fuel-triggered activation of the functional module leads to a supramolecular intermediate composed of a template bound to the two fluorophore-labeled strands. Nicking of the fuel strand by Nt.BbvCI yields "waste" products, resulting in the regeneration of original system. The transient dissipative behavior of the systems is probed by following the FRET signal generated by the fluorophore labels associated with the intermediate supramolecular complex. The second set of experiments introduces two functional modules activated in parallel by the fuel strand. Using two inhibitors, I1 or I2, the selective gated dissipative operation of the networks is demonstrated. Finally, experiments presenting the intercommunication and cascading of two dissipative networks are introduced. Subjecting the networks to the fuel strands leads to intercommunication between the networks by strand-transfer and strand-feedback processes, allowing the cascaded dissipative operation of the assembly. The experimental results of the different dissipative systems are accompanied by kinetic models and computational simulations. The computational simulations provide useful means to predict the dissipative transient patterns of the systems at different auxiliary conditions.

Due to great potential in nanobiotechnology, nanomachines, and smart materials, DNA-directed disassembly of gold nanoparticles (AuNPs) has been extensively explored. In a typical system, nonbase-paired regions (e.g., overhangs and gaps in the linker DNA and oligonucleotide spacers between thiol group and hybridization sequence) are indispensable portions in the disassembly of AuNPs based on DNA displacement reaction. Therefore, it is necessary to study the effect of nonbase-paired regions to improve the kinetics of disassembly of AuNPs. Herein, the disassembly rate of AuNPs based on DNA displacement reaction was investigated by using different length spacers and linker DNA containing various lengths of gaps or overhangs. Interestingly, it was revealed that among the gaps in the linker DNA could be most effectively used to improve the disassembly rate of the AuNPs. As a result, when we introduced gaps into linker DNA, the DNA displacement reaction of AuNPs was markedly shortened to less than 50 min, which was much faster than the previous methods. As a proof of the importance of our findings, a rapid AuNP-based colorimetric DNA biosensor has been successfully prepared. In addition, we showed that the signal of the biosensors could be further amplified using exonuclease III, resulting in a much lower detection limit in comparison with previous sensors similarly using AuNP aggregates as probes.

A NIR light activatable membrane fusion method was developed for cancer cell therapeutic applications., The spatiotemporal stimulation of liposome–liposome or liposome–membrane fusion processes attracts growing interest as a means to mimic cell–cell interactions in nature and for using these processes for biomedical applications. We report the use of o-nitrobenzyl phosphate functionalized-cholesterol tethered nucleic acid-modified liposomes as functional photoresponsive units for inducing, by NIR-irradiation, spatiotemporal liposome–liposome or liposome–membrane fusion processes. The liposomes are loaded with upconversion nanoparticles (UCNPs) and their NIR irradiation (λ = 980 nm) yields luminescence at λ = 365 nm, providing a localized light-source to deprotect the o-nitrobenzyl phosphate groups and resulting in the fragmentation of the nucleic acid structures. In one system, the NIR-triggered fusion of two liposomes, L1 and L2, is exemplified. Liposome L1 is loaded with UCNPs and Tb3+ ions, and the liposome boundary is functionalized with a cholesterol-tethered, o-nitrobenzyl phosphate caged hairpin nucleic acid structure. Liposome L2 is loaded with 2,6-pyridinedicarboxylic acid, DPA, and its boundary is modified with a cholesterol-tethered nucleic acid, complementary to a part of the caged hairpin, associated with L1. NIR-irradiation of the L1/L2 mixture resulted in the photocleavage of the hairpin structure, associated with L1, and the resulting fragmented nucleic acid associated with L1 hybridized with the nucleic acid linked to L2, leading to the fusion of the two liposomes. The fusion process was followed by dynamic light scattering, and by monitoring the fluorescence of the Tb3+–DPA complex generated upon the fusion of the liposomes and their exchange of contents (fusion efficiency 30%). In a second system, the fusion of the liposomes L1, loaded with UCNPs and doxorubicin (DOX), with HeLa cancer cells functionalized with nucleic acid tethers, complementary to the hairpin units associated with the boundary of L1, and linked to the MUC-1 receptor sites associated with the HeLa cells, through a MUC-1 aptamer unit is exemplified. The effect of DOX-loaded L1/HeLa cell fusion on the cytotoxicity towards HeLa cells is addressed. The NIR UCNP-stimulated cleavage of the o-nitrobenzyl phosphate caged hairpin units associated with L1 leads to the fragmentation of the hairpin units and the resulting nucleic acid tethers hybridize with the nucleic acid-modified HeLa cells, resulting in the liposome–HeLa cell fusion and the release of DOX into the HeLa cells. Selective spatiotemporal cytotoxicity towards HeLa cells is demonstrated (ca. 40% cell killing within two days). The study presents a comprehensive stepwise set of experiments directed towards the development of NIR-driven liposome–liposome or liposome–membrane fusion processes.

