Chemistry

Self-assembled DNA nanospheres, as versatile and ideal vehicles, have offered new opportunities to create intelligent delivery systems for precise bioimaging and cancer therapy, due to their good biostability and cell permeability, large loading capacity, and programmable self–assembly behaviors. DNA nanospheres can be synthesized by the self–assembly of Y–shaped DNA monomers, ultra–long single-stranded DNA (ssDNA), and even metal–DNA coordination. Interestingly, they are size–controllable by varying some parameters including concentration, reaction time, and mixing ratio. This review summarizes the design of DNA nanospheres and their extensive biomedical applications. First, the characteristics of DNA are briefly introduced, and different DNA nanostructures are mentioned. Then, the design of DNA nanospheres is emphasized and classified into three main categories, including Y–shaped DNA unit self-assembly by Watson–Crick base pairing, liquid crystallization and the dense packaging of ultra–long DNA strands generated via rolling circle amplification (RCA), and metal–DNA coordination–driven hybrids. Meanwhile, the advantages and disadvantages of different self–assembled DNA nanospheres are discussed, respectively. Next, the biomedical applications of DNA nanospheres are mainly focused on. Especially, DNA nanospheres serve as promising nanocarriers to deliver functional nucleic acids and drugs for biosensing, bioimaging, and therapeutics. Finally, the current challenges and perspectives for self-assembled DNA nanospheres in the future are provided. Full article

Coffee skins, a cheap, agricultural waste, were carbonized in a tubular furnace under a nitrogen stream and then ball milled to fabricate coffee skin-carbon-nanoparticles (CCNPs). SEM showed 35.6–41.6 nm particle size. The 26.64 and 43.16 peaks in the XRD indicated a cubic graphite lattice. The FT-IR broadband revealed a 2500–3500 cm⁻¹ peak, suggesting an acidic O-H group. CCNPs possessed a type-H3-loop in the N₂-adsorption-desorption analysis, with a surface of 105.638 m² g⁻¹. Thereafter, CCNPs were tested for ciprofloxacin (CPXN) adsorption, which reached equilibrium in 90 min. CCNPs captured 142.6 mg g⁻¹ from 100 mg L⁻¹ CPXN, and the 5:12 sorbent mass-to-solution volume ratio was suitable for treating up to 75 mg L⁻¹ contamination. The q_t dropped from 142.6 to 114.3 and 79.2 mg g⁻¹ as the temperature rose from 20 °C to 35 °C and 50 °C, respectively, indicating exothermic adsorption. CPXN removal efficiency decreased below pH 5.0 and above pH 8.0. Kinetically, CPXN adsorption fits the second-order model and is controlled by the liquid-film mechanism, indicating its preference for the CCNPs’ surface. The adsorption agreement with the liquid-film and Freundlich models implied the ease of CPXN penetration into the CCNP inner shells and the multilayered accumulation of CPXN on the CCNPs’ surface. The negative ∆H° and ∆G° revealed the exothermic nature and spontaneity of CPXN adsorption onto the CCNP. The CCNPs showed an efficiency of 95.8% during four consecutive regeneration-reuse cycles with a relative standard deviation (RSD) of 3.1%, and the lowest efficiency in the fourth cycle was 92.8%. Full article

Surfactants are amphiphilic molecules with the ability to modify the surface tension between two surfaces. They can be obtained by various methods, the main one being synthetic, from petroleum-based substrates. Their universal use in a wide range of fields has created a global market and, consequently, ecological, and economic expectations for their production. Biocatalyzed processes, involving enzymes, can address this objective with processes complying with the principles of green chemistry: energy saving, product selectivity, monodispersity, and reduction in the use of solvents, with energy eco-efficiency. For example, fatty-acid carbohydrate esters are biobased surfactants that can be synthesized by lipases. In this work, we were interested in the synthesis of D-glucose lauric ester, which presents interesting properties described in the literature, with Aspergillus niger lipase, rarely described with sugar substrates. We optimized the synthesis for different parameters and reaction media. This lipase appeared to be highly selective for 6-O-lauroyl-D-glucopyranose. However, the addition of DMSO (dimethyl sulfoxide) as a co-solvent displays a duality, increasing yields but leading to a loss of selectivity. In addition, DMSO generates more complex and energy-intensive purification and processing steps. Consequently, a bio-sourced alternative as co-solvent with 2MeTHF3one (2-methyltetrahydrofuran-3-one) is proposed to replace DMSO widely described in the literature. Full article

