Preparation of (3-Aminopropyl)triethoxysilane-Modified Silica Particles with Tunable Isoelectric Point.

Silica particles modified with amino groups hold immense potential across diverse fields, owing to their distinctive properties. The widely adopted method of surface modification, utilizing (3-aminopropyl)triethoxysilane (APTES), facilitates the incorporation of amino-functional groups onto the silica surface, thereby creating sites for subsequent functionalization with other molecules. In this context, the ability to precisely tailor the surface properties of amino-functionalized silica particles is crucial for optimizing their performance in various applications. In this work, we systematically investigated the influence of the APTES concentration and water content on the density of amino groups grafted on the silica surface within an ethanol-water mixture. The rational control of hydrolysis and condensation of APTES enabled the precise regulation of the amino density on the silica surface, resulting in a notable shift in the isoelectric point from 2.9 to 9.2. Subsequently, we assembled amino-functionalized silica with different isoelectric points with gold nanoparticles to demonstrate their tunable ability as surface-enhanced Raman scattering (SERS) substrates. This controlled and tailored amino-functionalization process opens up new routes for fine-tuning the properties of silica particles, thereby expanding their utility across various applications in materials science, nanotechnology, and biomedicine.

Synthesis of Mesoporous Silica Using the Sol-Gel Approach: Adjusting Architecture and Composition for Novel Applications.

The sol-gel chemistry of silica has long been used for manipulating the size, shape, and microstructure of mesoporous silica particles. This manipulation is performed in mild conditions through controlling the hydrolysis and condensation of silicon alkoxide. Compared to amorphous silica particles, the preparation of mesoporous silica, such as MCM-41, using the sol-gel approach offers several unique advantages in the fields of catalysis, medicament, and environment, due to its ordered mesoporous structure, high specific surface area, large pore volume, and easily functionalized surface. In this review, our primary focus is on the latest research related to the manipulation of mesoporous silica architectures using the sol-gel approach. We summarize various structures, including hollow, yolk-shell, multi-shelled hollow, Janus, nanotubular, and 2D membrane structures. Additionally, we survey sol-gel strategies involving the introduction of various functional elements onto the surface of mesoporous silica to enhance its performance. Furthermore, we outline the prospects and challenges associated with mesoporous silica featuring different structures and functions in promising applications, such as high-performance catalysis, biomedicine, wastewater treatment, and CO2 capture.

Ultrafast photophysics of an orange-red thermally activated delayed fluorescence emitter: the role of external structural restraint.

The application of thermally activated delay fluorescence (TADF) emitters in the orange-red regime usually suffers from the fast non-radiative decay of emissive singlet states (kSNR), leading to low emitting efficiency in corresponding organic light-emitting diode (OLED) devices. Although kSNR has been quantitatively described by energy gap law, how ultrafast molecular motions are associated with the kSNR of TADF emitters remains largely unknown, which limits the development of new strategies for improving the emitting efficiency of corresponding OLED devices. In this work, we employed two commercial TADF emitters (TDBA-Ac and PzTDBA) as a model system and attempted to clarify the relationship between ultrafast excited-state structural relaxation (ES-SR) and kSNR. Spectroscopic and theoretical investigations indicated that S1/S0 ES-SR is directly associated with promoting vibrational modes, which are considerably involved in electronic-vibrational coupling through the Huang-Rhys factor, while kSNR is largely affected by the reorganization energy of the promoting modes. By restraining S1/S0 ES-SR in doping films, the kSNR of TADF emitters can be greatly reduced, resulting in high emitting efficiency. Therefore, by establishing the connection among S1/S0 ES-SR, promoting modes and kSNR of TADF emitters, our work clarified the key role of external structural restraint for achieving high emitting efficiency in TADF-based OLED devices.

Boosting Excited-State Energy Transfer by Anchoring Dipole Orientation in Binary Thermally Activated Delayed Fluorescence/J-Aggregate Assemblies.

