Solution-phase Approach Research Articles

Assembling Bi3TaO7 nanodots on tubular carbon nitride to boost photocatalytic degradation of tetracycline under visible light irradiation

Due to the development of society, the problem of ecological pollution by the extensive use of antibiotics (tetracycline, ciprofloxacin, etc.) has attracted the broad attention of many scholars. Herein, a novel Bi3TaO7 nanodots (BTO)/tubular carbon nitride (TCN) type-II heterojunction was prepared by a low temperature solution phase approach for tetracycline (TC) degradation under visible light irradiation. The experimental results showed that the as-fabricated BTO/TCN heterostructures exhibited superior degradation rates of TC than that of bare TCN and BTO. The optimal loading amount 0.3 %BTO/TCN sample displayed the highest TC degradation rate of 99.6 % under 120 min of visible light irradiation, which is 1.13 and 1.04 times than that of pure TCN and BTO, respectively. This is due to the unique tubular structure of TCN that can expose more active sites as well as type-II heterojunctions effectively impede the rapid complexation of photogenerated electron pairs under a potential difference. This strategy provides new insights and references for the design of type-II heterojunction construction.

Fructose-mediated single-step synthesis of copper nanofluids with enhanced stability and thermal conductivity for advanced heat transfer applications

A precisely controlled solution-phase approach was employed to synthesize copper nanofluid through the reduction of copper sulfate by fructose in the presence of cetyltrimethylammonium bromide, utilizing a mixture of water and ethylene glycol in 1:1 ratio as the base fluid. We delved into the nanofluid’s thermal conductivity and rheological properties, with a keen interest on particle size and reaction rates that exhibited significant sensitivity to variations in reaction parameters. The homogeneous dispersion of nanoparticles in the base fluid resulted in an augmentation of thermal conductivity to 2.31 Wm−1K−1 for particle loading fraction of 0.19%, with a never before achieved stability of 9 months. This method has proven to be not only straightforward and dependable but also efficient for the rapid synthesis of highly stable Newtonian nanofluids, underscoring the nanofluid’s potential for highly powerful cooling applications.

Lead-Free Nanocrystal Inks for Flexible Optoelectronic Devices

The exploration of AgBiS2 quantum dots (QDs) as an environmentally friendly alternative to previously-explored infrared-absorbing QDs has continued to gain interest in the past few years. Applications in optoelectronic devices are facilitated by colloidally stable inks that can be used to deposit films with favorable material properties on diverse substrates, including flexible substrates applicable to lightweight and wearable sensors. Here, we demonstrate that a rapid biphasic ligand exchange process can be used to make a AgBiS2 QD ink. The properties of deposited films are explored in lateral photoconductive devices and in heterojunction photovoltaic devices. In addition to this, we also demonstrated the use of this environmentally benign QD ink in flexible devices: the photo response was unchanged when the device was flat or bent. These results demonstrate the versatility of solution-phase ligand exchange approaches to QD-based optoelectronic devices.

High-quality integratable microlasers from scalable perovskite heterostructures enabled by solution-phase processing

High-performance transferable and integratable microlasers hold great promise to construct the integrated photonics and optoelectronics. However, the qualified candidates are still being pursued. Herein, a mass-production of low-threshold and wavelength-tunable microlasers that is readily integratable with the optical fiber platform is realized by a two-step solution-phase approach. The demonstration is enabled by the formation of a novel semiconductor heterostructure from halide perovskites featuring the quasi-free-standing and highly emissive properties. Corroborated by the in-situ optical characterization, we reveal that the lateral perovskite heterostructures are constructed through a sequential reaction driven by the surface energy contrast. These perovskite heterostructures exhibit low-threshold and broadband tunable lasing action thanks to the efficient spatial light conversion nature and the facile composition tunability. Taking the merits together, the heterostructure microlasers can be the competitive applicants for photonic integration as demonstrated by the laser-on-fiber configuration.

Improved Access to Potent Anticancer Tubulysins and Linker-Functionalized Payloads Via an All-On-Resin Strategy.

