Recent Toolboxes for Chemoselective Dual Modifications of Proteins.

Site-selective chemical modifications of proteins have emerged as a potent technology in chemical biology, materials science, and medicine, facilitating precise manipulation of proteins with tailored functionalities for basic biology research and developing innovative therapeutics. Compared to traditional recombinant expression methods, one of the prominent advantages of chemical protein modification lies in its capacity to decorate proteins with a wide range of functional moieties, including non-genetically encoded ones, enabling the generation of novel protein conjugates with enhanced or previously unexplored properties. Among these, approaches for dual or multiple modifications of proteins are increasingly garnering attention, as it has been found that single modification of proteins is inadequate to meet current demands. Therefore, in light of the rapid developments in this field, this review provides a timely and comprehensive overview of the latest advancements in chemical and biological approaches for dual functionalization of proteins. It further discusses their advantages, limitations, and potential future directions in this relatively nascent area.

Internal Vanadium Doping and External Modification Design of P2-Type Layered Mn-Based Oxides as Competitive Cathodes toward Sodium-Ion Batteries.

P2-type layered manganese-based oxides have attracted considerable interest as economical, cathode materials with high energy density for sodium-ion batteries (SIBs). Despite their potential, these materials still face challenges related to sluggish kinetics and structural instability. In this study, a composite cathode material, Na0.67Ni0.23Mn0.67V0.1O2@Na3V2O2(PO4)2F was developed by surface-coating P2-type Na0.67Ni0.23Mn0.67V0.1O2 with a thin layer of Na3V2O2(PO4)2F to enhance both the electrochemical sodium storage and material air stability. The optimized Na0.67Ni0.23Mn0.67V0.1O2@5wt %Na3V2O2(PO4)2F exhibited a high discharge capacity of 176 mA h g-1 within the 1.5-4.1 V range at a low current density of 17 mA g-1. At an increased current density of 850 mA g-1 within the same voltage window, it still delivered a substantial initial discharge capacity of 112 mAh g-1. These findings validate the significant enhancement of ion diffusion capabilities and rate performance in the P2-type Na0.67Ni0.33Mn0.67O2 material conferred by the composite cathode.

Dual-modification strategy of Co(II) and g-C3N4 to CuS for efficient colorimetric determination of thioglycolic acid in daily cosmetics.

A conventional colorimetric method based on CuS-catalyzed H2O2 is improved by a dual-modification strategy and employed for thioglycolic acid (TGA) determination. The doping of Co(II) can enhance ion exchange efficiency. Meanwhile, the modification of g-C3N4 can increase specific surface area and decrease unspecific aggregation. The constructed g-C3N4/Co-CuS nanocomposite exhibited a favorable catalytic feature. A Michaelis constant (Km) value of 0.02 mM has been achieved, which is 1/160 of those of CuS and horseradish peroxidase (HRP). The g-C3N4/Co-CuS displays a rapid color response in 3 min and resulted in a stable measurable signal within 10 min. In the determination procedure, the sulfhydryl contained in TGA is capable of preventing TMB oxidation via competing the ·OH produced by catalysis and caused a color distinction that is related to the TGA amount. The distinctions of absorbance (λmax = 652 nm) of different concentrations of TGA are recorded. Linearity is obtained in the ranges of 2.5 - 20 µM and 20 - 160 µM, and the LOD is 0.14 µM. In the real sample assays of perm agent and Qianhu lake water, the recoveries were 96.70 - 106.84% and 100.21 - 101.90%, respectively. This demonstrates that the proposed dual-modification strategy for CuS contributes to highly efficient and convenient determination of TGA in daily cosmetics and water analysis.

Carioca bean starch upon synergic modification: characteristics and films properties.

BACKGROUND: The use of damaged beans for starch isolation comprises an end-use alternative for a product that is not accepted by the consumer. For that reason, isolation and modification of Carioca bean starch should be explored and evaluated as a suitable source for biodegradable material. The present study aimed to evaluate the synergism of physical and chemical modifications on Carioca bean starch with respect to improving the properties of biodegradable films. A heat-moisture treatment (HMT) followed by oxidation by sodium hypochlorite was performed and vice versa. RESULTS: Synergism was noted in the starch properties compared to the single modification. When the oxidation was applied first, a higher amylose and carbonyl content was noted. HMT, isolated and as a second modification, caused a more pronounced effect on viscosity profile than the oxidized starch, with an increase in paste temperature and a decrease in viscosity, breakdown and final viscosity. CONCLUSION: The results obtained in the present study reflect a decrease in water vapor permeability, although a higher tensile strength was noted when oxidation was applied, as a single and as a first modification. © 2020 Society of Chemical Industry.