The information encoded in the base sequences of nucleic acids is used to construct [3 × 2] or [3 × 3] constitutional dynamic networks (CDNs) composed of six or nine constituents, respectively. In the presence of appropriate triggers, the adaptive and hierarchical reconfiguration of the CDNs is demonstrated. The reconfiguration of the CDNs, which involves the triggered stabilization and upregulation of a specific constituent is accompanied by the upregulation of the constituents that do not share component connectivities with the trigger-stabilized constituent, and by the concomitant downregulation of the constituents sharing component connectivities with the trigger-stabilized constituent. Using a set of different triggers, a series of reconfigured networks-in-networks are demonstrated. The operation and reconfiguration of the CDNs are based on the following motives: (i) Each of the constituents in the [3 × 2] or [3 × 3] CDNs is composed of a supramolecular structure consisting of two duplex-bridged double-loop quasi-circle units. The hybridization of a single-stranded trigger with the double-loop domain stabilizes the respective constituent, and this results in the reconfiguration of the CDNs. (ii) To each of the constituents is conjugated a Mg

The switchable reconfiguration of a mixture of two dimers of DNA origami tiles, AB and CD, into a mixture of two DNA origami dimers composed of AD and CB, using a collection of fuel and antifuel strands, is presented. The reversible reconfiguration of the mixture of dimers AB and CD into AD and CB, is followed by labeling each of the tiles with 0, 1, 2, and 3 4× hairpins labels and by imaging the dimer structures by atomic force microscopy. Subjecting the reconfigurable dimer mixtures to a collection of Mg2+-ion-dependent DNAzyme subunits and the substrates consisting of the ROX/BHQ2-modified substrate and the FAM/BHQ1-modified substrate leads to the triggered and programmed switchable operation, in the presence of appropriate fuel and antifuel strands. In the presence of the AB and CD mixture, the DNAzyme subunits cleaving the ROX/BHQ2-modified substrate is switched on, leading to the fluorescence of ROX. The reconfiguration of the AB and CD dimer mixture to the AD and CB dimer mixture leads to the assem...

Constitutional dynamic networks (CDNs) consisting of DNA tetrahedra allow the dynamically triggered adaptive control over the compositions and structures of the constituents. In one system, a CDN consisting of four tetrahedra constituents is orthogonally triggered by two alternative triggers, T1 or T2, to reconfigure into two different CDNs, revealing adaptive control-over the tetrahedra compositions in the two CDNs. In the presence of the counter triggers T1' or T2', the parent CDN is regenerated. In the second system, the assembly of a CDN consisting of four dimeric tetrahedra exhibiting variable sizes and shapes is described. The orthogonal triggering of the CDN by two different triggers T3 or T4, leads to the adaptive reconfiguration of the CDN into new equilibrated CDNs exhibiting control-over the compositions and shapes of the dimeric tetrahedra comprising the CDNs. Mg2+-ion-dependent DNAzyme units conjugated to the tetrahedra nanostructures and complementary electrophoretic experiments provide means to quantitatively evaluate the compositions of the different CDN systems. By the functionalization of the four-tetrahedra-based CDN system with two fluorophor donor-acceptor pairs and the orthogonal reconfiguration of the CDN in the presence of two alternative triggers, the control-over the FRET functions of the CDN systems is demonstrated.

The reversible and switchable triggered reconfiguration of tetrahedra nanostructures from monomer tetrahedra structures into dimer or trimer structures is introduced. The triggered bridging of monomer tetrahedra by K+ -ion-stabilized G-quadruplexes or T-A•T triplexes leads to dimer or trimer tetrahedra structures that are separated by crown ether or basic pH conditions, respectively. The signal-triggered dimerization/trimerization of DNA tetrahedra structures is used to develop multiplexed miRNA-sensing platforms, and the tetrahedra mixture is used for intracellular sensing and imaging of miRNAs.

Here, we present a facile approach to synthesizing nitrogen-doped porous carbon materials (NPCs) through carbonization of poly(o-phenylenediamine) (PoPD) by using molten-salt as a template. The as-prepared NPCs exhibit hierarchically micro-nanometric porous structure and unprecedented nitrogen content (14.86 wt%). The micrometric pores are interconnected which form from the micrometric salt droplets during carbonization, while the nanopores are generated by the exclusion of small molecular gases. This unique structure and high nitrogen content endows the NPCs with excellent specific capacitance (364.93 F g−1 at 2 mV s−1) and good cycling stability (92.3% capacitance retention at 10 A g−1 after 5000 cycles) in 6 M KOH electrolyte. Moreover, the symmetric supercapacitor array fabricated with the NPCs can easily power a light-emitting diode (LED), demonstrating the practical application of the NPCs in energy storage.