Förster resonance energy transfer (FRET) has been widely applied in fluorescence imaging, sensing and so on, while developing useful strategy of boosting FRET efficiency becomes a key issue that limits the application. Except optimizing spectral properties, promoting orientation factor (κ2) has been well discussed but rarely utilized for boosting FRET. Herein, we constructed binary nano-assembling of two thermally activated delayed fluorescence (TADF) emitters (2CzPN and DMAC-DPS) with J-type aggregate of cyanine dye (C8S4) as doping films by taking advantage of their electrostatic interactions. Time-resolved spectroscopic measurements indicated that 2CzPN/Cy-J films exhibit an order of magnitude higher kFRET than DMAC-DPS/Cy-J films. Further quantitative analysing on kFRET and kDET indicated higher orientation factor (κ2) in 2CzPN/Cy-J films play a key role for achieving fast kFRET, which was subsequently confirmed by anisotropic measurements. Corresponding DFT/TDDFT calculation revealed strong "two-point" electrostatic anchoring in 2CzPN/Cy-J films that is responsible for highly orientated transitions. We provide a new strategy for boosting FRET in nano-assemblies, which might be inspired for designing FRET-based devices of sensing, imaging and information encryption.

Red Carbon Mediated Formation of Cu2O Clusters Dispersed on the Oxocarbon Framework by Fehling's Route and their Use for the Nitrate Electroreduction in Acidic Conditions.

The oligomers of carbon suboxide, known as red carbon, exhibit a highly conjugated structure and semiconducting properties. Upon mild heat treatment, it transforms into a carbonaceous framework rich in oxygen surface terminations, called oxocarbon. In this study, the abundant oxygen functionalities are harnessed as anchors to create oxocarbon-supported nanohybrid electrocatalysts. Starting with single atomic Cu (II) strongly coordinated to oxygen atoms on red carbon, the Fehling reaction leads to the formation of Cu2O clusters. Simultaneously, a covalent oxocarbon framework emerges via cross-linking, providing robust support for Cu2O clusters. Notably, the oxocarbon support effectively stabilizes Cu2O clusters of very small size, ensuring their high durability in acidic conditions and the presence of ammonia. The synthesized material exhibits a superior electrocatalytic activity for nitrate reduction under acidic electrolyte conditions, with a high yield rate of ammonium (NH4 +) at 3.31 mmol h-1 mgcat -1 and a Faradaic efficiency of 92.5% at a potential of -0.4 V (vs RHE).

Monodispersed, Micron-Sized Supermicroporous Silica Particles by Cetyltrimethylammonium Bromide-Mediated Preparation.

In this study, we present a novel modified Stöber method utilizing cetyltrimethylammonium bromide (CTAB) as a mediator for the preparation of monodispersed, micron-sized supermicroporous silica particles. Observed results show prepared silica particles ranging in size from 0.64 to 1.36 µm with an increase in CTAB concentration from 1.0 to 5.0 mM. The particles exhibited low polydispersity (<5%), a high Brunauer-Emmett-Teller surface area (570 to 1064 m2/g), and pore volumes ranging from 0.22 to 0.39 cm3/g. The pore size, determined using the Barrett-Joyner-Halenda method from the adsorption branches of the isotherms, was approximately 1.9 nm, specifically 1.83, 1.85, and 1.90 nm, as the CTAB concentration increased from 1.0 to 2.5 and 5.0 mM, respectively. The resulting particles displayed a narrow distribution of pore diameters. In addition, to obtain an in-depth understanding of the role of CTAB on the preparation of silica particles, a possible mechanism is also investigated using conductivity, dynamic light scattering (DLS), zeta potential, FT-IR spectra, and transmission electron microscopy. Our findings demonstrate that CTAB plays multiple roles in the hydrolysis/condensation of TEOS (tetraethyl orthosilicate) and subsequent nucleation and growth of silica particles. CTAB acts as a template for superporosity, a stabilizer for colloids, and an accelerator for nucleation and growth, leading to formation of monodispersed micrometer silica particles. Further characterization through FT-IR and 29Si solid NMR spectra revealed that the micron silica particles were obtained with inhomogeneity in the condensation degree, allowing for selective etching through hot incubation to form micron-sized hollow silica spheres.

Influence of maxillary molar distalization with clear aligners on three-dimensional direction: molar distal movement, intrusion, distal tip and crown buccal torque.