Tubulysins are among the most recent antimitotic compounds to enter into antibody/peptide-drug conjugate (ADC/PDC) development. Thus far, the design of the most promising tubulysin payloads relied on simplifying their structures, e. g., by using small tertiary amide N-substituents (Me, Et, Pr) on the tubuvaline residue. Cumbersome solution-phase approaches are typically used for both syntheses and functionalization with cleavable linkers. p-Aminobenzyl quaternary ammonium (PABQ) linkers were a remarkable advancement for targeted delivery, but the procedures to incorporate them into tubulysins are only of moderate efficiency. Here we describe a novel all-on-resin strategy permitting a loss-free resin linkage and an improved access to super potent tubulysin analogs showing close resemblance to the natural compounds. For the first time, a protocol enables the integration of on-resin tubulysin derivatization with, e. g., a maleimido-Val-Cit-PABQ linker, which is a notable progress for the payload-PABQ-linker technology. The strategy also allows tubulysin diversification of the internal amide N-substituent, thus enabling to screen a tubulysin library for the discovery of new potent analogs. This work provides ADC/PDC developers with new tools for both rapid access to new derivatives and easier linker-attachment and functionalization.

Amino Acid Double-Passivation-Enhanced Quantum Dot Coupling for High-Efficiency FAPbI3 Perovskite Quantum Dot Solar Cells.

Formamidinium lead triiodide (FAPbI3) perovskite quantum dot has outstanding durability, reasonable carrier lifetime, and long carrier diffusion length for a new generation of highly efficient solar cells. However, ligand engineering is a dilemma because of the highly ionized and dynamic characteristics of quantum dots. To circumvent this issue, herein, we employed a mild solution-phase ligand-exchange approach through adding short-chain amino acids that contain amino and carboxyl groups to modify quantum dots and passivate their surface defects during the purification process. As a result, the photoelectric conversion efficiency of FAPbI3 perovskite quantum dot solar cells (PQDSCs) increased from 11.23 to 12.97% with an open-circuit voltage of 1.09 V, a short-circuit current density of 16.37 mA cm-2, and a filling factor of 72.13%. Furthermore, the stability of the device modified by amino acids retains over 80% of the initial efficiency upon being exposed to 20-30% relative humidity for 240 h of aging treatment. This work may offer an innovative concept and approach for surface ligand treatment to improve the photovoltaic performance of PQDSCs toward large-scale manufacture.

Solid-Phase Synthesis of Caged Luminescent Peptides via Side Chain Anchoring.

The synthesis of caged luminescent peptide substrates remains challenging, especially when libraries of the substrates are required. Most currently available synthetic methods rely on a solution-phase approach, which is less suited for parallel synthesis purposes. We herein present a solid-phase peptide synthesis (SPPS) method for the synthesis of caged aminoluciferin peptides via side chain anchoring of the P1 residue. After the synthesis of a preliminary test library consisting of 40 compounds, the synthetic method was validated and optimized for up to >100 g of resin. Subsequently, two separate larger peptide libraries were synthesized either having a P1 = lysine or arginine residue containing in total 719 novel peptide substrates. The use of a more stable caged nitrile precursor instead of caged aminoluciferin rendered our parallel synthetic approach completely suitable for SPPS and serine protease profiling was demonstrated using late-stage aminoluciferin generation.

Amplifying bactericidal activity: Surfactant-mediated AgBr thin film coating over two-dimensional vertically aligned ZnO nanorods for dark-light dual mode disinfection

Thin film coatings with potent antibacterial properties find critical applications in diverse domains such as medical devices, frequently touched surfaces, and food packaging for combating microbial proliferation across diverse scenarios. Two-dimensional photocatalytic antimicrobial coatings, offering a substantial actual-to-apparent surface ratio, hold immense potential for achieving this objective. However, realizing antibacterial performance not just under light but also in dark conditions remains a challenge. To address this, we present AgBr-coated vertically aligned ZnO nanorods (NRs) thin film architecture, employing a unique surfactant-mediated solution-phase spin-coating approach for achieving uniform deposition of AgBr onto ZnO NRs. The resulting ZnO NRs/AgBr heterojunction architectures have been characterized for their microstructural, morphological, elemental, optical, and wettability attributes. The studies have ascertained the tunability of AgBr content by modulating the concentration of its surfactant-based precursor solution. Further, valence band (VB) analyses revealed an increase in the electron density near to the VB edge. The dual role of AgBr as an antimicrobial agent and a photosensitizer, effectively enhancing the visible-light photodisinfection efficacy of ZnO NRs, has been evident through the dark-light dual mode antibacterial studies. Electron paramagnetic resonance measurements have shown hydroxyl radicals being majorly responsible for the visible-light photodisinfection performance. Encouragingly, reusability assessments showcase significant promise, while artificial sweat-wiping studies on the structures unveil heightened photodisinfection efficacy. This enhancement could be attributed to components like urea and lactic acid, speculated to augment the photocatalytic efficiency by minimizing charge recombination.

