Modular CRISPR/Cas12a synergistic activation platform for detection and logic operations.

The revolutionary technology of CRISPR/Cas has reshaped the landscape of molecular biology and molecular engineering. This tool is of interest to researchers in multiple fields, including molecular diagnostics, molecular biochemistry circuits, and information storage. As CRISPR/Cas spreads to more niche areas, new application scenarios and requirements emerge. Developing programmability and compatibility of CRISPR/Cas becomes a critical issue in the new phase. Here, we report a redundancy-based modular CRISPR/Cas12a synergistic activation platform (MCSAP). The position, length, and concentration of the redundancy in the split DNA activators can finely regulate the activity of Cas12a. With the redundant structure as an interface, MCSAP serves as a modular plug-in to seamlessly integrate with the upstream molecular network. MCSAP successfully performs three different tasks: nucleic acid detection, enzyme detection, and logic operation. MCSAP can work as an effector for different molecular networks because of its compatibility and programmability. Our platform provides powerful yet easy-to-use tools and strategies for the fields of DNA nanotechnology, molecular engineering, and molecular biology.

Time-Controlled Authentication Strategies for Molecular Information Transfer.

Modern cryptography based on computational complexity theory is mainly constructed with silicon-based circuits. As DNA nanotechnology penetrates the molecular domain, utilizing molecular cryptography for data access protection in the biomolecular domain becomes a unique approach to information security. However, building security devices and strategies with robust security and compatibility is still challenging. Here, this study reports a time-controlled molecular authentication strategy using DNAzyme and DNA strand displacement as the basic framework. A time limit exists for authorization and access, and this spontaneous shutdown design further protects secure access. Multiple hierarchical authentications, temporal Boolean logic authentication, and enzyme authentication strategies are constructed based on DNA networks'good compatibility and programmability. This study gives proof of concept for the detection and protection of bioinformation about single nucleotide variants and miRNA, highlighting their potential in biosensing and security protection.

Development of a fluorescent ligand that can illuminate nuclear G-quadruplexes and modulate oncogene expression.

In this study, we developed a promising dual-function fluorescent ligand termed KS-1 by a slight structural modification on a reported carbazole-based scaffold. KS-1 was then found to mainly bind and illuminate the nuclear DNA G-quadruplexes (G4s) in a sandwich-like interacting mode, and also effectively modulate the oncogene expression through a G4-mediated manner. Furthermore, KS-1 was proved to inhibit cancer cell growth either in 2D monolayer cells or 3D multicellular tumor spheroids. To be noted, this ligand could overcome the shortcomings of other reported dual-function ligands that appeared to accumulate in the lysosomes or mitochondria, and may be used as a theranostic agent in the future.

Development of a fluorescent ligand that specifically binds to the c-MYC G-quadruplex by migrating the benzene group on a carbazole-benzothiazolium scaffold.

c-MYC is one of the most important oncogenes, which is overexpressed in many cancers, and is highly related to development, metastasis, and drug resistance of cancers. The G4 structure in the promoter of c-MYC oncogene contributes a lot to the gene transcriptional mechanism. Small-molecule ligands binding to the c-MYC G4 appear to be a new class of anticancer agents. However, selective ligands for the c-MYC G4 over other G4s have been rarely reported. In this study, we reported a novel fluorescent ligand by migrating the benzene group on a carbazole-benzothiazolium scaffold, which was demonstrated to exhibit considerable specificity to the c-MYC G4, which was distinguished from other small-molecule ligands. The further cellular experiments suggested that this ligand may indeed target the promoter G4 and cause apparent transcriptional inhibition of the c-MYC oncogene instead of other G4-mediated oncogenes, which thereby resulted in cancer cell growth inhibition. Collectively, this study provided a good example for developing specific c-MYC G4 ligands, which may further develop into an effective anticancer agent that inhibit the c-MYC expression.

Discovery of a near-infrared fluorescent probe for G-quadruplexes by exploiting the concept of unfolding-intramolecular-aggregation-induced emission.

