Search

In the growing field of personalized medicine, non-invasive wearable devices and sensors are valuable diagnostic tools for the real-time monitoring of physiological and biokinetic signals. Among all the possible multiple (bio)-entities, pH is important in defining health-related biological information, since its variations or alterations can be considered the cause or the effect of disease and disfunction within a biological system. In this work, an innovative (bio)-electrochemical flexible pH sensor was proposed by realizing three electrodes (working, reference, and counter) directly on a polyimide (Kapton) sheet through the implementation of CO2 laser writing, which locally converts the polymeric sheet into a laser-induced graphene material (LIG electrodes), preserving inherent mechanical flexibility of Kapton. A uniform distribution of nanostructured PEDOT:PSS was deposited via ultrasonic spray coating onto an LIG working electrode as the active material for pH sensing. With a pH-sensitive PEDOT coating, this flexible sensor showed good sensitivity defined through a linear Nernstian slope of (75.6 ± 9.1) mV/pH, across a pH range from 1 to 7. We demonstrated the capability to use this flexible pH sensor during dynamic experiments, and thus concluded that this device was suitable to guarantee an immediate response and good repeatability by measuring the same OCP values in correspondence with the same pH applied. [ABSTRACT FROM AUTHOR]

In this paper, poly (acrylamide-co-N-vinylcaprolactam) [poly(AM-co-NVCL)] hydrogels were modified by aqueous solution polymerization using sodium carboxymethyl cellulose (CMC-Na) and Laponite. Their properties were characterized by infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), rheological testing, and scanning electron microscopy (SEM). The swelling kinetics showed that the equilibrium swelling ratio of the xerogel was influenced by the monomer ratio, crosslinking agent, and modifier content. As the Laponite and CMC-Na content increased, the compressive strength of the composite hydrogel increased, while the elongation at break decreased. The modified composite hydrogel exhibited dual sensitivity to pH and temperature. DSC and rheological tests indicated that CMC-Na functioned as a physical crosslinking agent in the system, and with the increase in CMC-Na content, the crosslinking effect was enhanced. SEM demonstrated that the addition of Laponite and CMC-Na increased the number of pores in the hydrogel and decreased the pore size. [ABSTRACT FROM AUTHOR]

The anthocyanin extracts (AE) from different sources were commonly used in preparing an indicator film to reflect food freshness, as AE contained rich anthocyanins which acted as the pH-sensitive ingredient. Therefore, this study aimed to compare the impact of AE sources (including rosella extract (RE), Lycium ruthenicum Murray (LE), and mulberry extracts (ME)) on the film properties and pH-sensitivity of konjac glucomannan/zein (KZ) composite film. Results showed that the three AEs had significantly different anthocyanin species and total contents, contributing to their different color changes in response to the pH changes. Some film property changes were not affected by the different AE, but mostly, different film property changing extents were observed, such as thickness, color, mechanical properties, hydrophilicity, antioxidant property, and water vapor permeability. This indicated that the hydrophilic plasticizing and void-filling effects of the anthocyanin were impacted by the anthocyanin structure. On the other hand, the impact of AE sources on the pH sensitivity and volatile ammonia sensitivity of the films was significantly different, mainly relating to both anthocyanin contents and composition. Finally, the KZ film with LE addition of 10% was suggested to be applied in the intelligent food packaging, as the addition of anthocyanin was relatively low and the film had both good pH sensitivity and film properties. [ABSTRACT FROM AUTHOR]