Preparation and partial characterization of films made with dual-modified (acetylation and crosslinking) potato starch.

BACKGROUND: Starch is an alternative material for the production of biodegradable plastics; however, native starches have drawbacks due to their hydrophilic nature. Chemical modifications such as acetylation and crosslinking are used to broaden the potential end-uses of starch. Dual modification of starches increases their functionality compared to that of starches with similar single modifications. In this study, a dual-modified potato starch (acetylated and crosslinked) was used to produce films by casting. RESULTS: Changes in the arrangement of the amylopectin double helices of dual-modified starch were evident from X-ray diffraction patterns, pasting profiles and thermal properties. The degree of substitution for acetyl groups was low (0.058 ± 0.006) because crosslinking dominated acetylation. Modified starch film had higher elongation percentage (82.81%) than its native counterpart (57.4%), but lower tensile strength (3.51 MPa for native and 2.17 MPa for dual-modified) and lower crystallinity in fresh and stored films. The sorption isotherms indicated that the dual modification decreased the number of reactive sites for binding water, resulting in a reduction in the monolayer value and a decrease in the solubility and water vapor permeability. CONCLUSIONS: Dual modification of starch may be a feasible option for improving the properties of biodegradable starch films. © 2018 Society of Chemical Industry.

Development and characterization of biodegradable films from whey protein concentrate, psyllium husk and oxidized, crosslinked, dual-modified lotus rhizome starch composite.

BACKGROUND: The combined effect of variously chemically modified lotus rhizome starch, whey protein concentrate, psyllium husk and glycerol was evaluated on developed biodegradable films. RESULTS: Dual-modified lotus rhizome starch composite films presented minimum solubility and water vapor permeability and maximum tensile strength among native and modified starch composite films. Elongation at break of dual-modified starch composite films (FLCOS1 , FLCOS2 ) was found to be a maximum, whereas a decrease was observed for FLCOS3 . Oxidized lotus rhizome starch composite films were the most transparent among native and modified starch composite films, whereas crosslinked lotus rhizome starch composite films were the least transparent. Scanning electron microscopy indicated a homogeneous compact surface of oxidized starch composite films, whereas troughs were observed in crosslinked and dual-modified starch composite films. Using whey protein concentrate, psyllium husk and glycerol without any phase separation, smoother films and with compact microstructures were produced. Fourier transform infrared analysis revealed additional peaks for modified starch films, confirming greater interaction among starch and film-forming components, whereas amorphous structure was indicated from X-ray diffraction results of modified starch composite films. CONCLUSIONS: Owing to various properties of modified starches, these films find application in edible contact packages and can better be used for products where higher structural integrity and lower water vapor transmission are needed. © 2019 Society of Chemical Industry.

Optimization of carbamylation conditions and study on the effects on the product ions of carbamylation and dual modification of the peptide by Q-TOF MS.

Modified peptides fragmented by collision-induced dissociation can offer additional sequence information, which is beneficial for the de novo sequencing of peptides. Here, the model peptide VQGESNDLK was carbamylated. The optimal conditions were as follows: temperature of 90℃, pH of 7, and the time of 60 min. Then, we studied the b- and y-series ions of the native, carbamylated, and dual-modified peptides. The results were as follows. The short carbamylated peptides (≤10 amino acid residues) produced more b-series ions (including b1 ion). The long carbamylated peptides (>10 amino acid residues) produced additional b1 ion but fewer y-series ions (especially in the high-mass region). The short dual-modified peptides produced more b-series ions (including b1 ion) and more y-series ions, and their peptide sequence coverage was almost 100%. The long dual-modified peptides produce b1 ion and more y-series ions, and their peptide sequence coverage was nearly above 90%. Therefore, both carbamylation and the dual modification method could be used to identify the N-terminal amino acid, and the dual modification method was also excellent for the de novo sequencing of the tryptic peptides.