In the very recent years, the concept of disaggregation-induced emission (DIE) has been applied to design G4 probes, thereby rendering several fluorophores that may suffer from aggregation-induced quenching (ACQ) to develop into desirable G4-selective probes. However, the design idea based on DIE was often limited by the instability and irreversibility of the "intermolecular" aggregation/disaggregation process. In this study, a self-folded, near-infrared fluorescent probe for selectively illuminating G4s was engineered. This probe restored its fluorescence via unfolding of its intramolecular aggregation (UIA) mediated by distinctive G4 binding, which may display more controllable background emission as well as more promising ability to track G4 forming dynamics as compared to the reported DIE probes. Altogether, this study provided insights into the development of new types of applicable G4 selective fluorescent probes.

Combination Therapy with a TLR7 Agonist and a BRD4 Inhibitor Suppresses Tumor Growth via Enhanced Immunomodulation.

JQ-1 is a typical BRD4 inhibitor with the ability to directly fight tumor cells and evoke antitumor immunity via reducing the expression of PD-L1. However, problems arise with the development of JQ-1 in clinical trials, such as marked lymphoid and hematopoietic toxicity, leading to the investigation of combination therapy. SZU-101 is a TLR7 agonist designed and synthesized by our group with potent immunostimulatory activity. Therefore, we hypothesized that combination therapy of SZU-101 and JQ-1 would target innate immunity and adaptive immunity simultaneously, to achieve a better antitumor efficacy than monotherapy. In this study, the repressive effects of the combination administration on tumor growth and metastasis were demonstrated in both murine breast cancer and melanoma models. In 4T1 tumor-bearing mice, i.t. treatment with SZU-101 in combination with i.p. treatment with JQ-1 suppressed the growth of tumors at both injected and uninjected sites. Combination therapy increased M1/M2 ratio in TAMs, decreased PD-L1 expression and promoted the recruitment of activated CD8+ T cells in the TME. In summary, the improved therapeutic efficacy of the novel combination therapy appears to be feasible for the treatment of a diversity of cancers.

Allosteric Nucleic Acid Enzyme: A Versatile Stimuli-Responsive Tool for Molecular Computing and Biosensing Nanodevices.

Allostery is a naturally occurring mechanism in which effector binding induces the modulation and fine control of a related biomolecule function. Deoxyribozyme (DNAzyme) with catalytic activity and substrate recognition ability is ideal to be regulated by allosteric strategies. However, the current regulations frequently confront various obstacles, such as severe activity decay, signal leakage, and limited effectors. In this work, a rational regulation strategy for developing versatile effectors-responsive allosteric nucleic acid enzyme (ANAzyme) by introducing an allosteric domain in response to diverse effectors is established. The enzyme-like activity of this re-engineered ANAzyme can be modulated in a more predictable and fine way compared with the previous DNAzyme regulation strategies. Based on the allosteric strategy, the construction of allosterically coregulatory nanodevices and a series of basic logic gates and logic circuits are achieved, demonstrating that the proposed ANAzyme-regulated strategy showed great potential in molecular computing. Given these facts, the rational design of ANAzyme with the allosteric domain presented here can expand the available toolbox to develop a variety of stimuli-responsive allosteric DNA materials, including molecular machines, computing systems, biosensing platforms, and gene-silencing tools.

Optical analysis of aligned Ni nanowire arrays with different degree of oxidation for terahertz polarizer application.

The optical properties of aligned nickel nanowire arrays (NiNWAs) with different degrees of oxidation for terahertz (THz) polarizer applications have been investigated by using THz time-domain spectroscopy. In frequency-domain spectra, the full width at half maxima of transmitted peaks was broadened and the peak positions have a blue shift with increasing oxidation levels, besides the enhancement in peak intensity. It is indicated that the oxidation of Ni nanowires (NWs) has a significant influence on the interaction between Ni NWs and THz wave. The transmittance of the aligned NiNWAs increases with annealing temperature increasing. Conversely, the degree of polarization and extinction ratio (ER) decreases. A corresponding relationship between the change of ER and degree of oxidation is summarized by means of thermogravimetric analysis. The change of ER for the annealing sample with the degree of oxidation of 0.507% is 27.32%, which induced the polarization properties of aligned NiNWAs to be sensitive to the oxidation of Ni NWs. These findings can provide new positive features in the development of future polarization-based device applications for THz electronics and photonics.