Protein adsorption behavior was examined on poly(N-isopropylacrylamide-co-sodium methacrylate)-based hydrogels at different temperatures: 5, 20, and 37 °C, and pH: 4.5, 7, and 9.2. The hydrogels, whose covalent skeleton contains pendant anionic units due to the presence of the sodium methacrylate co-monomer, exhibited both thermo- and pH-sensitivity with different extents, which depended on the content of ionizable moieties and the cross-linker density. The hydrogel composition, temperature, and pH influenced the zeta potential of the hydrogels and their swelling properties. The proteins selected for the study, i.e., bovine serum albumin (BSA), ovalbumin (OVA), lysozyme (LYZ), and a monoclonal antibody (mAb2), differed in their aminoacidic composition and conformation, thus in isoelectric point, molecular weight, electrostatic charge, and hydrophobicity. Therefore, the response of their adsorption behavior to changes in the solution properties and the hydrogel composition was different. LYZ exhibited the strongest adsorption of all proteins with a maximum at pH 7 (189.5 m g   g g e l − 1 ); adsorption of BSA and OVA reached maximum at pH 4.5 (24.4 and 23.5 m g   g g e l − 1 ), whereas mAb2 was strongly adsorbed at 9.2 (21.7 m g   g g e l − 1 ). This indicated the possibility of using the hydrogels for pH-mediated separation of proteins differing in charge under mild conditions in a water-rich environment of both the liquid solution and the adsorbed phase. The adsorption affinity of all proteins increased with temperature, which was attributed to the synergistic effects of attractive electrostatic and hydrophobic interactions. That effect was particularly marked for mAb2, for which the temperature change from 5 to 37 °C caused a twentyfold increase in adsorption. In all cases, the proteins could be released from the hydrogel surface by a reduction in temperature, an increase in pH, or a combination of both. This allows for the elimination of the use of salt solution as a desorbing agent, whose presence renders the recycling of buffering solutions difficult. [ABSTRACT FROM AUTHOR]

Smart tags are used for monitoring the freshness of foods. However, they often lack significant color changes, and their accuracy needs to be improved. In this study, a poplar veneer with a natural pore structure was selected as a matrix to prepare a smart tag with high pH sensitivity for tracking the freshness of strawberries. The delignified veneer was modified using 2,3-epoxypropyltrimethylammonium chloride (EPTAC) to be given positive charges to adsorb bromothymol blue (BTB) through electrostatic interactions. The adsorption capacity of the veneer reached 7.0 mg/g at 50 °C for 4 h, and the veneer showed an obvious blue color. The smart tags exhibited distinct color changes at different pHs and showed quick color changes in response to acetic acid. As the freshness of strawberries decreased, the color of the smart tags changed from blue to yellow-green, which indicated that the accuracy was high. In this study, an effective method was fabricated to prepare a highly sensitive tag, promoting popular application to ensure food quality. [ABSTRACT FROM AUTHOR]

Chemical sensors are increasingly used in healthcare because of their small size, durability, low resistance, and quick reaction time. This research aims to develop a pH biosensor utilizing an ion-sensitive field-effect transistor (ISFET) simulated with Silvaco technology computer-aided design (TCAD) software. The pH range of operation for the ISFET is 2 to 12. Sensitivity was evaluated based on the critical pH value and threshold voltage (Vth) parameters across different gate channel lengths (250 nm, 200 nm, and 50 nm) and sensing membrane thicknesses (3 nm, 10 nm, and 20 nm). The sensitivity of different materials to pH levels was measured. Titanium dioxide (TiO2) had the highest sensitivity at 57.98 mV/pH, followed by hafnium (IV) oxide (HfO2) at 57.46 mV/pH, tantalum pentoxide (Ta2O5) at 57.36 mV/pH, aluminium oxide (Al2O3) at 55.05 mV/pH, and silicon nitride (Si3N4) at 54.75 mV/pH. Notably, TiO2 with a 200 nm gate channel length and a 3 nm sensing membrane thickness demonstrated the highest sensitivity. These findings highlight the potential of ISFETs, particularly those with TiO2 sensing membranes, as robust and precise pH monitoring platforms in the biomedical industry. [ABSTRACT FROM AUTHOR]

