Loading Determination of DMTr-substituted Resins for Large-scale Oligonucleotide Synthesis.

The loading (i.e., substitution) of solid supports for oligonucleotide synthesis is an important parameter in large-scale manufacturing of oligonucleotides. Several key process parameters are dependent on the substitution of the solid support, including the number of phosphoramidite nucleoside equivalents used in the coupling step. For dimethoxytrityl (DMTr)-loaded solid supports, the substitution of the resin is determined by quantitatively cleaving the DMTr protecting group from the resin under acidic conditions and then analyzing the DMTr cation extinction by UV/vis spectroscopy. The spectrometric measurement can be performed at 409 nm or the global extinction maximum of 510 nm. The substitution is then calculated based on the Lambert-Beer law analogously to the substitution determination of Fmoc-substituted resins. Below, the determination of the molar extinction coefficient at 510 nm in a solution of 10% dichloroacetic acid in toluene and subsequent determination of the DMTr loading of DMTr-substituted resins is reported. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Determination of the molar extinction coefficient at 510 nm in DCA Deblock solution Basic Protocol 2: Substitution determination of DMTr-substituted resins by cleavage of the DMTr cation.

Comparative evaluation on wear resistance of metal sleeve, sleeve-free resin, and reinforced sleeve-free resin implant guide: An in vitro study.

BACKGROUND: In-office three-dimensional (3D) printers and metal sleeveless surgical guides are becoming a major trend recently. However, metal sleeve-free designs are reported to be more prone to distortion which might lead to variation in the inner diameter of the drill hole and cause deviation and inaccuracy in the placement of the implant. Carbon fiber nanoparticles are reported to improve the properties of 3D printing resin material in industrial application. AIM: The purpose of the study is to evaluate and compare the wear resistance of 3D-printed implant guides with metal sleeve, sleeve-free, and reinforced sleeve-free resin to the guide drill. MATERIALS AND METHODS: A total of 66 samples with 22 samples in each group. Three groups including 3D-printed surgical guide with metal sleeve (Group A), without metal sleeve (Group B), an carbon fiber reinforced without metal sleeve (Group C) were included in the study. All samples were evaluated before sequential drilling and after sequential drilling using Vision Measuring Machine. The data were tabulated and statistically evaluated. RESULTS: The data obtained were statistically analyzed with one-way analysis of variance and posthoc test. The data obtained for wear observed in the samples showed that the wear was highest in Group B with a mean of 0.5036 ± 0.1118 and the least was observed in Group A with a mean of 0.0228 ± 0.0154 and Group C was almost similar to Group A with mean of 0.0710 ± 0.0381. The results showed there was a significant difference between Group B with Group A and C, respectively (P < 0.05). The results showed that there was no significant difference regarding the wear observed between Groups A and C (P > 0.05). CONCLUSION: The wear observed in the guide with a metal sleeve and carbon fiber reinforced without a metal sleeve was almost similar. The carbon fiber-reinforced guide showed better tolerance to guide drill equivalent to metal sleeve. Thus, carbon fiber nanoparticles reinforced in 3D printing resin have shown improved strength and can be used as a good replacement for a metal sleeve for an accurate placement of the implant.

Effects of washing agents on the mechanical and biocompatibility properties of water-washable 3D printing crown and bridge resin.

Three-dimensional (3D) printing, otherwise known as additive manufacturing in a non-technical context, is becoming increasingly popular in the field of dentistry. As an essential step in the 3D printing process, postwashing with organic solvents can damage the printed resin polymer and possibly pose a risk to human health. The development of water-washable dental resins means that water can be used as a washing agent. However, the effects of washing agents and washing times on the mechanical and biocompatibility properties of water-washable resins remain unclear. This study investigated the impact of different washing agents (water, detergent, and alcohol) and washing time points (5, 10, 20, and 30 min) on the flexural strength, Vickers hardness, surface characterization, degree of conversion, biocompatibility, and monomer elution of 3D printed samples. Using water for long-term washing better preserved the mechanical properties, caused a smooth surface, and improved the degree of conversion, with 20 min of washing with water achieving the same biological performance as organic solvents. Water is an applicable agent option for washing the 3D printing water-washable temporary crown and bridge resin in the postwashing process. This advancement facilitates the development of other water-washable intraoral resins and the optimization of clinical standard washing guidelines.