Regulating the Electronic Structure of Ni Sites in Ni(OH)2 by Ce Doping and Cu(OH)2 Coupling to Boost 5-Hydroxymethylfurfural Oxidation Performance.

Biomass is a sustainable and renewable resource that can be converted into valuable chemicals, reducing the demand for fossil energy. 5-Hydroxymethylfurfural (HMF), as an important biomass platform molecule, can be converted to high-value-added 2,5-furandicarboxylic acid (FDCA) via a green and renewable electrocatalytic oxidation route under mild reaction conditions, but efficient electrocatalysts are still lacking. Herein, we rationally fabricate a novel self-supported electrocatalyst of core-shell-structured copper hydroxide nanowires@cerium-doped nickel hydroxide nanosheets composite nanowires on a copper mesh (CuH_NWs@Ce:NiH_NSs/Cu) for electrocatalytically oxidizing HMF to FDCA. The integrated configuration of composite nanowires with rich interstitial spaces between them facilitates fast mass/electron transfer, improved conductivity, and complete exposure of active sites. The doping of Ce ions in nickel hydroxide nanosheets (NiH_NSs) and the coupling of copper hydroxide nanowires (CuH_NWs) regulate the electronic structure of the Ni active sites and optimize the adsorption strength of the active sites to the reactant, meanwhile promoting the generation of strong oxidation agents of Ni3+ species, thereby resulting in improved electrocatalytic activity. Consequently, the optimal CuH_NWs@Ce:NiH_NSs/Cu electrocatalyst is able to achieve a HMF conversion of 98.5% with a FDCA yield of 97.9% and a Faradaic efficiency of 98.0% at a low constant potential of 1.45 V versus reversible hydrogen electrode. Meanwhile, no activity attenuation can be found after 15 successive cycling tests. Such electrocatalytic performance suppresses most of the reported Cu-based and Ni-based electrocatalysts. This work highlights the importance of structure and doping engineering strategies for the rational fabrication of high-performance electrocatalysts for biomass upgrading.

Non-fused imidazole-biphenyl analogs repress triple-negative breast cancer growth by mainly stabilizing the c-MYC G-quadruplex via a multi-site binding mode.

As oncogene c-MYC is abnormally expressed during TNBC pathogenesis, stabilizing its promoter G-quadruplex (G4), which may thus inhibit c-MYC expression and promote DNA damage, may be a potential anti-TNBC strategy. However, large quantities of potential G4-forming sites exist in the human genome, which represents a potential drug selectivity problem. In order to achieve better recognition for c-MYC G4, we herein presented a new approach of designing small-molecule ligands by linking tandem aromatic rings with the c-MYC G4 selective binding motifs. Thus, a series of non-fused, conformation-tunable imidazole-biphenyl analogs were designed and synthesized. Among them, the optimal ligand appeared more effective on stabilizing c-MYC G4 than other types of G4s possibly through an adaptive, multi-site binding mode involved of end-stacking, groove-binding and loop-interacting. Then, the optimal ligand exerted good inhibitory activity on c-MYC expression and induced remarkable DNA damage, leading to the occurrence of G2/M phase arrest, apoptosis and autophagy. Furthermore, the optimal ligand exhibited potent antitumor effects in a TNBC xenograft tumor model. To sum up, this work offers new insights for the development of selective c-MYC G4 ligands against TNBC.

Discovery of a minimalistic DIE-based fluorescent probe for detection of parallel G-quadruplex forms.

G-quadruplexes (G4s) are considered to be involved in some key biological processes, leading to the development of a large number of G4 fluorescent probes, which offer possibilities to study G4 dynamics as well as their biological roles. However, the structures of G4s show high polymorphism, which can be classified into parallel, hybrid and antiparallel forms, and the probes targeting a certain topology are limited. In this study, we have developed a minimalistic fluorescent probe by exploiting the disaggregation-induced emission (DIE) principle. The further studies demonstrated that this probe exhibited promising selectivity toward parallel DNA and RNA G4 forms in vitro. Moreover, it was found that this probe could be applied to map the RNA G4s that always form into parallel topologies in live cells, which distinguished it from other reported DIE-based probes that often targeted the mitochondrial or nuclear DNA G4s. To the best of our knowledge, this was the first DIE-based fluorescent probe for mapping cellular RNA G4s.