Decreasing the sensitivity towards detonation of high-energy materials (HEMs) is the ultimate goal of numerous theoretical and experimental studies. It is known that positive electrostatic potential above the central areas of the molecular surface is related to high sensitivity towards the detonation of high-energy molecules. Coordination compounds offer additional structural features that can be used for the adjustment of the electrostatic potential values and sensitivity towards detonation of this class of HEM compounds. By a careful combination of the transition metal atoms and ligands, it is possible to achieve a fine-tuning of the values of the electrostatic potential on the surface of the chelate complexes. Here we combined Density Functional Theory calculations with experimental data to evaluate the high-energy properties of tris(3-nitropentane-2,4-dionato-κ2 O,O′) (nitro-tris(acetylacetonato)) complexes of Cr(III), Mn(III), Fe(III), and Co(III). Analysis of the Bond Dissociation Energies (BDE) of the C-NO₂ bonds and Molecular Electrostatic Potentials (MEP) showed that these compounds may act as HEM molecules. Analysis of IR spectra and initiation of the Co(AcAc-NO₂)₃ complex in the open flame confirmed that these compounds act as high-energy molecules. The measured heat of combustion for the Co(AcAc-NO₂)₃ complex was 14,133 J/g, which confirms the high-energy properties of this compound. The results also indicated that the addition of chelate rings may be used as a new tool for controlling the sensitivity towards the detonation of high-energy coordination compounds. Full article

The desirable properties of the sophisticated fluorescent pH probe are ratiometric detection properties and a wide detection range. In this study, three types of fluorophores with different fluorescence properties were assembled on a DNA origami nanostructure. DNA nanostructure has the advantage of being a scaffold that can assemble different types of fluorophores with control over their number and position. The defined number of three different fluorophores, i.e., pH-sensitive fluorescein (CF) and Oregon Green (OG), and pH-insensitive tetramethylrhodamine (CR), assembled on the DNA scaffold provided a ratiometric fluorescent pH probe with a wide pH detection range that could cover the variation of intracellular pH. Full article

Apurinic/apyrimidinic endonuclease 1 (APE1), also known as redox factor-1 (Ref-1), is a multifunctional protein that exists widely in living organisms. It can specifically recognize and cleave the DNA in apurinic/apyrimidinic (AP) sites in the base excision repair (BER) pathway, as well as regulate the expression of genes to activate some transcription factors. The abnormal expression and disruptions in the biological functions of APE1 are linked to a number of diseases, including inflammation, immunodeficiency, and cancer. Hence, it is extremely desired to monitor the activity of APE1, acquiring a thorough understanding of the healing process of damaged DNA and making clinical diagnoses. Thanks to the advent of DNA nanotechnology, some nanodevices are used to image the activity of APE1 with great sensitivity and simplicity. In this review, we will summarize developments in DNA-nanotechnology-empowered fluorescence imaging in recent years for APE1 activity according to different types of DNA probes, which are classified into linear DNA probes, composite DNA nanomaterials, and three-dimensional (3D) DNA nanostructures. We also highlight the future research directions in the field of APE1 activity imaging. Full article

Natural diamond crystals with a highly porous surface were used as substrates for synthesizing single-phase bimetallic Pt–Co nanoparticles at temperatures of 500 °C and 800 °C. The metal nanoparticles inside the pores were determined to take the form of single-phase Pt_0.50Co_0.50 solid solutions with different degrees of superstructure ordering. A detailed characterization of both nanoalloys revealed a tetragonal symmetry with a space group, P4/mmm. For the sample obtained at 500 °C, the lattice parameters were a = 2.673(2), c = 3.735(3) Å, and c/a = 1.397(1); for the samples obtained at 800 °C, the parameters were—a = 2.688(2), c = 3.697(3) Å, and c/a = 1.375(1). Within the experimental parameters, no significant chemical interaction of the diamond with the Pt–Co particles was identified. The results demonstrate a strong anchoring effect of the metallic material within the etching pores. The successful synthesis of bimetallic Pt–Co particles embedded inside the caverns can facilitate a study of their magnetic properties. The presence of Pt–Co in specific diamond compositions can also be used for marking diamond crystals as a means for their subtle identification, as well as confirming the possibility of capturing significant amounts of metal along with diamonds during their dissolution in the deep Earth. Full article