Enzymatically hydrolysed, acetylated and dually modified corn starch: physico-chemical, rheological and nutritional properties and effects on cake quality.

Corn starch was treated by enzymatic hydrolysis with Aspergillus oryzae S2 α-amylase, acetylation with vinyl acetate, and dual modification. The dual modified starch displayed a higher substitution degree than the acetylated starch and lower reducing sugar content than the hydrolysed starch. The results revealed that the cooling viscosity and amylose content of those products decrease (P < 0.05). An increase in moisture, water, and oil absorption capacity was observed for the acetylated starch and, which was less pronounced for the enzymatically hydrolysed starch but more pronounced for the enzymatically hydrolysed acetylated product. The latter product underwent an increase in resistant starch content, which is induced by a rise in hydrolysis time to attain about 67 % after 1 h of reaction. The modified starch samples were added to cake formulations at 5 and 10 % concentrations on a wheat flour basis and compared to native starch. The results revealed that when applied at 5 % concentrations, the modified starches reduced the hardness, cohesion, adhesion and chewiness of baked cakes and enhanced their elasticity, volume, height, crust color, and appearance as compared to native starch. These effects were more pronounced for the cake incorporating the dually modified starch.

Effects of enzyme hydrolysis-assisted fibrillation treatment on the solubility, emulsifying properties and antioxidant activity of rice protein.

This work aimed to explore the changes of rice protein (RP) in solubility, emulsifying properties, and antioxidant activity after the enzyme hydrolysis-assisted fibrillation dual modification. Results showed that enzyme hydrolysis by papain and fibrillation treatments significantly affected the secondary and tertiary structures of RP. The modified proteins, including RP hydrolysate (RPH), RP nanofibrils (RPN), and RPH nanofibrils (RPHN), demonstrated enhanced solubility and antioxidant activity compared to RP, with RPHN exhibiting the superior performance. The emulsifying capacity of RPH, RPN, and RPHN increased by 9.55 %, 22.86 %, and 26.57 %, respectively, compared to that of RP. Furthermore, RPHN displayed the highest emulsion stability index. Nanoemulsion stabilized by RPHN showed enhanced centrifugal, storage, and oxidative stabilities. Neither RPHN nor RPN exhibited cytotoxicity to human cell lines, and could provide nutrients for cells. Overall, the functional properties and antioxidant activity of RP were significantly improved by enzyme hydrolysis-assisted fibrillation dual modification. This study may provide reference for the development and utilization of nanofibrils from plant proteins.

Influence of dual succinylation and ultrasonication modification on the amino acid content, structural and functional properties of Chickpea (Cicer arietinum L.) protein concentrate.

Chickpea protein, a valuable plant-based source, offers versatile applications, yet the impact of modifications like succinylation and ultrasonication on its properties remains unclear. This study explored dual succinylation and ultrasonication modification to enhance its functionality and application. Modified chickpea protein with a degree of succinylation of 96.75 %, showed enhanced water holding capacity 39.83 %, oil holding capacity 54.02 %, solubility 7.20 %, and emulsifying capacity 23.17 %, compared to native protein. Despite reduced amino acid content (64.50 %), particularly lysine, succinylation increased sulfhydryl by 1.74 %, reducing hydrophobicity (Ho) by 41.87 % and causing structural changes. Ultrasonication further reduced particle size by 82.57 % and increased zeta potential and amino acid content (57.47 %). The dual-modified protein exhibited a non-significant increase in antimicrobial activity against Staphylococcus aureus (25.93 ± 1.36 mm) compared to the native protein (25.28 ± 1.05 mm). In conclusion, succinylation combined with ultrasonication offers a promising strategy to enhance chickpea protein's physicochemical properties for diverse applications.

Characteristics of rice starches modified by single and dual heat moisture and osmotic pressure treatments.