This review presents a comparative analysis of gelation properties in plant-based versus animal-based proteins, emphasizing key factors such as pH, ionic environment, temperature, and anti-nutritional factors. Gelation, a crucial process in food texture formation, is influenced by these factors in varying ways for plant and animal proteins. Animal proteins, like casein, whey, meat, and egg, generally show stable gelation properties, responding predictably to pH, temperature, and ionic changes. In contrast, plant proteins such as soy, pea, wheat, and oilseed show more variable gelation, often requiring specific conditions, like the presence of NaCl or optimal pH, to form effective gels. Animal proteins tend to gel more reliably, while plant proteins require precise environmental adjustments for similar results. Understanding these factors is crucial for selecting and processing proteins to achieve desired textures and functionalities in food products. This review highlights how changing these key factors can optimize gel properties in both plant- and animal-based proteins. [ABSTRACT FROM AUTHOR]

Rhodamine 6G (R6G) and 4-nitro-2,1,3-benzoxadiazole (NBD) linked through a spacer molecule spermidine (spd), R6G-spd-NBD, produces a fluorescent probe with pH-sensitive FRET (Förster (fluorescence) resonance energy transfer) effect that can be useful in a variety of diagnostic applications. Specifically, cancer cells can be spotted due to a local decrease in pH (Warburg effect). In this research, we applied this approach to intracellular infectious diseases—namely, leishmaniasis, brucellosis, and tuberculosis, difficult to treat because of their localization inside macrophages. R6G-spd-NBD offers an opportunity to detect such bacteria and potentially deliver therapeutic targets to treat them. The nanogel formulation of the R6G-spd-NBD probe (nanoparticles based on chitosan or heparin grafted with lipoic acid residues, Chit-LA and Hep-LA) was obtained to improve the pH sensitivity in the desired pH range (5.5–7.5), providing selective visualization and targeting of bacterial cells, thereby enhancing the capabilities of CLSM (confocal laser scanning microscopy) imaging. According to AFM (atomic force microscopy) data, nanogel particles containing R6G-spd-NBD of compact structure and spherical shape are formed, with a diameter of 70–100 nm. The nanogel formulation of the R6G-spd-NBD further improves absorption and penetration into bacteria, including those located inside macrophages. Due to the negative charge of the bacteria surface, the absorption of positively charged R6G-spd-NBD, and even more so in the chitosan derivatives' nanogel particles, is pronounced. Additionally, with a pH-sensitive R6G-spd-NBD fluorescent probe, the macrophages' lysosomes can be easily distinguished due to their acidic pH environment. CLSM was used to visualize samples of macrophage cells containing absorbed bacteria. The created nanoparticles showed a significant selectivity to model E. coli vs. Lactobacillus bacterial cells, and the R6G-spd-NBD agent, being a mild bactericide, cleared over 50% E.coli in conditions where Lactobacillus remained almost unaffected. Taken together, our data indicate that R6G-spd-NBD, as well as similar compounds, can have value not only for diagnostic, but also for theranostic applications. [ABSTRACT FROM AUTHOR]

Carbon nanoparticles (CNPs) emitting pH-dependent blue photoluminescence (PL) in aqueous solutions were solvothermally prepared and modified with a new fluorophore molecule, N-chlorobenzyl dithiomaleimide dimethyl diacetate (NCBDTM), with pH-dependent yellow-green PL in aqueous solutions and irreversible PL emission quenching in alkaline aqueous solutions at basic pHs. In the π-complex system formed by donor CNPs and acceptor NCBDTM molecules, energy transfer occurs by the FRET mechanism. Due to the implementation of the FRET mechanism, a significant Stokes shift of 170 nm is observed, making this and similar systems promising for the visualization of pH-dependent processes in the green-yellow visible light region. [ABSTRACT FROM AUTHOR]