DNA nanotechnology has been widely used to fabricate precise nanometer-scale machines. In particular, dynamic DNA nanodevices have demonstrated their ability to mimic molecular motions and fluctuations in bion-anomic systems. The elaborately designed DNA nanomachines can conduct a variety of motions and functions with the input of specific commands. A dynamic DNA nanodevice with excellent rigidity and unprecedented processability allows for structural transformation or predictable behavior, showing great potential in tackling single-molecule sensing, drug delivery, molecular systems, and so on. Here, we first briefly introduce the development history of DNA nanotechnology. The driving energy of dynamic DNA nanomachines is also discussed with representative examples. The motor pattern of DNA nanomachines is classified into four parts including translational motion, shear motion, 360° rotation, and complex motion. This review aims to provide an overview of the latest reports on the dynamic DNA nanomachine and give a perspective on their future opportunities. Full article

The solvothermal reaction of Zn(NO₃)₂·4H₂O, 1-OH-2-naphthaldehyde, and 2-methylalanine (mAla) in MeOH leads to the formation of complex {[ZnL₁]}_2n (1) (H₂L₁ = the Schiff-base resulting from the reaction of 1-OH-2-naphthaldehyde and mAla) in good yields. The structure of the neutral species, as determined by single-crystal crystallography, describes a two-dimensional coordination polymer, with repeating {Zn₂} units bridged by syn, anti-carboxylate groups of the Schiff-base ligands. Repeating the same reaction using glycine (gly) instead of mAla leads to the formation of complex {[ZnL₂]·0.33MeOH}_3n (2.0.33MeOH) (H₂L₂ = the Schiff-base resulting from the reaction of 1-OH-2-naphthaldehyde and gly), again in good yields. Complex 2 describes a three-dimensional coordination polymer based on {Zn₂} building blocks, arranged by anti, anti-carboxylate groups in a 3D motif. Complexes 1 and 2 were found to strongly emit at ~435 nm (λ_exc = 317 nm) both in solution and solid state, with complex 2 displaying a slightly longer lifetime of τ_av = 2.45 ns vs. τ_av = 2.02 ns for 1. Full article

The potentialities of mechanochemistry trough extrusion have been investigated for the design of nanosized catalysts and their use in C-C bond-forming reactions. The mechanochemical approach proved successful for the synthesis of supported palladium nanoparticles with mean diameter within 6–10 nm, achieved by the reduction of Pd(II) acetate with ethylene glycol, in the absence of any solvent. A mesoporous N-doped carbon derived from chitin as a renewable biopolymer, was used as a support. Thereafter, the resulting nanomaterials were tested as catalysts to implement a second extrusion based-protocol for the Suzuki-Miyaura cross-coupling reaction of iodobenzene and phenylboronic acid. The conversion and the selectivity of the reaction were 81% and >99%, respectively, with a productivity of the desired derivative, biphenyl, of 41 mmol g_cat⁻¹ h⁻¹. Full article

While fluorescent sensors have been developed for monitoring metal ions in health and diseases, they are limited by the requirement of an excitation light source that can lead to photobleaching and a high autofluorescence background. To address these issues, bioluminescence resonance energy transfer (BRET)-based protein or small molecule sensors have been developed; however, most of them are not highly selective nor generalizable to different metal ions. Taking advantage of the high selectivity and generalizability of DNAzymes, we report herein DNAzyme-based ratiometric sensors for Zn²⁺ based on BRET. The 8-17 DNAzyme was labeled with luciferase and Cy3. The proximity between luciferase and Cy3 permitted BRET when coelenterazine, the substrate for luciferase, was introduced. Adding samples containing Zn²⁺ resulted in a cleavage of the substrate strand, causing dehybridization of the DNAzyme construct, thus increasing the distance between Cy3 and luciferase and changing the BRET signals. Using these sensors, we detected Zn²⁺ in serum samples and achieved Zn²⁺ detection with a smartphone camera. Moreover, since the BRET pair is not the component that determines the selectivity of the sensors, this sensing platform has the potential to be adapted for the detection of other metal ions with other metal-dependent DNAzymes. Full article