The effect of osmotic pressure treatment (OPT), heat moisture treatment (HMT), and their dual combination as HMT-OPT and OPT-HMT on functional and pasting properties, gel texture, crystallinity, thermal, morphological, and rheological properties, and in vitro digestibility of modified starches were investigated. HMT was done with 29 % moisture at 111 °C for 45 min while OPT was performed at 117 °C for 35 min with saturated sodium sulphate solution. All modifications increased amylose content, improved pasting stability, and reduced swelling power and solubility. Dual modifications caused higher morphological changes than single modified starches. HMT and OPT increased pasting temperature, setback and final viscosity while decreased peak viscosity and breakdown, whereas HMT-OPT and OPT-HMT reduced all pasting parameters except pasting temperature. 1047/1022 and 995/1022 ratios and relative crystallinity decreased. V-type polymorphs were formed, and gelatinization temperature range increased with lower gelatinization enthalpy. Starch gel elasticity, RS and SDS content were enhanced to a greater extent after HMT-OPT and OPT-HMT. HMT as a single and dual form with OPT showed prominent effect on pasting, thermal, crystalline, and rheological properties. Application of HMT, OPT and dual modified starches with improved functionalities may be targeted for suitable food applications such as noodles.

Enhanced barrier properties in sweet potato starch films via dual modification by octenyl succinylation and heat moisture treatment for use as plant-based sausage casings.

This study assesses the impact of dual modification [octenyl succinylation (OSA) and heat-moisture treatment (HMT)] of sweet potato starch (SPS) on the physicochemical, mechanical, and permeability properties of SPS film. The intrinsic limitations of starch films, such as sensitivity to high humidity, inferior mechanical properties, and weak barrier capabilities, have restricted their use in sausage casings. Nonetheless, the dual-modified SPS film (OSA@HMT-SPS film) demonstrated significantly reduced solubility (P < 0.05), moisture content, water vapor permeability (WVP), and O2 permeability compared to the SPS film. Furthermore, its flexibility and elasticity, indicated by its elongation at break, was notably superior. When used as sausage casings, the OSA@HMT-SPS film effectively mitigated lipid oxidation in sausages better than both the SPS film and commercial collagen casings, owing to its low O2 permeability. As a result, the OSA@HMT-SPS casing presents significant promise as a plant-based sausage casing alternative.

Caries-Prone Primary Teeth: A Hidden Reason and Prophylactic Treatment in the Viewpoint of Materials Science.

Dental caries, the most prevalent chronic disease across all age groups, has a high prevalence, particularly among children. However, there is no specific and effective treatment for the prevention of caries in primary teeth (Pr.T.), which stems from a lack of knowledge regarding the basic nature of the tooth surface. Herein, we observed that the adhesion energies of the caries-related bacteria Streptococcus mutans and Streptococcus sanguinis to Pr.T were approximately 10 and 5.5 times higher than those to permanent teeth (Pe.T). A lower degree of mineralization and more hydrophilic characteristics of the Pr.T enamel account for this discrepancy. Accordingly, we proposed that the on-target modification of both hydroxyapatite and organic components on Pr.T by dual modification would render a sufficient hydration layer. This resulted in an approximately 11-time decrease in bacterial adhesion energy after treatment. In contrast, a single hydroxyapatite modification on Pe.T and young permanent teeth (Y.Pe.T) was sufficient to achieve a similar effect. Theoretical simulation further verified the rationality of the approach. Our findings may help understand the reason for Pr.T being caries-prone and provide references for treatment using resin restorations. This strategy offers valuable insights into daily oral hygiene and dental prophylactic treatment in children.

Characterizations and film-forming properties of different fractionated high-amylose maize starches subjected to hydroxypropylation.

Dual-modifications of jet milling and hydroxypropylation were used to improve the functional properties of maize starch (HM, containing 67 % amylose). The fractions obtained in three sizes (HM-S, HM-M, HM-L) were further treated with 10 % and 30 % propylene oxide (PO10 and PO30). The infrared peak of starch at 2794 cm-1 indicated the successful introduction of hydroxypropyl groups. The molar degree of substitution (MS) increased with the degree of jet milling. The MS of HM-L-PO10 is 0.4, that of HM-M-PO10 is 0.7, and that of HM-S-PO10 is 0.9. The crystallinity of dual-modified HM increased, but the crystal type remained unchanged, still being B-type. Dual-modification significantly improved the performance of starch, and the higher the degree of modification, the better the optimization effect. The lowest enthalpy changes of gelatinization (ΔH = 3.49 J/g), the best freeze-thaw stability, the highest elongation at break (110.42 %) and transmittance (81.22 %) were shown in HM-S-PO30. The present study confirms that HM-S-PO30 films have the best physicochemical and mechanical properties, which provide new insights into optimizing starch-based packaging materials.