In pursuit of improving dyeability and incorporating antimicrobial attributes into polyamide fabric, a series of mono-azo acid dyes (SN1–SN5) were synthesized. Sulfathiazole was employed as an intermediate in the synthesis process of the dyestuff. The resultant dyes were characterized by employing various analytical techniques. The antimicrobial efficiency of these colorant was established through testing against Aspergillus fumigatus, Staphylococcus aureus, and Escherichia coli, displaying a spectrum of mild to strong antibacterial activity. Dye SN5 exhibited the highest potency, showing growth inhibition of 90% and 95% against both bacterial strains, respectively. Since the acid dyes are the prime contenders for utilization in food, pharmaceuticals, and cosmetics, an assessment was conducted on BJ Human Fibroblast Cells to evaluate any plausible adverse impacts. The results revealed that all the dyes exhibited no cytotoxicity. The dyeing properties of these colorants, including color representation, build-up, exhaustion, and fixation, were thoroughly examined following their application on the fabrics. The fastness properties were found to be considerably good to excellent. The influence of acidic and alkaline conditions on the absorption maxima was also explored. The dye SN3 showed a substantial bathochromic shift with increase in the solution's acidity in comparison to other dyes. [ABSTRACT FROM AUTHOR]

The study proposed improving the arsenic encapsulation efficiency (EE) in liposomes and make it pH responsive. Liposomes were prepared using the ethanol injection method (EIM), thin film dispersion method (TFM), and CAGM with sodium arsenite (NaAsO2). The orthogonal experimental was used to optimize the preparation conditions of the CAGM. The arsenic-carrying liposomes were characterized by polydispersity index (PDI), transmission electron microscopy (TEM), in vitro release experiments, and inductively coupled plasma emission spectrum (ICP). The toxicity was investigated by rat glioma cells (C6) and human brain microvascular endothelial cells (HBMEC). The results indicated that the CAGM can effectively improve the EE of NaAsO2 and has a pH response compared with EIM and TFM. The size of nanoparticles prepared by CAGM was 118.8±56.67 nm, the arsenic EE was 54.3±9.82%, the drug loading rate was 7.13±0.72% (P<0.01), pH sensitivity was shown at pH 5.5. The optimal parameters of the CAGM were 3 mg NaAsO2, 5:1 egg phosphatidylcholine (EPC) to cholesterol (CHOL), and 240 mmol/L calcium acetate (CaAC2). The results showed that the CAGM has good biocompatibility and is one of the effective ways to improve the NaAsO2 encapsulation rate and pH response in liposome nanoparticles. [ABSTRACT FROM AUTHOR]

Intelligent single-layer packaging is widely used in food monitoring and storage. However, most single-layer intelligent packaging has poor mechanical strength and water barrier properties. In this study, a bilayer intelligent detector film based on polyvinyl alcohol-chitosan (PVA-CS)/nano-ZnO/sodium alginate (SA) combined with anthocyanin extract (cyanidin chloride) was prepared using a layer-by-layer solution casting assembly technique. The effects of different levels of anthocyanin extracts on the physical and functional properties of the films, including microstructure, mechanical property, barrier property, pH sensitivity, and antibacterial property, were investigated. The results show that the bilayers exhibit excellent physical properties, lower water vapor permeability, better light transmission and UV-blocking properties, a broader pH sensitivity (ΔE > 10), and good antibacterial activity. In short, the bilayer films studied are superior to the single-layer films in terms of their packaging potential for products with low moisture content, offering new directions for active intelligent packaging and biodegradable materials for the food industry. [ABSTRACT FROM AUTHOR]

The plant pigments called betalains are nutritionally safe polar compounds. They are subdivided into betaxanthins (having orange to yellow hues) and betacyanins (purple to red violet hues). Betacyanins change color with a change in pH, particularly in the range 6–8 and 9–11. Perishable foods like fish, chicken, beef, pork, and others tend to release total volatile base-nitrogen (TVB-N) during storage or deterioration, which leads to a change in the pH of pH-sensitive materials in the vicinity. pH-sensitive pigment-incorporated polymeric films with inherent active properties (or active/intelligent films) are increasingly being studied as an alternative to synthetic pH indicators to detect the accumulation of TVB-N by changing its color to indicate the stage of perishable food spoilage. There are many methods of developing such films under different conditions using different bio-based biodegradable polymer(s) and biocompatible plasticizer combinations. Among the reported methods, solution casting method has been the preferred one in most studies covered in this review. This method can be carried out under mild conditions. As such, betacyanins-incorporated polymeric films essentially require mild processing conditions because of their heat sensitivity, which will invariably affect the performance in food freshness monitoring. In this review, film fabrication parameters like temperature and duration of dissolution of polymers, plasticizer concentration, pH of the film-forming solution, film drying, and conditioning/aging, have been critically appraised based on the available literature. The lack of studies on the safety of active/intelligent films has been systematically highlighted in this review to focus future studies on this area. [ABSTRACT FROM AUTHOR]