A "Trojan Horse" Strategy: The Preparation of Bile Acid-Modifying Irinotecan Hydrochloride Nanoliposomes for Liver-Targeted Anticancer Drug Delivery System Study.

The bile acid transport system is a natural physiological cycling process between the liver and the small intestine, occurring approximately 6-15 times during the day. There are various bile acid transporter proteins on hepatocytes that specifically recognize bile acids for transport. Therefore, in this paper, a novel liposome, cholic acid-modified irinotecan hydrochloride liposomes (named CA-CPT-11-Lip), was prepared based on the "Trojan horse" strategy. The liposomes preparation process was optimized, and some important quality indicators were investigated. The distribution of irinotecan hydrochloride in mice was then analyzed by high-performance liquid chromatography (HPLC), and the toxicity of liposomes to hepatocellular carcinoma cells (HepG-2) was evaluated in vitro. As a result, CA-CPT-11-Lip was successfully prepared. It was spherical with a particle size of 154.16 ± 4.92 nm, and the drug loading and encapsulation efficiency were 3.72 ± 0.04% and 82.04 ± 1.38%, respectively. Compared with the conventional liposomes (without cholic acid modification, named CPT-11-Lip), CA-CPT-11-Lip had a smaller particle size and higher encapsulation efficiency, and the drug accumulation in the liver was more efficient, enhancing the anti-hepatocellular carcinoma activity of irinotecan hydrochloride. The novel nanoliposome modified by cholic acid may help to expand the application of irinotecan hydrochloride in the treatment of hepatocellular carcinoma and construct the drug delivery system mode of drug liver targeting.

A Novel Drug Delivery System: Hyodeoxycholic Acid-Modified Metformin Liposomes for Type 2 Diabetes Treatment.

Metformin is a first-line drug for the clinical treatment of type 2 diabetes; however, it always leads to gastrointestinal tolerance, low bioavailability, short half-life, etc. Liposome acts as an excellent delivery system that could reduce drug side effects and promote bioavailability. Hyodeoxycholic acid, a cholesterol-like structure, can regulate glucose homeostasis and reduce the blood glucose levels. As an anti-diabetic active ingredient, hyodeoxycholic acid modifies liposomes to make it overcome the disadvantages of metformin as well as enhance the hypoglycemic effect. By adapting the thin-film dispersion method, three types of liposomes with different proportions of hyodeoxycholic acid and metformin were prepared (HDCA:ME-(0.5:1)-Lips, HDCA:ME-(1:1)-Lips, and HDCA:ME-(2:1)-Lips). Further, the liposomes were characterized, and the anti-type 2 diabetes activity of liposomes was evaluated. The results from this study indicated that three types of liposomes exhibited different characteristics-Excessive hyodeoxycholic acid decreased encapsulation efficiency and drug loading. In the in vivo experiments, liposomes could reduce the fasting blood glucose levels, improve glucose tolerance, regulate oxidative stress markers and protect liver tissue in type 2 diabetic mice. These results indicated that HDCA:ME-(1:1)-Lips was the most effective among the three types of liposomes prepared and showed better effects than metformin. Hyodeoxycholic acid can enhance the hypoglycemic effect of metformin and play a suitable role as an excipient in the liposome.

Formation of Interfacial Cu-[OX ]-Ce Structures with Oxygen Vacancies for Enhanced Electrocatalytic Nitrogen Reduction.