Scalable Synthesis of Selenide Solid-State Electrolytes for Sodium-Ion Batteries.

Solid-state sodium-ion batteries employing superionic solid-state electrolytes (SSEs) offer low manufacturing costs and improved safety and are considered to be a promising alternative to current Li-ion batteries. Solid-state electrolytes must have high chemical/electrochemical stability and superior ionic conductivity. In this work, we employed precursor and solvent engineering to design scalable and cost-efficient solution routes to produce air-stable sodium selenoantimonate (Na3SbSe4). First, a simple metathesis route is demonstrated for the production of the Sb2Se3 precursor that is subsequently used to form ternary Na3SbSe4 through two different routes: alcohol-mediated redox and alkahest amine-thiol approaches. In the former, the electrolyte was successfully synthesized in EtOH by using a similar redox solution coupled with Sb2Se3, Se, and NaOH as a basic reagent. In the alkahest approach, an amine-thiol solvent mixture is utilized for the dissolution of elemental Se and Na and further reaction with the binary precursor to obtain Na3SbSe4. Both routes produced electrolytes with room temperature ionic conductivity (∼0.2 mS cm-1) on par with reported performance from other conventional thermo-mechanical routes. These novel solution-phase approaches showcase the diversity and application of wet chemistry in producing selenide-based electrolytes for all-solid-state sodium batteries.

Synthesis and Post-Processing of Chemically Homogeneous Nanothreads from 2,5-Furandicarboxylic Acid.

Compared with conventional, solution-phase approaches, solid-state reaction methods can provide unique access to novel synthetic targets. Nanothreads-one-dimensional diamondoid polymers formed through the compression of small molecules-represent a new class of materials produced via solid-state reactions, however, the formation of chemically homogeneous products with targeted functionalization represents a persistent challenge. Through careful consideration of molecular precursor stacking geometry and functionalization, we report here the scalable synthesis of chemically homogeneous, functionalized nanothreads through the solid-state polymerization of 2,5-furandicarboxylic acid. The resulting product possesses high-density, pendant carboxyl functionalization along both sides of the backbone, enabling new opportunities for the post-synthetic processing and chemical modification of nanothread materials applicable to a broad range of potential applications.

Strategies and tactics for the synthesis of lipid I and II and shortened analogues: functional building blocks of bacterial cell wall biosynthesis.

Covering: the literature up to 2022This study discusses various synthetic strategies for the synthesis of lipid II, the pivotal bacterial cell wall precursor. In detail, it examines different solution phase approaches, reviews various solid phase sequences, and evaluates enzymatic ventures. The underlying rationale, scope, limitations, and perspectives of these strategies are discussed. The focus is on the tactics and strategies towards the authentic peptidoglycan compound, as well as analogues thereof with shortened side chains, which are increasingly recognized as more beneficial surrogates with more favorable physicochemical properties.

Heterointerface promoted trifunctional electrocatalysts for all temperature high-performance rechargeable Zn-air batteries.

The rational design of wide-temperature operating Zn-air batteries is crucial for their practical applications. However, the fundamental challenges remain; the limitation of the sluggish oxygen redox kinetics, insufficient active sites, and poor efficiency/cycle lifespan. Here we present heterointerface-promoted sulfur-deficient cobalt-tin-sulfur (CoS1-δ/SnS2-δ) trifunctional electrocatalysts by a facile solvothermal solution-phase approach. The CoS1-δ/SnS2-δ displays superb trifunctional activities, precisely a record-level oxygen bifunctional activity of 0.57 V (E1/2 = 0.90 V and Ej=10 = 1.47 V) and a hydrogen evolution overpotential (41 mV), outperforming those of Pt/C and RuO2. Theoretical calculations reveal the modulation of the electronic structures and d-band centers that endorse fast electron/proton transport for the hetero-interface and avoid the strong adsorption of intermediate species. The alkaline Zn-air batteries with CoS1-δ/SnS2-δ manifest record-high power density of 249 mW cm-2 and long-cycle life for >1000 cycles under harsh operations of 20 mA cm-2, surpassing those of Pt/C + RuO2 and previous state-of-the-art catalysts. Furthermore, the solid-state flexible Zn-air battery also displays remarkable performance with an energy density of 1077 Wh kg-1, >690 cycles for 50 mA cm-2, and a wide operating temperature from +80 to -40 °C with 85% capacity retention, which provides insights for practical Zn-air batteries.