BACKGROUND: The aim of this study was to evaluate the distal movement, vertical movement, distal tipping and crown buccal torque of maxillary molars after the completion of distalization by comparing the predicted movement with the achieved movement using palatal rugae registration. METHODS: The study included 22 clear aligner patients (7 males and 15 females), and 79 molars were measured. Two digital models were generated before treatment and after molar distalization and were superimposed after selecting the palatal rugae area for registration in GOM inspect suite software 2022 (GOM; Braunschweig, Germany). The predicted and achieved movements of molar distalization, intrusion, distal tip and crown buccal torque were measured and compared. RESULT: The achieved distalization (1.25 ± 0.79 mm vs. 2.17 ± 1.03 mm, P < 0.001; 1.41 ± 1.00 mm vs. 2.66 ± 1.15 mm, P < 0.001), intrusion (0.47 ± 0.41 mm vs. 0.18 ± 0.54 mm, P < 0.01; 0.58 ± 0.65 mm vs. 0.10 ± 1.12 mm, P < 0.01), distal tip (5.30 ± 4.56° vs. 1.53 ± 2.55°, P < 0.001; 4.87 ± 4.50° vs. - 1.95 ± 4.32°, P < 0.001) and crown buccal torque (1.95 ± 4.18° vs. - 1.15 ± 4.75°, P < 0.001; 0.43 ± 4.39° vs. - 4.27 ± 6.42°, P < 0.001) were significantly different from the predicted values in the two groups (first molar, second molar). Significant regression relationships were found between the achieved distal movement and deviational intrusion (R2 = 0.203, P < 0.0001), distal tip (R2 = 0.133, P < 0.001) and crown buccal torque (R2 = 0.067, P < 0.05). There was a significant correlation between the deviational movements of intrusion and the distal tip (R = 0.555, P < 0.0001). CONCLUSION: Approximately 2 mm maxillary molar distalization was achieved in this study. Deviational movement of intrusion, distal tip and crown buccal torque beyond the clear aligner virtual design appeared to a certain degree after distalization. Thus, more attention should be given to molar intrusion and distal tip and crown buccal torque as the designed distalization increases.

Resolving the Photophysics of Nitrogen-Embedded Multiple Resonance Emitters: Origin of Color Purity and Emitting Efficiency.

The emerging nitrogen-embedded multiple resonance (MR) emitters with an indolo[3,2,1-jk] carbazole (ICz) unit have exhibited promising performance for high-resolution organic light-emitting diode (OLED) devices, while the underlying photophysics has been rarely reported. In this work, the optical spectra, color purity, and emitting efficiency of ICz-based MR emitters were investigated by using electronic structure and thermal vibration correlation function (TVCF) calculations. Unlike B-N MR emitters, the high color purity of investigated ICz-based MR emitters was mainly contributed by considerable structural rigidity, which also greatly affects the radiative decay rate and fluorescence quantum yield of the S1 state. For the majority of investigated emitters, potential reverse intersystem crossing (RISC) channels (T1 → S1 and T2 → S1) are limited by thermally inaccessible ΔEST* or insufficient spin-orbital coupling (SOC), which can be distinguished by the calculated temperature-dependent RISC rate pattern. We provided a systematic photophysical picture for ICz-based MR emitters that might be interesting for the OLED design and application community.

Orthodontic care in orthodontic patients during the COVID-2019 pandemic: emergency, emergency response and orthodontic treatment preference.

BACKGROUND: The objective of this study was to investigate the characteristics of emergencies and the requirement for emergency treatment after the suspension of orthodontic appointments. The attitude towards orthodontic treatment preference was evaluated as well, including receiving orthodontic treatment and the preference for orthodontic appliances. SUBJECTS AND METHODS: An electronic questionnaire was distributed to the patients, including 4 sections: Section 1 - demographic and basic information; Section 2 - the characteristics of emergencies and emergency treatment requirements; Section 3 - the NRS-11 for pain and Manchester Orofacial Pain Disability Scale used to evaluate the intensity of orofacial pain and disability; and Section 4 - attitudes towards receiving orthodontic treatment and appliance preference. Descriptive statistics, Pearson's chi-square test, Wilcoxon's rank-sum test and stepwise generalized linear model (GLM) were performed with significance set at P < 0.05. RESULT: Most participants' (91.61%) follow-up appointments were suspended. The emergency rate and emergency treatment requirements were not different between the fixed appliance (FA) and clear aligner (CA) groups. Patients who reported emergencies (P < 0.01) in the FA group (P < 0.05) and some emergencies in the FA (P < 0.05) suffered worse pain and disability. More FA participants preferred alternative appliances (P < 0.05) due to pain and disability (P < 0.05). CONCLUSION: FA patients' emergencies caused worse pain and disability when orthodontic appointments were suspended. Pain and disability were not the causes of emergency treatment requirements. The CA group seemed to show a tendency towards orthodontic appliance preference, which was an ideal modality to weather the epidemic, combined with telemedicine.

Au (III) cross-linked hollow organosilica capsules from 3-aminopropyltriethoxysilane.