Exploring the effects of enzymatic and thermal treatments on banana starch characteristics.

Banana starch has a highly resistant starch (RS) and slow-digested starch (SDS) content, making it attractive as a functional ingredient. Unfortunately, banana starch requires modification processes due to the loss of RS and SDS during gelatinization because of its thermolabile characteristics. This study explores the effect of banana starch modification by enzymatic, heat moisture treatment (HMT) and dual modification (HMT+ enzymatic) on its nutritional (RS, SDS) and functional properties (hydration, structural, gelation, rheological). HMT and dual modifications decrease RS (from 44.62 g/100 g to 16.62 and 26.66 g/100 g, respectively) and increase SDS (from 21.72 g/100 g to 33.91 and 26.95 g/100 g, respectively) in raw starch but induce structural changes that enhance RS (from 3.10 g/100 g to 3.94 and 4.4 g/100 g, respectively) and SDS (from 2.58 g/100 g to 9.58 and 11.48 g/100 g) thermo-resistance in gelled starch. Also, changes in the functional properties of starches were evidenced, such as weaker gels (hardness < 41 g), lower water absorption (<12.35 g/g), high starch solubility (>1.77 g/100 g) and increased gelatinization temperature. Improved gelatinization temperature and RS thermostability resulted from modifications that could expand banana starch applications as a beverage and compote thickener agent.

Recent Advances in Polymers Bearing Activated Esters for the Synthesis of Glycopolymers by Postpolymerization Modification.

Glycopolymers are functional polymers with saccharide moieties on their side chains and are attractive candidates for biomaterials. Postpolymerization modification can be employed for the synthesis of glycopolymers. Activated esters are useful in various fields, including polymer chemistry and biochemistry, because of their high reactivity and ease of reaction. In particular, the formation of amide bonds caused by the reaction of activated esters with amino groups is of high synthetic chemical value owing to its high selectivity. It has been employed in the synthesis of various functional polymers, including glycopolymers. This paper reviews the recent advances in polymers bearing activated esters for the synthesis of glycopolymers by postpolymerization modification. The development of polymers bearing hydrophobic and hydrophilic activated esters is described. Although water-soluble activated esters are generally unstable and hydrolyzed in water, novel polymer backbones bearing water-soluble activated esters are stable and useful for postpolymerization modification for synthesizing glycopolymers in water. Dual postpolymerization modification can be employed to modify polymer side chains using two different molecules. Thiolactone and glycine propargyl esters on the polymer backbone are described as activated esters for dual postpolymerization modification.

Comprehensive review on single and dual modification of starch: Methods, properties and applications.

Starch is a natural, renewable, affordable, and easily available polymer used as gelling agents, thickeners, binders, and potential raw materials in various food products. Due to these techno-functional properties of starch, food and non-food industries are showing interest in developing starch-based food products such as films, hydrogels, starch nanoparticles, and many more. However, the application of native starch is limited due to its shortcomings. To overcome these problems, modification of starch is necessary. Various single and dual modification processes are used to improve techno-functional, morphological, and microstructural properties, film-forming capacity, and resistant starch. This review paper provides a comprehensive and critical understanding of physical, chemical, enzymatic, and dual modifications (combination of any two single modifications), the effects of parameters on modification, and their applications. The sequence of modification plays a key role in the dual modification process. All single modification methods modify the physicochemical properties, crystallinity, and emulsion properties, but some shortcomings such as lower thermal, acidic, and shear stability limit their application in industries. Dual modification has been introduced to overcome these limitations and maximize the effectiveness of single modification.

Effects of dual succinylation and ultrasonication modification on the structural and functional properties of ovalbumin.