Adsorption and desorption characteristics of flavonoids from white tea using macroporous adsorption resin.

White tea contains the highest flavonoids compared to other teas. While there have been numerous studies on the components of different tea varieties, research explicitly focusing on the flavonoid content of white tea remains scarce, making the need for a good flavonoid purification process for white tea even more important. This study compared the adsorption and desorption performance of five types of macroporous resins: D101, HP20, HPD500, DM301, and AB-8. Among the tested resins, AB-8 was selected based on its best adsorption and desorption performance to investigate the static adsorption kinetics and dynamic adsorption-desorption purification of white tea flavonoids. The optimal purification process was determined: adsorption temperature 25 °C, crude tea flavonoid extract pH 3, ethanol concentration 80 %, sample loading flow rate and eluent flow rate 1.5 BV/min, and eluent dosage 40 BV. The results indicated that the adsorption process followed pseudo-second-order kinetics. Under the above purification conditions, the purity of the total flavonoids in the purified white tea flavonoid increased from approximately 17.69 to 46.23 %, achieving a 2.61-fold improvement, indicating good purification results. The purified white tea flavonoid can be further used for nutraceutical and pharmaceutical applications.

Separation of Flavonoids and Purification of Chlorogenic Acid from Bamboo Leaves Extraction Residues by Combination of Macroporous Resin and High-Speed Counter-Current Chromatography.

Flavonoids are major active small-molecule compounds in bamboo leaves, which can be easily obtained from the bamboo leaves extraction residues (BLER) after the polysaccharides extraction. Six macroporous resins with different properties were screened to prepare and enrich isoorientin (IOR), orientin (OR), vitexin (VI), and isovitexin (IVI) from BLER, and the XAD-7HP resin with the best adsorption and desorption performance was selected for further evaluation. Based on the static adsorption experiments, the experimental results showed that the adsorption isotherm fitted well with the Langmuir isotherm model, and the adsorption process was better explained by the pseudo-second-order kinetic model. After the dynamic trial of resin column chromatography, 20 bed volume (BV) of upload sample and 60% ethanol as eluting solvent was used in a lab scale-up separation, and the results demonstrated that the content of four flavonoids could be increased by 4.5-fold, with recoveries between 72.86 and 88.21%. In addition, chlorogenic acid (CA) with purity of 95.1% was obtained in water-eluted parts during dynamic resin separation and further purified by high-speed countercurrent chromatography (HSCCC). In conclusion, this rapid and efficient method can provide a reference to utilize BLER to produce high-value-added food and pharmaceutical products.

Preparation of a fluorinated dental resin system and its anti-adhesive properties against S. mutans.

OBJECTIVES: The purpose of this study was to characterize physicochemical properties and investigate anti-bacterial adhesion effect of dental resins containing fluorinated monomers. METHOD: Fluorinated dimethacrylate FDMA was mixed with commonly used reactive diluent triethylene- glycol dimethacrylate (TEGDMA) and fluorinated diluent 1 H,1 H-heptafluorobutyl methacrylate (FBMA) separately at a mass ratio of 60 wt./40 wt. to prepare fluorinated resin systems. Double bond conversion (DC), flexural strength (FS) and modulus (FM), water sorption (WS) and solubility (SL), contact angle and surface free energy, surface element concentration, and anti-adhesion effect against Streptococcus mutans (S. mutans) were investigated according to standard or referenced methods. 2,2-bis[4-(2-hydroxy-3-methacryloy-loxypropyl)-phenyl]propane (Bis-GMA)/TEGDMA (60/40, wt./wt.) was used as control. RESULTS: Both fluorinated resin systems had higher DC than Bis-GMA based resin (p < 0.05); compared with Bis-GMA based resin (FS, FDMA/TEGDMA resin system had higher FS (p < 0.05) and comparable FM (p > 0.05), while FDMA/FBMA resins system had lower FS and FM (p < 0.05). Both fluorinated resin systems had lower WS and SL than Bis-GMA based resin (p < 0.05), and FDMA/TEGDMA resin system had the lowest WS (p < 0.05) in all experimental resin systems. Only FDMA/FBMA resin system showed lower surface free energy than Bis-GMA based resin (p < 0.05). When the surface was smooth, FDMA/FBMA resin system had lower amount of adherent S. mutans than Bis-GMA based resin (p < 0.05), while after the surface became roughness, FDMA/FBMA resin system had comparable amount of adherent S. mutans as Bis-GMA based resin (p > 0.05). SIGNIFICANCE: Resin system prepared exclusively with fluorinated methacrylate monomers reduced the S. mutans adhesion due to their increased hydrophobicity and decreased surface energy., while flexural properties of it should be improved.