Synthetic Studies with Bacitracin A and Preparation of Analogues Containing Alternative Zinc Binding Groups.

The growing threat of drug-resistant bacteria is a global concern, highlighting the urgent need for new antibiotics and antibacterial strategies. In this light, practical synthetic access to natural product antibiotics can provide important structure-activity insights while also opening avenues for the development of novel analogues with improved properties. To this end, we report an optimised synthetic route for the preparation of the clinically used macrocyclic peptide antibiotic bacitracin. Our combined solid- and solution-phase approach addresses the problematic, and previously unreported, formation of undesired epimers associated with the stereochemically fragile N-terminal thiazoline moiety. A number of bacitracin analogues were also prepared wherein the thiazoline motif was replaced by other known zinc-binding moieties and their antibacterial activities evaluated.

Solution phase growth and analysis of super-thin zigzag tin selenide nanoribbons

Tin selenide (SnSe), a highly promising layered material, has been garnering particular interest in recent times due to its significant promise for future energy devices. Herein we report a simple solution-phase approach for growing highly crystalline layered SnSe nanoribbons. Polyvinylpyrrolidone (PVP) was used as a templating agent to selectively passivates the (100) and (001) facets of the SnSe nanoribbons resulting in the unique growth of nanoribbons along their b-axis with a defined zigzag edge state along the sidewalls. The SnSe nanoribbons are few layers thick (∼20 layers), with mean widths of ∼40 nm, and achievable length of >1 μm. Nanoribbons could be produced in relatively high quantities (>150 mg) in a single batch experiment. The PVP coating also offers some resistance to oxidation, with the removal of the PVP seen to lead to the formation of a SnSe/SnO x core-shell structure. The use of non-toxic PVP to replace toxic amines that are typically employed for other 1D forms of SnSe is a significant advantage for sustainable and environmentally friendly applications. Heat transport properties of the SnSe nanoribbons, derived from power-dependent Raman spectroscopy, demonstrate the potential of SnSe nanoribbons as thermoelectric material.

Side-Chain Anchoring Strategies for the Synthesis of Peptide Thioesters and Selenoesters.

Peptides bearing C-terminal thioester and selenoester functionalities are essential precursors for the chemical synthesis of larger proteins using ligation chemistry, including native chemical ligation (NCL) and diselenide-selenoester ligation (DSL). The use of a side-chain anchoring thioesterification or selenoesterification approach offers a robust method to access peptide thioesters or peptide selenoesters in excellent yields and in high purity. Importantly, this methodology overcomes solubility issues and epimerization of the C-terminal amino acid residue that can occur using solution-phase approaches. Detailed methods for the solid-phase synthesis of peptide thioesters and selenoesters using a side-chain anchoring approach are outlined in this article.

Synthesis and Exon-Skipping Properties of a 3'-Ursodeoxycholic Acid-Conjugated Oligonucleotide Targeting DMD Pre-mRNA: Pre-Synthetic versus Post-Synthetic Approach.

Steric blocking antisense oligonucleotides (ASO) are promising tools for splice modulation such as exon-skipping, although their therapeutic effect may be compromised by insufficient delivery. To address this issue, we investigated the synthesis of a 20-mer 2′-OMe PS oligonucleotide conjugated at 3′-end with ursodeoxycholic acid (UDCA) involved in the targeting of human DMD exon 51, by exploiting both a pre-synthetic and a solution phase approach. The two approaches have been compared. Both strategies successfully provided the desired ASO 51 3′-UDC in good yield and purity. It should be pointed out that the pre-synthetic approach insured better yields and proved to be more cost-effective. The exon skipping efficiency of the conjugated oligonucleotide was evaluated in myogenic cell lines and compared to that of unconjugated one: a better performance was determined for ASO 51 3′-UDC with an average 9.5-fold increase with respect to ASO 51.

Developments in the Chemical Synthesis of Heparin and Heparan Sulfate.