In this study, a new modified chitosan conjugate (Chito-TZ) was developed via amide coupling between the acid chloride derivative of the methylthio-thidiazole compound and the free primary amino groups of chitosan. The product was characterized using several instrumental investigations, including Fourier-transform infrared spectroscopy (FT-IR), ¹H-Nuclear magnetic resonance, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). XRD indicated that the crystalline pattern of chitosan was interrupted after chemical modification with the thiadiazole derivative. Broido’s model was used to determine the thermal activation energy E_a, and the results showed that the E_a for the first decomposition region of Chito-TZ is 24.70 KJ mol⁻¹ lower than that required for chitosan (95.57 KJ mol⁻¹), indicating the accelerating effect of the thiadiazole derivative on the thermal decomposition of Chito-TZ. The modified chitosan showed better antibacterial and antifungal activities than the non-modified chitosan; except for seed germination, chitosan was better. The Chito-TZ showed a low MIC value (25–50 µg mL⁻¹) compared to Chito (50–100 µg mL⁻¹). Moreover, the maximum inhibition percentages for plant-pathogenic fungi, Aspergillus niger, Fusarium oxysporum, and Fusarium solani, were attained at a concentration of 300 µg mL⁻¹ with values of 35.4 ± 0.9–39.4 ± 1.7% for Chito and 45.2 ± 1.6–52.1 ± 1.3% for Chito-TZ. The highest germination percentages (%) of broad bean, shoot and root length and weight, and seed vigor index were obtained after Chito treatment with a concentration of 200 µg mL⁻¹ compared to Chito-TZ. Full article

Gene therapy is the ultimate therapeutic technology for diseases related to gene abnormality. However, the use of DNA alone has serious problems, such as poor stability and difficulty in entering target cells. The development of a safe and efficient gene delivery system is the cornerstone of gene therapy. Of particular interest, multifunctional peptides are rationally designed as non-viral vectors for efficient gene delivery. As components of gene delivery vectors, these peptides play critically important roles in skeleton construction, the implementation of targeting strategies, cell membrane penetration, endosome rupture, and nuclear transport. In recent years, the research of functional peptide-based gene delivery vectors has made important progress in improving transfection efficiency. The latest research progress and future development direction of peptide-based gene delivery vectors are reviewed in this paper. Full article

The combined use of di-2-pyridyl ketone ((py)₂CO) with various diols in Mn cluster chemistry has afforded five new compounds, namely, [Mn₁₁O₂(OH)₂{(py)₂CO₂}₅(pd)(MeCO₂)₃(N₃)₃(NO₃)₂(DMF)₄](NO₃)∙2DMF∙H₂O (1∙2DMF∙H₂O), [Mn₁₁O₂(OH)₂{(py)₂CO₂}₅(mpd)(MeCO₂)₃(N₃)₃(NO₃)₂(DMF)₄](NO₃) (2), [Mn₁₂O₄(OH)₂{(py)₂CO₂}₄(mpd)₂(Me₃CCO₂)₄(NO₃)₄(H₂O)₆](NO₃)₂∙2MeCN (3∙2MeCN), [Mn₄(OMe)₂{(py)₂C(OMe)O}₂(2-hp)₂(NO₃)₂(DMF)₂] (4), and [Mn₇{(py)₂CO₂}₄(2-hp)₄(NO₃)₂(DMF)₂](ClO₄)∙DMF (5∙DMF) ((py)₂CO₂²⁻ and (py)₂C(OMe)O⁻ = gem-diol and hemiketal derivatives of di-2-pyridyl ketone, pdH₂ = 1,3-propanediol, mpdH₂ = 2-metly-1,3-propanediol, 2-hpH₂ = 2-(hydroxymethyl)phenol). Complexes 1 and 2 are isostructural, possessing an asymmetric [Mn^III₅Mn^II₆(μ₄-O)(μ₃-O)(μ₃-OH)(μ-OH)(μ₃-OR)₂(μ-OR)₁₀(μ-N₃)]⁸⁺ core. Compound 3 is based on a multilayer [Mn^III₈Mn^II₄(μ₄-O)₂(μ₃-O)₂(μ₃-OH)₂(μ-OR)₁₂]¹⁰⁺ core, while complex 4 comprises a defective dicubane core. The crystal structure of 5 reveals that it is based on an unusual non-planar [Mn^III₅Mn^II₂(μ-OR)₁₂]⁷⁺ core with a serpentine-like topology. Direct current (dc) magnetic susceptibility studies revealed the presence of dominant antiferromagnetic exchange interactions in complex 3, while ferromagnetic coupling between the Mn ions was detected in the case of compound 5. Fitting of the magnetic data for complex 4 revealed weak antiferromagnetic interactions along the peripheral Mn^II∙∙∙Mn^III ions (J_wb = −0.33 (1) cm⁻¹) and ferromagnetic interactions between the central Mn^III∙∙∙Mn^III ions (J_bb = 6.28 (1) cm⁻¹). Full article