BNN/TiO2 nanocomposite system-modified dental flow resins and the mechanism of the enhancement of mechanical and antibacterial properties.

Robust and antibacterial dental resins are essential for repairing the shape and function of the teeth. However, an ingenious way to achieve a synergistic enhancement of these two properties is still lacking. In this work, guided by molecular dynamics (MD) calculations, a boron nitride nanosheet (BNN)/titanium dioxide (TiO2) nanocomposite system was synthesized and used to modify the dental flow resin to enhance its mechanical and antimicrobial properties. The mechanical and antimicrobial enhancement mechanisms were further explored. The modified resin demonstrated outstanding performance improvement with 88.23%, 58.47%, 82.01%, and 55.06% improvement in compressive strength (CS), microhardness (MH), flexural strength (FS), and elastic modulus (EM), respectively. Moreover, the modified resin could effectively inhibit the growth of Streptococcus mutans (S. mutans) regardless of aging in water and the inhibition rates were more than 90%. In conclusion, the modified resin is expected to be an ideal restorative material for clinical applications.

An Effective Chromatography Process for Simultaneous Purification and Separation of Total Lignans and Flavonoids from Valeriana amurensis.

An effective chromatography process was developed and validated for simultaneous purification and separation of total lignans and flavonoids from Valeriana amurensis. The total lignans and flavonoids in Valeriana amurensis extract were prepurified with macroporous resin column chromatography, and the conditions were optimized as follows: 40 mg/mL Valeriana amurensis extract (2.0 g) solution was loaded onto an AB-8 resin column with a diameter-to-height ratio of 1:7, followed by adsorption for 6 h; then, the column was eluted successively with 5 BV water and 10% and 50% ethanol at a flow rate 2 BV/h. The obtained 50% ethanol fraction was further repurified and separated by polyamide resin column chromatography to obtain the total lignans and flavonoids, respectively. The chromatography conditions were optimized as follows: a 50% ethanol fraction (1.0 g) was mixed with 1.0 g polyamide resin and loaded onto a polyamide resin (60-100 mesh) column with a diameter-to-height ratio of 1:3; then, the column was eluted successively with 6 BV water and 40% and 80% ethanol at a flow rate of 4 BV/h. The total lignans and flavonoids were obtained from water and 80% ethanol fraction, respectively. The content and recovery of standard compounds in total lignans and flavonoids were analyzed with HPLC-PDA, and the feasibility of the process was confirmed.

Impact of curcumin loading on the physicochemical, mechanical and antimicrobial properties of a methacrylate-based experimental dental resin.

Oral biofilms are directly linked to one of the most common chronic human diseases, dental caries. Resin-based dental materials have significant potential to replace amalgam, however they lack sufficient antimicrobial power. This innovative study investigates a curcumin-loaded dental resin which can be utilized in an antimicrobial photodynamic therapy (aPDT) approach. The study evaluated the effects of curcumin loading on resin physicochemical, mechanical, and adhesive properties, as well as the antimicrobial response associated with blue light activation. Preliminary tests involving degree of conversion (DC) and sample integrity determined the optimal loading of curcumin to be restricted to 0.05 and 0.10 wt%. These optimal loadings were tested for flexural strength (FS), water sorption (WS) and solubility (SL), shear bond strength to dentin (SBS), and viability of Streptococcus mutans under 14.6 J/cm2 blue light or dark conditions, in 6 h and 24 h biofilms. The results demonstrated that 0.10 wt% curcumin had minimal impact on either FS or SBS, but detectably increased WS and SL. A 2 log10 (CFU/mL) reduction in S. mutans after light application in both 6 h and 24 h biofilms were corroborated by CLSM imaging and highlighted the significant potential of this novel aPDT approach with resin-based dental materials.