Electrochemical nitrogen reduction powered by renewable electricity is a promising strategy to produce ammonia. However, the lack of efficient yet cheap electrocatalysts remains the biggest challenge. Herein, hybrid Cu2 O-CeO2 -C nanorods are prepared on copper mesh through a metal-organic framework template route. The Cu-loaded Ce-MOF is thermally converted to Cu2 O-CeO2 heterojunctions with interfacial Cu-[OX ]-Ce structures embedded in carbon. Theoretical calculations reveal the lower formation energy of oxygen vacancies in Cu-[OX ]-Ce structures than in the Cu2 O or CeO2 phase. The Cu-[OX ]-Ce structures with oxygen vacancies enable the formation of interfacial electron-rich Cu(I) species which show significantly enhanced performance toward electrocatalytic nitrogen reduction with an NH3 yield of 6.37 × 10-3  µg s-1 cm-2 and a Faradaic efficiency of 18.21% in 0.10 m KOH at -0.3 V versus reversible hydrogen electrode. This work highlights the importance of modulation of charge distribution of Cu-based electrocatalysts to boost the activity toward nitrogen reduction.

Snapshot ptychography on array cameras.

We use convolutional neural networks to recover images optically down-sampled by 6.7 × using coherent aperture synthesis over a 16 camera array. Where conventional ptychography relies on scanning and oversampling, here we apply decompressive neural estimation to recover full resolution image from a single snapshot, although as shown in simulation multiple snapshots can be used to improve signal-to-noise ratio (SNR). In place training on experimental measurements eliminates the need to directly calibrate the measurement system. We also present simulations of diverse array camera sampling strategies to explore how snapshot compressive systems might be optimized.

Discovery of a fluorescent, long chain-bridged bispurine that selectively targets the c-MYC G-quadruplex.

G-quadruplexes (G4s) are special nucleic acid structures which are involved in the regulation of some key biological events like transcription and translation, which are now treated as promising therapeutic targets for cancers. Stabilizing the promoter G4 by small-molecule ligands can suppress the c-MYC oncogene transcription, thus inhibiting cancer cell proliferation. So far, targeting the very structure, a number of ligands have been reported. However, most of them showed unsatisfactory specificity to the c-MYC G4 over other G4s, resulting in uncertain side effects. In this contribution, we discovered a new class of bispurines bridged with flexible hydrocarbon chains, which presented somewhat selectivity to the c-MYC G4 possibly by adaptive binding, which then showed clear inhibition on the c-MYC expression rather than other G4-driven oncogenes. Moreover, these novel molecules had the potential to fluorescently label G4s. We believed that this study may shed light on the discovery of new functional small molecules targeting a specific G4 structure.

Endonuclease IV-Regulated DNAzyme Motor for Universal Single-nucleotide Variation Discrimination.

Single-nucleotide variation (SNV) detection plays significant roles in disease diagnosis and treatment. Generally, auxiliary probe, restricted design rules, complicated detection system, and repeated experimental parameter optimization are needed to obtain satisfactory tradeoff between sensitivity and selectivity for SNV discrimination, especially when different mutant sites need to be distinguished. To overcome these limitations, we developed a universal, straightforward, and relatively cheap SNV discrimination strategy, which simultaneously possessed high sensitivity and selectivity. The excellent performance of this strategy was ascribed to the SNV discrimination property of endonuclease IV (Endo IV) and the different hydrolysis behavior between free deoxyribozyme (DNAzyme) and the trapped DNAzyme to the substrates modified on gold nanoparticles (AuNPs). When Endo IV recognized the mutant-type target (MT), free DNAzyme was released from the probe, and the DNAzyme motor was activated with the help of cofactor Mn2+ to generate an amplified fluorescence signal. On the contrary, the wild-type target (WT) could not effectively trigger the DNAzyme motor. Moreover, for different SNV types, the corresponding probe could be designed by simply changing the sequence hybridized with the target and retaining the DNAzyme sequence. Thus, the fluorescence signal generation system does not need to change for different SNV targets. Five clinical-related SNVs were determined with the limit of detection (LOD) ranging from 0.01 to 0.05%, which exhibited competitive sensitivity over existing SNV detection methods. This strategy provided another insight into the properties of Endo IV and DNAzyme, expanded the applications of DNAzyme motor, and has great potential to be used for precision medicine.

Boosting Hydrogen Evolution Reaction via Electronic Coupling of Cerium Phosphate with Molybdenum Phosphide Nanobelts.