Heparin and heparan sulfate represent key members of the glycosaminoglycan family of carbohydrates and underpin considerable repertoires of biological importance. As such, their efficiency of synthesis represents a key requirement, to further understand and exploit the H/HS structure-to-biological function axis. In this review we focus on chemical approaches to and methodology improvements for the synthesis of these essential sugars (from 2015 onwards). We first consider advances in accessing the heparin-derived pentasaccharide anticoagulant fondaparinux. This is followed by heparan sulfate targets, including key building block synthesis, oligosaccharide construction and chemical sulfation techniques. We end with a consideration of technological improvements to traditional, solution-phase synthesis approaches that are increasingly being utilised.

Ultrathin-shell epitaxial Ag@Au core-shell nanowires for high-performance and chemically-stable electronic, optical, and mechanical devices

Silver nanowires (AgNWs) hold great promise for applications in wearable electronics, flexible solar cells, chemical and biological sensors, photonic/plasmonic circuits, and scanning probe microscopy (SPM) due to their unique plasmonic, mechanical, and electronic properties. However, the lifetime, reliability, and operating conditions of AgNW-based devices are significantly restricted by their poor chemical stability, limiting their commercial potentials. Therefore, it is crucial to create a reliable oxidation barrier on AgNWs that provides long-term chemical stability to various optical, electrical, and mechanical devices while maintaining their high performance. Here we report a room-temperature solution-phase approach to grow an ultra-thin, epitaxial gold coating on AgNWs to effectively shield the Ag surface from environmental oxidation. The Ag@Au core-shell nanowires (Ag@Au NWs) remain stable in air for over six months, under elevated temperature and humidity (80 °C and 100% humidity) for twelve weeks, in physiological buffer solutions for three weeks, and can survive overnight treatment of an oxidative solution (2% H2O2). The Ag@Au core-shell NWs demonstrated comparable performance as pristine AgNWs in various electronic, optical, and mechanical devices, such as transparent mesh electrodes, surface-enhanced Raman spectroscopy (SERS) substrates, plasmonic waveguides, plasmonic nanofocusing probes, and high-aspect-ratio, high-resolution atomic force microscopy (AFM) probes. These Au@Ag core-shell NWs offer a universal solution towards chemically-stable AgNW-based devices without compromising material property or device performance.

Flow-based Methods in Chemical Peptide and Protein Synthesis.

Flow chemistry has emerged as a powerful method for on-demand chemical synthesis and modification of peptides and proteins. Herein, we discuss the characteristics of flow chemistry and how they are applied to various aspects of peptide chemistry. We highlight recent advances in automated flow-based peptide synthesis, which extend the length of peptides routinely accessible to single-domain proteins and allow for the collection of time-resolved synthesis data. Applications of this data for the prediction of synthesis outcome and the potential for the development of more sustainable synthesis methods are also discussed. Finally, we will review solutionphase approaches, including flow-based ligation strategies and peptide cyclization. Throughout this review, the current challenges and potential future developments are highlighted.

PEDOT-Coated Red Phosphorus Nanosphere Anodes for Pseudocapacitive Potassium-Ion Storage.

Potassium-ion batteries (KIBs) have come up as a potential alternative to lithium-ion batteries due to abundant potassium storage in the crust. Red phosphorus is a promising anode material for KIBs with abundant resources and high theoretical capacity. Nevertheless, large volume expansion, low electronic conductivity, and limited K+ charging speed in red phosphorus upon cycling have severely hindered the development of red phosphorus-based anodes. To obtain improved conductivity and structural stability, surface engineering of red phosphorus is required. Poly(3,4-ethylenedioxythiophene) (PEDOT)-coated red phosphorus nanospheres (RPNP@PEDOT) with an average diameter of 60 nm were synthesized via a facile solution-phase approach. PEDOT can relieve the volume change of red phosphorus and promote electron/ion transportation during charge−discharge cycles, which is partially corroborated by our DFT calculations. A specific capacity of 402 mAh g−1 at 0.1 A g−1 after 40 cycles, and a specific capacity of 302 mAh g−1 at 0.5 A g−1 after 275 cycles, were achieved by RPNP@PEDOT anode with a high pseudocapacitive contribution of 62%. The surface–interface engineering for the organic–inorganic composite of RPNP@PEDOT provides a novel perspective for broad applications of red phosphorus-based KIBs in fast charging occasions.