Physical and mechanical properties of a dental resin adhesive containing hydrophobic chitin nanocrystals.

OBJECTIVES: In this paper we propose embedding natural fillers, such as pristine and functionalized chitin nanocrystals, into resin adhesives to produce photopolymerizable dental filled adhesives with enhanced biocompatibility, hydrophobicity, mechanical resistance, and anti-bacterial properties. METHODS: Chitin nanocrystals (ChNC) were functionalized with decanoyl chloride and methacrylic anhydride to produce ChNC-C10 and ChNC-MA, respectively. These hydrophobically functionalized chitin nanocrystals were incorporated into a resin adhesive at concentrations of 0.5-3.0 wt% to assess the materials' physical and mechanical properties through Fourier-transform infrared (FTIR) spectroscopy, solid-state NMR spectroscopy, X-ray diffraction (XRD), elemental analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), flexural strength, microhardness, and water sorption tests. RESULTS: The analytical techniques confirmed the successful preparation of chitin nanocrystals from commercial chitin powder derived from shrimp shells and the efficient hydrophobization of their surface. Electron microscope images indicated that the increased hydrophobicity of ChNC-C10 promotes the formation of layered structures throughout the resin adhesive, while ChNC-MA tends to form aggregates in the matrix. Adhesives filled with ChNC-C10 enhanced their flexural strength, microhardness, and thermal stability and decreased their water sorption and degree of conversion. Adhesives filled with ChNC-MA resulted in improvements in microhardness, in water sorption and degree of conversion, although they did not exhibit augmentation of their flexural strength and thermal stability. SIGNIFICANCE: In light of the improved physical and mechanical properties with respect to the control, resin adhesives filled with anti-bacterial chitin nanocrystals are promising new materials for dental applications, especially those filled with low/moderate amounts of ChNC-C10.

Preparation of Bis-GMA free dental resin composites with anti-adhesion effect against Streptococcus mutans using synthesized fluorine-containing methacrylate (DFMA).

With purpose of preparing Bis-GMA free dental resin composites (DRCs) with anti-adhesion effect against Streptococcus mutans (S. mutans), a new fluorinated dimethacrylate (DFMA) was synthesized and used as base resin of DRCs. Two reactive diluents TEGDMA and SR833s were mixed with DFMA separately to prepare resin matrixes. After mixing with inorganic fillers, two DFMA based DRCs were obtained and named as DT (DFMA/TEGDMA) and DS (DFMA/SR833s) according to the resin matrix composition. Bis-GMA based DRC (BT) was used as control. The double bond conversion (DC), bacteria adhesion, mucin adsorption, contact angle, surface free energy, volumetric shrinkage (VS), shrinkage stress (SS), water sorption (WS) and solubility (SL), flexural strength (FS) and modulus (FM) before and after water immersion were investigated, and all the results were statistically analyzed with ANOVA analysis. The results showed that DT and DS had comparable (ρ > 0.05) surface free energy which was lower than that of BT (ρ < 0.05). Compared with BT, with the same surface roughness (ρ > 0.05), less amount of S. mutans was accumulated on the surface of DT and DS (ρ < 0.05). In all DRCs, the DS had the best resistance to mucin adsorption (ρ < 0.05) due to its high hydrophobicity. Compared with BT, both DFMA based DRCs had advantages such as lower VS and SS (ρ < 0.05), lower WS and SL (ρ < 0.05), and better water resistance. The DS, which had antibacterial adhesion effect, mucin adsorption resistance, lowest VS and SL (ρ < 0.05), and the highest FS and FM no matter before or after water immersion (ρ < 0.05) was considered to have the best comprehensive properties in all DRCs.

Effect of Different Filler Contents and Printing Directions on the Mechanical Properties for Photopolymer Resins.