Hollow organosilica capsules have received extensive interest due to their application potentials in catalyst, sensor, drug delivery etc. In this work, we demonstrate a novel strategy to fabricate hollow organosilica capsules based on coordination interaction, by using 3-aminopropyltriethoxysilane (APTES) as precursor and Au (III) as cross-linker. In this approach, stable APTES droplets are first formed in water with the presence of Au (III) due to the coordination effect between Au (III) and the amino groups of APTES located on the surface of the droplets. Subsequently, the self-catalyzed hydrolysis/condensation of APTES allows for the formation of hollow organosilica capsules, in which the droplets of APTES themselves act as soft template and the Au (III) as cross-linker. The formation mechanism of the capsules was investigated, and potential of the as-prepared Au (III) cross-linked hollow organosilica capsules as glutathione (GSH) sensitive drug carriers was evaluated. In addition, Au particle embedded hollow capsules are further obtained by in-situ reduction of the Au (III) in the shell, which showed excellent stability towards the cyclic catalytic reductions of p-nitroaniline.

Intrinsic Optical Properties and Emerging Applications of Gold Nanostructures.

The collective oscillation of free electrons at the nanoscale surface of gold nanostructures is closely modulated by tuning the size, shape/morphology, phase, composition, hybridization, assembly, and nanopatterning, along with the surroundings of the plasmonic surface located at a dielectric interface with air, liquid, and solid. This review first introduces the physical origin of the intrinsic optical properties of gold nanostructures and further summarizes stimuli-responsive changes in optical properties, metal-field-enhanced optical signals, luminescence spectral shaping, chiroptical response, and photogenerated hot carriers. The current success in the landscape of nanoscience and nanotechnology mainly originates from the abundant optical properties of gold nanostructures in the thermodynamically stable face-centered cubic (fcc) phase. It has been further extended by crystal phase engineering to prepare thermodynamically unfavorable phases (e.g., kinetically stable) and heterophases to modulate their intriguing phase-dependent optical properties. A broad range of promising applications, including but not limited to full-color displays, solar energy harvesting, photochemical reactions, optical sensing, and microscopic/biomedical imaging, have fostered parallel research on the multitude of physical effects occurring in gold nanostructures.

Swellable hollow periodic mesoporous organosilica capsules with ultrahigh loading capacity for hydrophobic drugs.

As a new kind of drug carrier, practical applications of hollow periodic mesoporous organosilica (HPMO) have been greatly limited by their low loading capacity for hydrophobic drugs. In this work, we demonstrated the preparation of HPMO capsules with tunable shell thickness by using 1,2-bis(triethoxysilyl)ethane as the precursor. The capsules with thin shells and thus low Young's modulus showed excellent swellability to organic solvents containing hydrophobic drugs. As a result, hydrophobic drugs, i.e., paclitaxel (PTX) could be loaded into the hollow interior of the HPMO capsules with 4 nm shell at an efficiency of ca. 120 %. The as-prepared PTX-loaded HPMO capsules were dispersible in aqueous media and showed improved performance in killing cancer cells compared to free PTX.

ICG@ZIF-8/PDA/Ag composites as chemo-photothermal antibacterial agents for efficient sterilization and enhanced wound disinfection.

Bacterial infection has increasingly affected people's lives, therefore it is significant to explore novel antibacterial agents and strategies for efficient disinfection. Herein, we designed ZIF-8 based composites ICG@ZIF-8/PDA/Ag, which encapsulate photothermal agent indocyanine green (ICG) and grow polydopamine (PDA) on their surface for in situ reduction to generate Ag nanoparticles. With 20 min of 808 nm laser irradiation at 1.5 W cm-2, 100 µg mL-1 ICG@ZIF-8/PDA/Ag exhibited 100% bactericidal effects toward E. coli and S. aureus bacteria resulting from both hyperthermia of ICG and PDA and chemical toxicity of the released Ag and Zn ions. When the bacterial incubation period was extended to 12 h, the minimum bactericidal concentration (MBC) of ICG@ZIF-8/PDA/Ag was reduced to 6.25 µg mL-1, and this extremely low MBC was due to the long-term chemo-photothermal combinational effect induced by NIR irradiation. Additionally, the composites successfully promote the healing of S. aureus infected wounds on mice. This work constructed photo-responsive antibacterial composites that realize chemo-photothermal synergistic therapy.

Au Nanoflowers for Catalyzing and In Situ Surface-Enhanced Raman Spectroscopy Monitoring of the Dimerization of p-Aminothiophenol.