In this study, the functional properties of ovalbumin (OVA) were improved through dual modification with succinylation (succinylation degrees of 32.1 % [S1], 74.2 % [S2], and 95.2 % [S3]) and ultrasonication (ultrasonication durations of 5 min [U1], 15 min [U2], and 25 min [U3]), and the changes in protein structures were explored. Results showed that as the succinylation degree was increased, the particle size and surface hydrophobicity of S-OVA decreased by the maximum values of 2.2 and 2.4 times, respectively, causing emulsibility and emulsifying stability to increase by 2.7 and 7.3 times, respectively. After ultrasonic treatment, the particle size of succinylated-ultrasonicated OVA (SU-OVA) had decreased by 3.0-5.1 times relative to that of S-OVA. Moreover, the net negative charge of S3U3-OVA had increased to the maximum value of - 35.6 mV. These changes contributed to the further enhancement in functional indicators. The unfolding of the protein structure and the conformational flexibility of SU-OVA were illustrated and compared with those of S-OVA via protein electrophoresis, circular dichroism spectroscopy, intrinsic fluorescence spectroscopy, and scanning electron microscopy. The dually modified OVA emulsion (S3U3-E) presented small droplets (243.33 nm), reduced viscosity, and weakened gelation behavior that were indicative of even distribution, which was visually proven by confocal laser scanning microscopy images. Furthermore, S3U3-E exhibited favorable stability, a particle size that was almost unchanged, and a low polydispersity index (<0.1) over 21 days of storage at 4 °C. The above results demonstrated that succinylation combined with ultrasonic treatment could be an effective dual modification method for enhancing the functional performance of OVA.

Spotlight on the Multiscale Structural and Physicochemical Properties of Red Adzuki Bean Starch through Partial Amylose Removal Combined with Hydrochloric Acid.

To explore the effect of amylose within starch granules on the efficiency of starch hydrolysis by acid, we chose the warm water extraction method to treat red adzuki bean starch to obtain different degrees of amylose removal granule models and to prepare samples in combination with acid hydrolysis. The amylose content was reduced after acid hydrolysis, reducing the peak viscosity (2599-1049 cP), while the solubility was significantly increased. In contrast, the short-chain content of the deamylose-acid hydrolysis samples was reduced considerably, exacerbating the trend towards reduced starch orderliness and increased solubility. This work reveals the granular structure of starch from the point of view of deamylose and contributes to a thorough understanding of the mechanisms of acid hydrolysis. It might add to knowledge in starch science research and industrial applications for the acid processing of starch-based foods, particularly with regard to the most important factors controlling the structure and function of starch.

Red rice starch modification - Combination of the non-thermal method with a pulsed electric field (PEF) and enzymatic method using α-amylase.

The objective of this study was to investigate the dual modification of red rice starch using pulsed electric field (PEF) and α-amylase, focusing on morpho-structural, thermal, and viscoamylographic properties. Native starch (Control) underwent various treatments: PEF at 30 kV cm-1 (PEF30), α-amylase at 9.0 U mg-1 (AA0), and a combination of both (PEF30 + α and α + PEF30). The PEF30 + α treatment exhibited the highest degree of digestion (10.66 %) and resulted in morphological changes in the starch granules, which became elongated and curved, with an increased average diameter of 50.49 µm compared to the control. The starch was classified as type A, with a maximum reduction in crystallinity of up to 21.17 % for PEF30. The deconvolution of FT-IR bands indicated an increase in the double helix degree (DDH) for PEF30 and AA0, while the degree of order (DO) was reduced for PEF30, AA0, and PEF30 + α. DSC analysis revealed significant modifications in gelatinization temperatures, particularly for PEF30, and these changes were supported by a reduction in gelatinization enthalpy (ΔH) of up to 28.05 % for AA0. These findings indicate that both individual and combined treatments promote a decrease in starch gelatinization and facilitate the process, requiring less energy. Differences were observed between the formulations subjected to single and alternating dual treatments, highlighting the influence of the order of PEF application on the structural characteristics of starch, especially when applied before the enzymatic treatment (PEF + α). Regarding the viscoamylographic parameters, it was observed that AA0 presented higher values than the control, indicating that α-amylase enhances the firmness of the paste. The double modification with PEF + α was more effective in reducing syneresis and starch retrogradation, leading to improvements in paste properties. This study provided significant insights into the modification of red rice starch using an efficient and environmentally friendly approach.