Photopolymer resins are widely used in the production of dental prostheses, but their mechanical properties require improvement. We evaluated the effects of different zirconia filler contents and printing directions on the mechanical properties of photopolymer resin. Three-dimensional (3D) printing was used to fabricate specimens using composite photopolymers with 0 (control), 3, 5, and 10 wt.% zirconia filler. Two printing directions for fabricating rectangular specimens (25 mm × 2 mm × 2 mm) and disk-shaped specimens (φ10 mm × 2 mm) were used, 0° and 90°. Three-point bending tests were performed to determine the flexural strengths and moduli of the specimens. The Vickers hardness test was performed to determine the hardness of the specimens. Tukey's multiple comparison tests were performed on the average values of the flexural strengths, elastic moduli, and Vickers hardness after one-way ANOVA (α = 0.05). The flexural strengths and elastic moduli at 0° from high to low were in the order of 0, 3, 10, and 5 wt.%, and those at 90° were in the order of 3, 0, 10, and 5 wt.% (p < 0.05). For 5 and 10 wt.%, no significant differences were observed in mechanical properties at 0° and 90° (p < 0.05). The Vickers hardness values at 0° and 90° from low to high were in the order of 0, 3, 5, and 10 wt.% (p < 0.05). Within the limits of this study, the optimal zirconia filler content in the photopolymer resin for 3D printing was 0 wt.% at 0° and 3 wt.% at 90°.

The antimicrobial, physical, and chemical properties of a riboflavin-loaded dental resin intended for antimicrobial photodynamic therapy.

BACKGROUND: Dental caries remain a significant global health challenge. Unfortunately, current dental materials lack sufficient antimicrobial power to address the pathogenic species involved in this disease. In this study the potential to load a dental resin blend (RB) with riboflavin (B2) for use in an antimicrobial photodynamic therapy (aPDT) approach was investigated. METHODS: B2 was added to our experimental RB (0.1 - 10 wt%). Upon investigating the degree of conversion and specimen integrity of the RB as a function of B2 concentration, it was determined that loading should be restricted to 0.1, 1.0, and 1.5 wt%. Subsequent investigation included water sorption (WS) and solubility (SL), as well as shear bond strength (SBS) and flexural strength (FS) of the specimens after 24 h and 28-day water storage. Lastly, the antimicrobial response of Streptococcus mutans (S. mutans) biofilm following 6 h growth and 60 s of blue LED light (1.3 J/cm2) in an aPDT-based approach was measured. RESULTS AND CONCLUSIONS: Adding up to 1.5 wt% B2 had minimal impact on the FS or SBS of the RB. However, aging for 28-days notably increased the FS by as much as 50% for the 1.5 wt% B2-loaded RB. In addition, adding 1.5 wt% B2 resulted in a significant reduction in WS/SL of the RB. Lastly, while adding B2 did not change the antimicrobial response, this was an initial study under these conditions and future investigation will seek to optimize light parameters to produce a more agonistic response. Overall, a riboflavin-loaded dental resin shows significant promise for utilization in restorative dentistry with aPDT.

Steam disinfection releases micro(nano)plastics from silicone-rubber baby teats as examined by optical photothermal infrared microspectroscopy.

Silicone-rubber baby teats used to bottle-feed infants are frequently disinfected by moist heating. However, infant exposure to small microplastics (<10 µm) potentially released from the heated teats by hydrothermal decomposition has not been studied, owing to the limitations of conventional spectroscopy in visualizing microplastic formation and in characterizing the particles at the submicrometre scale. Here both the surfaces of silicone teats subjected to steam disinfection and the wash waters of the steamed teats were analysed using optical-photothermal infrared microspectroscopy. This new technique revealed submicrometre-resolved steam etching on and chemical modification of the teat surface. Numerous flake- or oil-film-shaped micro(nano)plastics (MNPs) (in the size range of 0.6-332 µm) presented in the wash waters, including cyclic and branched polysiloxanes or polyimides, which were generated by the steam-induced degradation of the base polydimethylsiloxane elastomer and the polyamide resin additive. The results indicated that by the age of one year, a baby could ingest >0.66 million elastomer-derived micro-sized plastics (MPs) (roughly 81% in 1.5-10 µm). Global MP emission from teat disinfection may be as high as 5.2 × 1013 particles per year. Our findings highlight an entry route for surface-active silicone-rubber-derived MNPs into both the human body and the environment. The health and environmental risks of the particles are as yet unknown.