Molybdenum phosphide (MoP) is regarded as one of the most promising alternatives to noble-metal based electrocatalysts for efficient hydrogen evolution reaction (HER) due to its similar d-band electronic structure to noble metals and tunable features associated with phase and composition. However, it still remains a great challenge to construct MoP electrocatalysts with abundant active sites that possess ideal H binding strength to promote catalytic performance. In this work, it is found that by anchoring a rare earth compound, cerium phosphate (CePO4 ) on MoP (CePO4 /MoP), the stabilized Ce3+ in CePO4 can significantly boost the formation of oxygen vacancies in ceria (CeO2 ) in situ formed on CePO4 surface during HER, which effectively regulates the d-band electronic density-of-states of MoP, increases the numbers of active sites, and promotes the vectorial electron transfer, therefore greatly enhancing the HER performance of MoP. The optimized CePO4 /MoP/carbon cloth (CC) electrocatalyst exhibits a significantly improved HER performance with an overpotential of 48 mV at 10 mA cm-2 and a Tafel slope of 38 mV dec-1 , about two times better than the HER performance of MoP catalyst without CePO4 (with an overpotential >80 mV dec-1 at 10 mA cm-2 ), very close to commercial Pt/C catalyst.

Multi-Elemental Electronic Coupling for Enhanced Hydrogen Generation.

A robust polyaniline-assisted strategy is developed to construct a self-supported electrode constituting a nitrogen, phosphorus, sulfur tri-doped thin graphitic carbon layer encapsulated sulfur-doped molybdenum phosphide nanosheet array (NPSCL@S-MoP NSs/CC) with accessible nanopores, desirable chemical compositions, and stable composite structure for efficient hydrogen evolution reaction (HER). The multiple electronic coupling effects of S-MoP with N, P, S tri-dopants afford effective regulation on their electrocatalytic performance by endowing abundant accessible active sites, outstanding charge-transfer property, and d-band center downshift with a thermodynamically favorable hydrogen adsorption free energy (ΔGH* ) for efficient hydrogen evolution catalysis. As a result, the NPSCL@S-MoP NSs/CC electrode exhibits overpotentials as low as 65, 114, and 49 mV at a geometric current density of 10 mA cm-2 and small Tafel slopes of 49.5, 69.3, and 53.8 mV dec-1 in 0.5 m H2 SO4 , 1.0 m PBS, and 1.0 m KOH, respectively, which could maintain 50 h of stable performance, almost outperforming all MoP-based catalysts reported so far. This study provides a valuable methodology to produce interacted multi-heteroatomic doped graphitic carbon-transition metal phosphide electrocatalysts with superior HER performance in a wide pH range.

New substituted quinoxalines inhibit triple-negative breast cancer by specifically downregulating the c-MYC transcription.

Conventional chemotherapy remains the primary treatment option for triple-negative breast cancer (TNBC). However, the current chemotherapeutic drugs have limited effects on TNBC, and often lead to serious side effects as well as drug resistance. Thus, more effective therapeutic options are sorely needed. As c-MYC oncogene is highly expressed during TNBC pathogenesis, inhibiting c-MYC expression would be an alternative anti-TNBC strategy. In this study, we designed and synthesized a serial of quinoxaline analogs that target c-MYC promoter G-quadruplex (G4), which is believed to be a repressor of c-MYC transcription. Among them, a difluoro-substituted quinoxaline QN-1 was identified as the most promising G4-stabilizing ligand with high selectivity to c-MYC G4 over other G4s, which is distinguished from many other reported ligands. Intracellular studies indicated that QN-1 induced cell cycle arrest and apoptosis, repressed metastasis and inhibited TNBC cell growth, primarily due to the downregulation of c-MYC transcription by a G4-dependent mechanism. Notably, inhibition by QN-1 was significantly greater for c-MYC than other G4-driven genes. Cancer cells with c-MYC overexpression were more sensitive to QN-1, relative to normal cells. Furthermore, QN-1 effectively suppressed tumor growth in a TNBC mouse model. Accordingly, this work provides an alternative strategy for treating TNBC.