As a promising two-dimensional (2D) conjugated polymer, polymeric carbon nitride (CN) is attracting dramatically increasing interest due to its unusual properties, facile synthesis from abundant and inexpensive starting materials, and promising applications ranging from (photo)catalysis, and photoelectrochemistry, to biosensors. The polymeric feature and facile synthesis of CN allow easy engineering of its structure at the molecular level. For instance, the moderate reactivity of CN at the interface, together with the aromatic π-conjugated framework and intralayer hydrogen bonds, provides ample possibilities to control its molecular structure and properties to meet task-specific applications. This review summarizes and highlights a panorama of the latest advancements related to the design and construction of the molecular structure of CN, such as by doping and copolymerization, engineering of the polymerization degree, coordination interaction, covalent and noncovalent functionalization, and modulation of intralayer hydrogen bonding. Beyond photocatalysis, the emerging applications of CN are also briefly discussed with a special emphasis on sensing, bioimaging and biotherapy, smart responsive systems and photoelectrochemical devices. This review ends with perspectives on the challenges and future prospects of molecular engineering of CN.

Graphite-phase polymeric carbon nitride (GPPCN) has emerged as a promising metal-free material toward optoelectronics and (photo)catalysis. However, the insolubility of GPPCN remains one of the biggest impediments toward its potential applications. Herein, we report that GPPCN could be dissolved in concentrated sulfuric acid, the first feasible solvent so far, due to the synergistic protonation and intercalation. The concentration was up to 300 mg/mL, thousands of time higher than previous reported dispersions. As a result, the first successful liquid-state NMR spectra of GPPCN were obtained, which provides a more feasible method to reveal the finer structure of GPPCN. Moreover, at high concentration, a liquid crystal phase for the carbon nitride family was first observed. The successful dissolution of GPPCN and the formation of highly anisotropic mesophases would greatly pave the potential applications such as GPPCN-based nanocomposites or assembly of marcroscopic, ordered materials.

Graphite-phase polymeric carbon nitride (GPPCN) is one kind of new organic semiconductor for photoelectric conversion, photocatalysis and other important catalytic reactions. However, the low surface area of bulk GPPCN limits its potential applications. Here, we report the preparation of porous GPPCN using industrially available calcium carbonate particles as the hard template; these are not only low-cost, but also easily removed by dilute hydrochloric acid. Interestingly, upon engineering the w/w ratio of template to GPPCN precursor along with the template sizes, our approach resulted in increases of about 4 and 7.5 times in the cathodic photocurrent under visible light (λ > 420 nm) irradiation compared with bulk GPPCN when biased at −0.2 V and 0 V (vs. Ag/AgCl), respectively. These photoelectrochemical activities were higher than those of porous GPPCN obtained by all other reported techniques including the common strategy of using silica nanoparticle templates. This study opens a new avenue to explore the fascinating GPPCN materials for solar energy conversion and environmental remediation, especially for large-scale industrial applications.

The oxygen reduction reaction (ORR) is one of the crucial reactions in fuel cells and metal–air batteries. Heteroatom doped carbon spheres can serve as alternative low-cost non-metal electrocatalysts for ORR. Herein, we developed an effective route to the synthesis of uniform and electrochemically active B-doped hollow carbon nanospheres (BHCSs). BHCSs were synthesized via the carbonization of a boric phenolic resin supported by SiO2, followed by etching the SiO2 template. The content of B, B dopant species and specific surface area were adjusted by changing the content of the B precursor and the calcination temperature. Moreover, their influence on the performance of electrocatalytic activity was explored. It was found that, among these B-doping type materials (BC2O, BCO2, B4C and BC3), B–C bonds (B4C and BC3) played a crucial role on improving the electrocatalytic activity. Compared with the hollow carbon nanospheres (HCSs), a 70 mV positive shift of the onset potential and 1.7 times kinetic current density could be clearly observed with BHCSs. In addition, the BHCSs revealed better stability and methanol tolerance than commercial Pt/C (HiSPEC™ 3000, 20%). Thus, the as-prepared BHCSs, as inexpensive and efficient non-metal ORR catalysts, may have a promising application in direct methanol fuel cells.

A hydrogen bond-driven supramolecular strategy to synthesize multiphase-Fe anchoring on hierarchical N-doped graphitic carbon was proposed. As a result, the as-obtained catalysts showed unusual trifunctional activities in the oxygen reduction reaction, oxygen evolution reaction and hydrogen evolution reaction, even surpassing noble-metal catalysts such as Pt/C and RuO2.

The vascular endothelial growth factor (VEGF) induces pathological angiogenetic ocular diseases. It is a scientific challenge to develop carriers for the controlled release of inhibitors for VEGF present in the back of the eye domain. Carbon dots (C-dots) functionalized with the VEGF aptamer are introduced and the hybrid nanoparticles are used for ocular nanomedicine. The C-dots are applied as effective carriers of the anti-VEGF aptamer across the cornea, yielding therapeutic levels upon topical administration. The hybrids show no toxicity for both in vitro and in vivo murine animal model, and further enable noninvasive intraocular concentration monitoring through the C-dots inherent fluorescence. In addition, the hybrid C-dots effectively inhibit VEGF-stimulated angiogenesis in choroidal blood vessels. This inhibition is comparable to two commercially available anti-VEGF drugs, bevacizumab and aflibercept. The hybrid aptamer-modified C-dots provide a versatile nanomaterial to treat age-related macular degeneration and diabetic retinopathy.