Wearable Pressure Sensors Based on MXene/Tissue Papers for Wireless Human Health Monitoring.

Though the widely available, low-cost, and disposable papers have been explored in flexible paper-based pressure sensors, it is still difficult for them to simultaneously achieve ultrahigh sensitivity, low limit and broad range of detection, and high-pressure resolution. Herein, we demonstrate a novel flexible paper-based pressure sensing platform that features the MXene-coated tissue paper (MTP) sandwiched between a polyimide encapsulation layer and a printing paper with interdigital electrodes. After replacing the polyimide with weighing paper in the MTP pressure sensor, the silver interdigital electrodes can be recycled through incineration. The resulting pressure sensor with polyimide or paper encapsulation exhibits a high sensitivity of 509.5 or 344.0 kPa-1, a low limit (∼1 Pa) and a broad range (100 kPa) of detection, and outstanding stability over 10 000 loading/unloading cycles. With ultrahigh sensitivity over a wide pressure range, the flexible pressure sensor can monitor various physiological signals and human movements. Configuring the pressure sensors into an array layout results in a smart artificial electronic skin to recognize the spatial pressure distribution. The flexible pressure sensor can also be integrated with signal processing and wireless communication modules on a face mask as a remote respiration monitoring system to wirelessly detect various respiration conditions and respiratory abnormalities for early self-identification of opioid overdose, pulmonary fibrosis, and other cardiopulmonary diseases.

Separation of 44Sc from 44Ti in the Context of A Generator System for Radiopharmaceutical Purposes with the Example of [44Sc]Sc-PSMA-617 and [44Sc]Sc-PSMA-I&T Synthesis.

Today, 44Sc is an attractive radionuclide for molecular imaging with PET. In this work, we evaluated a 44Ti/44Sc radionuclide generator based on TEVA resin as a source of 44Sc. The generator prototype (5 MBq) exhibits high 44Ti retention and stable yield of 44Sc (91 ± 6 %) in 1 mL of eluate (20 bed volumes, eluent-0.1 M oxalic acid/0.2 M HCl) during one year of monitoring (more than 120 elutions). The breakthrough of 44Ti did not exceed 1.5 × 10-5% (average value was 6.5 × 10-6%). Post-processing of the eluate for further use in radiopharmaceutical synthesis was proposed. The post-processing procedure using a combination of Presep® PolyChelate and TK221 resins made it possible to obtain 44Sc-radioconjugates with high labeling yield (≥95%) while using small precursor amounts (5 nmol). The proposed method takes no more than 15 min and provides ≥90% yield relative to the 44Sc activity eluted from the generator. The labeling efficiency was demonstrated on the example of [44Sc]Sc-PSMA-617 and [44Sc]Sc-PSMA-I&T synthesis. Some superiority of PSMA-I&T over PSMA-617 in terms of 44Sc labeling efficiency was demonstrated (likely due to presence of DOTAGA chelator in the precursor structure). It was also shown that microwave heating of the reaction mixture considerably shortened the reaction time and improved radiolabeling yield and reproducibility of [44Sc]Sc-PSMA-617 and [44Sc]Sc-PSMA-I&T synthesis.

Calcium hydroxyapatite nanoparticles as a reinforcement filler in dental resin nanocomposite.

The current study focuses on the fabrication of calcium hydroxyapatite (Ca10(PO4)6(OH)2) (HA) in a nanorange having whiskers- and cubic-shaped uniform particle morphology. The synthesized HA particles hold a promising feature as reinforcement fillers in dental acrylic resin composite. They increase the efficacy of reinforcement by length and aspect ratio, uniformity, and monodispersity. Therefore, the acrylic resin was reinforced with the as-synthesized monodispersed HA filler particles (0.2-1 Wt%). The presence of filler particles in the composite had a noticeable effect on the tribological and mechanical properties of the dental material. The morphological effect of HA particles on these properties was also investigated, revealing that cubic-shaped particles showed better results than whiskers. The as-fabricated composite (0.4 Wt%) of the cubic-shaped filler particles showed maximum hardness and improved antiwear/antifriction properties. Particle loading played its part in determining the optimum condition, whereas particle size also influenced the reinforcement efficiency. The current study revealed that particle morphology, particle size, uniformity, etc., of HA fillers, greatly influenced the tribological and mechanical properties of the acrylic resin-based nanocomposite. Improvement in the tribological properties of HA particle-reinforced acrylic resin composites (HA-acrylic resin) followed the trend as AR < CmC < WC < CC.