The enzyme-based degradation of lignocellulose for bioenergy production is an eco-friendly and sustainable approach. This study aimed to elucidate the enzymatic characteristics of endoglucanase (EGL), β-glucosidase (BGL), and xylanase (XYN) from Trichoderma guizhouence NJAU4742, and to explore the potential mechanisms underlying their synergistic degradation of different natural substrates. The results demonstrated that the three enzymes possessed remarkable high-temperature catalytic activity, broad pH adaptability, and responsiveness to different metal ions. The functional group absorption peaks of different substrates were shifted and altered after the synergistic action, particularly for C=O and O-H. Simultaneously, the crystallinity index of wheat straw, soybean straw, rice straw, and corn straw decreased by 7.40%, 2.37%, 20.60%, and 7.67%, respectively, compared to CK (natural straw). Additionally, the dense structure of different substrates was destroyed, and the inner parenchyma began to be exposed after the synergistic action, as observed by SEM. These findings offer valuable theoretical guidance for the development of lignocellulase applications. [ABSTRACT FROM AUTHOR]

The water quality in headwater streams depends on the groundwater origin and its transport pathways before it eventually discharges as surface water. In this case study, we present the Ce anomaly of over 100 hemiboreal headwater streams in Sweden and discuss the potential of the Ce anomaly to define two stream end members as proxies for the stream origin. The data show a relation between topography and the Ce anomaly, with more negative values (−0.8 to −0.4) in hilly catchments with distinct slopes, defined as an oxidized groundwater end member. The second end member is dominated by groundwater discharge from reduced, organic-rich riparian and wetland soils (reduced groundwater) having small Ce anomalies (−0.3 to zero). Element concentrations show a wide range, depending on the end member of the stream. For example, redox elements (Fe, Mn, S and N) show concentrations up to five times in streams with small negative Ce anomalies (reduced groundwater) compared to the concentrations in streams with large negative Ce anomalies. While element concentrations (of the classic redox elements Fe, Mn, S, N) show seasonal variations due to a summer drought period and the resulting reduced conditions, the Ce anomaly is constant, offering an excellent indicator of the dominant groundwater flow paths regardless of seasonal variations.

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shenyang Pharmaceutical University is the property of Shenyang Pharmaceutical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fluorescent base analogues (FBAs) have become useful tools for applications in biophysical chemistry, chemical biology, live‐cell imaging, and RNA therapeutics. Herein, two synthetic routes towards a novel FBA of uracil named qU (quadracyclic uracil/uridine) are described. The qU nucleobase bears a tetracyclic fused ring system and is designed to allow for specific Watson‐Crick base pairing with adenine. We find that qU absorbs light in the visible region of the spectrum and emits brightly with a quantum yield of 27 % and a dual‐band character in a wide pH range. With evidence, among other things, from fluorescence lifetime measurements we suggest that this dual emission feature results from an excited‐state proton transfer (ESPT) process. Furthermore, we find that both absorption and emission of qU are highly sensitive to pH. The high brightness in combination with excitation in the visible and pH responsiveness makes qU an interesting native‐like nucleic acid label in spectroscopy and microscopy applications in, for example, the field of mRNA and antisense oligonucleotide (ASO) therapeutics. [ABSTRACT FROM AUTHOR]