In this work, we demonstrated a facile approach for fabrication of Au nanoflowers (Au NFs) using an amino-containing organosilane, 3-aminopropyltriethoxysilane (APTES), as a shape-directing agent. In this approach, the morphology of the Au particles evolved from sphere-like to flower-like with increasing the concentration of APTES, accompanied by a red shift in the localized surface plasmon resonance peak from 520 to 685 nm. It was identified that the addition of APTES is profitable to direct the preferential growth of the (111) plane of face-centered cubic gold and promote the formation of anisotropic Au NFs. The as-prepared Au NFs, with APTES on their surface, presented effective catalytic and surface-enhanced Raman scattering (SERS) performances, as evidenced by their applications in catalyzing the dimerization of p-aminothiophenol and monitoring the reaction process via in situ SERS analysis.

Fabrication of Bovine Serum Albumin@Au Particles for Colorimetric Detection of Glutathione.

Abnormal concentrations of glutathione (GSH) are important indicators of many human diseases such as cancers, liver damage, AIDS, and Alzheimer's disease. In this work, a kind of bovine serum albumin (BSA)@Au core-shell particles were fabricated using 110 nm BSA aggregates as a template, onto which gold shells composed of Au nanoparticles (NPs) were grown through a seeded growth approach. The morphology of the Au shells deposited on BSA aggregates was tuned from sparse to dense distribution of Au NPs by increasing the concentration of silver ions contained in the growth solutions. Surface plasmon resonance (SPR) peaks of BSA@Au particles were tunable in the range from 550 to 620 nm, corresponding to evolution in color from red to blue due to the enhanced plasmonic coupling among the Au NPs in the shell. The blue BSA@Au particles were qualified for colorimetric detection of GSH since GSH may act as a swelling agent for BSA@Au particles by breaking the intermolecular disulfide bonds in BSA aggregates. With an increased amount of GSH presented, the color of BSA@Au particles evolved from blue to red attributed to gradual swelling of BSA@Au particles and thus increased the distance among the Au NPs in the shell, which was readily recognized by naked eyes or recorded by ultraviolet-visible (UV-vis) spectroscopy. This colorimetric method exhibited good selectivity and anti-interference capability in the analysis of GSH in real samples. In addition, a solid sensing system for the detection of GSH was designed and fabricated by dispersing BSA@Au particles into an agarose hydrogel.

Bovine serum albumin assisted preparation of ultra-stable gold nanoflowers and their selective Raman response to charged dyes.

In this work, we demonstrated a facile, one-pot approach for preparation of gold nanoflowers by using tetrachloroauric acid as a gold precursor, ascorbic acid as a reductant, and bovine serum albumin (BSA) as a ligand. It was found that the morphology of the as-prepared gold nanoparticles (Au NPs) was dependent on the concentration of BSA introduced into the reaction solutions. It is identified that BSA directed the preferential growth along the 〈111〉 direction, which contributed to the anisotropic growth of Au NPs and thus the formation of Au nanoflowers. An increased concentration of BSA reduced the reactivity of the gold precursor, leading to the formation of Au nanoflowers with increased size, which could also be obtained by decreasing the amount of reductant added. The Au nanoflowers were ultra-stable in the presence of chloride ions under acidic pH, making them suitable for selective detection of oppositely charged dyes via surface-enhanced Raman scattering according to the isoelectric point (∼4.7) of BSA capped on their surface.

Unraveling the Growth Mechanism of Silica Particles in the Stöber Method: In Situ Seeded Growth Model.

In this work, we investigated the kinetic balance between ammonia-catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) and subsequent condensation over the growth of silica particles in the Stöber method. Our results reveal that, at the initial stage, the reaction is dictated by TEOS hydrolysis to form silanol monomers, which is denoted as pathway I and is responsible for nucleation and growth of small silica particles via condensation of neighboring silanol monomers and siloxane network clusters derived thereafter. Afterward, the reaction is dictated by condensation of newly formed silanol monomers onto the earlier formed silica particles, which is denoted as pathway II and is responsible for the enlargement in size of silica particles. When TEOS hydrolysis is significantly promoted, either at high ammonia concentration (≥0.95 M) or at low ammonia concentration in the presence of LiOH as secondary catalyst, temporal separation of pathways I and II makes the Stöber method reminiscent of in situ seeded growth. This knowledge advance enables us not only to reconcile the most prevailing aggregation-only and monomer-addition models in literature into one consistent framework to interpret the Stöber process but also to grow monodisperse silica particles with sizes in the range 15-230 nm simply but precisely regulated by the ammonia concentration with the aid of LiOH.