Rubber Seed Oil-Based UV-Curable Polyurethane Acrylate Resins for Digital Light Processing (DLP) 3D Printing.

Novel UV-curable polyurethane acrylate (PUA) resins were developed from rubber seed oil (RSO). Firstly, hydroxylated rubber seed oil (HRSO) was prepared via an alcoholysis reaction of RSO with glycerol, and then HRSO was reacted with isophorone diisocyanate (IPDI) and hydroxyethyl acrylate (HEA) to produce the RSO-based PUA (RSO-PUA) oligomer. FT-IR and 1H NMR spectra collectively revealed that the obtained RSO-PUA was successfully synthesized, and the calculated C=C functionality of oligomer was 2.27 per fatty acid. Subsequently, a series of UV-curable resins were prepared and their ultimate properties, as well as UV-curing kinetics, were investigated. Notably, the UV-cured materials with 40% trimethylolpropane triacrylate (TMPTA) displayed a tensile strength of 11.7 MPa, an adhesion of 2 grade, a pencil hardness of 3H, a flexibility of 2 mm, and a glass transition temperature up to 109.4 °C. Finally, the optimal resin was used for digital light processing (DLP) 3D printing. The critical exposure energy of RSO-PUA (15.20 mJ/cm2) was lower than a commercial resin. In general, this work offered a simple method to prepare woody plant oil-based high-performance PUA resins that could be applied in the 3D printing industry.

Perfluoro-tert-butanol for selective on-resin detritylation: a mild alternative to traditionally used methods.

Solid-phase synthesis of cyclic, branched or side-chain-modified peptides typically involves introduction of a residue carrying a temporary side-chain protecting group that undergoes selective on-resin removal. In particular, Nα-Fmoc-Nε-(4-methyltriphenylmethyl) (Mtt)-protected lysine and its shorter analogues are commercially available and extensively used in this context. Nevertheless, rapid reliable methods for on-resin removal of Mtt groups in the presence of tert-butyloxycarbonyl (Boc) groups are needed. Current commonly used conditions involve low concentrations (1-3%) of trifluoroacetic acid (TFA) in dichloromethane, albeit adjustment to each specific application is required to avoid premature removal of Boc groups or cleavage from the linker. Hence, a head-to-head comparison of several deprotection conditions was performed. The selected acids represent a wide range of acidity from TFA to trifluoroethanol. Also, on-resin removal of the N-(4-methoxytriphenylmethyl) (Mmt) and O-trityl groups (on serine) was investigated under similar conditions. The mildest conditions identified for Mtt deprotection involve successive treatments with 30% hexafluoroisopropanol (HFIP) or 30% perfluoro-tert-butanol [(CF3)3COH] in dichloromethane (3 × 5 or 3 × 15 min, respectively), while 30% HFIP, 30% (CF3)3COH, or 10% AcOH-20% trifluoroethanol (TFE) in CH2Cl2 (3 × 5 min) as well as 5% trichloroacetic acid in CH2Cl2 (3 × 2 min) enabled Mmt removal. Treatment with 1% TFA with/without 2% triisopropylsilane added (3 × 5 min), but also prolonged treatment with 30% (CF3)3COH (5 × 15 min), led to selective deprotection of an O-Trt group on a serine residue. In all cases, the sequences also contained N-Boc or O-tBu protecting groups, which were not affected by 30% HFIP or 30% (CF3)3COH even after a prolonged reaction time of 4 h. Finally, the optimized conditions involving HFIP or (CF3)3COH proved applicable also for selective deprotection of a longer resin-bound peptide [i.e., Ac-Gly-Leu-Leu-Lys(Mtt)-Arg(Pbf)-Ile-Lys(Boc)-Ser(tBu)-Leu-Leu-RAM-PS] as well as allowed for an almost complete deprotection of a Dab(Mtt) residue.