Aptamers are artificial oligonucleotides with excellent molecule-targeting ability. Compared with monoclonal antibodies, aptamers have the advantages of low cost, no batch effect, and negligible immunogenicity, making them promising candidates for cancer immunotherapy. To date, a series of aptamer agonists/antagonists have been discovered and directly used to activate immune response, such as immune checkpoint blockade, immune costimulation, and cytokine regulation. By incorporating both tumor- and immune cell-targeting aptamers, multivalent bispecific aptamers were designed to pursue high tumor affinity and enhanced immune efficacy. More importantly, benefiting from feasible chemical modification and programmability, aptamers can be engineered with diverse nanomaterials (e.g., liposomes, hydrogels) and even living immune cells (e.g., NK cells, T cells). These aptamer-based assemblies exhibit powerful capabilities in targeted cargo delivery, regulation of cell–cell interactions, tumor immunogenicity activation, tumor microenvironment remodeling, etc., holding huge potential in boosting immunotherapeutic efficacy. In this review, we focus on the recent advances in aptamer-based immune drug systems (AptIDCs) and highlight their advantages in cancer immunotherapy. The current challenges and future prospects of this field are also pointed out in this paper. Full article

The demand for synthetic bone grafts has increased in recent years. Hydroxyapatite (HA) is one of the highly suitable candidates as a bone graft material due to its excellent biocompatibility and high osteoconductive properties with low toxicity. HA has disadvantageous mechanical strength showing relatively fragile and brittle behavior due to its high hygroscopic properties. This leads to improper mechanical properties for such grafting applications. Therefore, HA should be combined with another material with similar biocompatibility and high hardness, such as SiO₂. In this work, HA/SiO₂ (HAS) composite material was prepared via a hydrothermal method to obtain the high purities of HA with a particle size of approximately 35 nm and around 50% crystallinity. It was found that the addition of SiO₂ stimulated the composite system by forming an orthosilicic acid complex that can reduce the overall solution’s pH, thus contributing to the integrity and stability of the HAS composite. Therefore, higher SiO₂ contents in the HAS composite can enhance its mechanical stability when immersed in simulated body fluid (SBF). Our work demonstrated that HAS can highly improve HA material’s hardness and mechanical stability under immersion of SBF. The Vickers test showed that the 0.05 GPa hardness in 10% SiO₂ increased to 0.35 GPa hardness with the addition of 20% SiO₂. The crystal structures of HAS were analyzed using X-ray diffraction, and the morphology of the HAS composites was observed under electron microscopy. Full article

A stringent DNA probe to profile microRNA (miRNA) expression within a specific cell remains a key challenge in biology. To address this issue, an intracellular ATP-activated Y-DNA probe for accurate imaging of miRNA in living cells was designed. Y-DNA was based on the fabrication of tripartite function modules, which consisted of a folate (FA)-modified targeting module, an ATP aptamer-sealed driver, and a miRNA sensing module. The Y-DNA probe could be specifically activated by ATP after it efficiently internalized into FA-receptor-overexpressed cells based on caveolar-mediated endocytosis, leading to the activation of the miRNA sensing module. The activated Y-DNA probe allowed for the imaging of miRNA in living cells with high sensitivity. The design of the ATP-activated Y-DNA sensor opens the door for bioorthogonal miRNA imaging and promotes the development of various responsive DNA molecular probes with enhanced anti-interference ability for clinical diagnosis. Full article

The pursuit of operational advancements in direct formic acid fuel cells (DFAFCs) necessitates the development of high-performance platinum (Pt)-based catalysts for formic acid electrooxidation (FAOR). However, FAOR on Pt-based catalysts follows a dual pathway mechanism, in which the direct pathway is a preferred route due to its efficient dehydrogenation process. Conversely, the indirect pathway results in the generation of adsorbed CO species, a process that deleteriously poisons the active sites of the catalyst, with CO species only being oxidizable at higher potentials, causing a significant compromise in catalyst performance. Herein, we have successfully synthesized Pt-C₃N₄@CNT, where three Pt clusters are precisely dispersed in a triplet form within the C₃N₄ by virtue of the unique structure of C₃N₄. The mass activity for the direct pathway (0.44 V) delivered a current density of 1.91 A ${\mathrm{mg}}_{\mathrm{Pt}}^{-1}$, while the indirect pathway (0.86 V) had no obvious oxidation peak. The selectivity of Pt-C₃N₄@CNT catalysts for the direct pathway of FAOR was improved due to the special structure of C₃N₄, which facilitates the dispersion of Pt tri-atoms in the structure and the electronic interaction with Pt. In this study, we provide a new strategy for the development of highly active and selective catalysts for DFAFCs. Full article