Dental caries is caused by acids from biofilms. pH-sensitive nanoparticle carriers could achieve improved targeted effectiveness. The objectives of this study were to develop novel mesoporous silica nanoparticles carrying nanosilver and chlorhexidine (nMS-nAg-Chx), and investigate the inhibition of biofilms as well as the modulation of biofilm to suppress acidogenic and promote benign species for the first time. nMS-nAg was synthesized via a modified sol-gel method. Carboxylate group functionalized nMS-nAg (COOH-nMS-nAg) was prepared and Chx was added via electrostatic interaction. Minimal inhibitory concentration (MIC), inhibition zone, and growth curves were evaluated. Streptococcus mutans (S. mutans), Streptococcus gordonii (S. gordonii), and Streptococcus sanguinis (S. sanguinis) formed multispecies biofilms. Metabolic activity, biofilm lactic acid, exopolysaccharides (EPS), and TaqMan real-time polymerase chain reaction (RT-PCR) were tested. Biofilm structures and biomass were observed by scanning electron microscopy (SEM) and live/dead bacteria staining. nMS-nAg-Chx possessed pH-responsive properties, where Chx release increased at lower pH. nMS-nAg-Chx showed good biocompatibility. nMS-nAg-Chx exhibited a strong antibacterial function, reducing biofilm metabolic activity and lactic acid as compared to control (p < 0.05, n = 6). Moreso, biofilm biomass was dramatically suppressed in nMS-nAg-Chx groups. In control group, there was an increasing trend of S. mutans proportion in the multispecies biofilm, with S. mutans reaching 89.1% at 72 h. In sharp contrast, in nMS-nAg-Chx group of 25 μg/mL, the ratio of S. mutans dropped to 43.7% and the proportion of S. gordonii and S. sanguinis increased from 19.8% and 10.9 to 69.8% and 56.3%, correspondingly. pH-sensitive nMS-nAg-Chx had potent antibacterial effects and modulated biofilm toward a non-cariogenic tendency, decreasing the cariogenic species nearly halved and increasing the benign species approximately twofold. nMS-nAg-Chx is promising for applications in mouth rinse and endodontic irrigants, and as fillers in resins to prevent caries. [Display omitted] [ABSTRACT FROM AUTHOR]

Environment-responsive hydrogels are environmentally friendly polymeric materials that rapidly respond to their environment by changing their volume or strength when the external environment, such as temperature, pH, light, and magnetism, changes. As environment-responsive hydrogels, they are uniquely flexible and sensitive, enabling them to be used in various applications, and are now at the forefront of polymer science research. Scholars have reviewed more environmentresponsive hydrogels in biomedicine, detection sensors, and drug release. We present a detailed description of the reaction mechanism and preparation process of environment-responsive hydrogels, taking temperature-responsive, pH-responsive, and light-responsive hydrogels as examples. Finally, a summary is given at the end: 1) the application of environmentally responsive hydrogels in agriculture, and 2) the problems and future trends of their application in agriculture. [ABSTRACT FROM AUTHOR]

This review presents a comparative analysis of gelation properties in plant-based versus animal-based proteins, emphasizing key factors such as pH, ionic environment, temperature, and anti-nutritional factors. Gelation, a crucial process in food texture formation, is influenced by these factors in varying ways for plant and animal proteins. Animal proteins, like casein, whey, meat, and egg, generally show stable gelation properties, responding predictably to pH, temperature, and ionic changes. In contrast, plant proteins such as soy, pea, wheat, and oilseed show more variable gelation, often requiring specific conditions, like the presence of NaCl or optimal pH, to form effective gels. Animal proteins tend to gel more reliably, while plant proteins require precise environmental adjustments for similar results. Understanding these factors is crucial for selecting and processing proteins to achieve desired textures and functionalities in food products. This review highlights how changing these key factors can optimize gel properties in both plant- and animal-based proteins.

Rhodamine 6G (R6G) and 4-nitro-2,1,3-benzoxadiazole (NBD) linked through a spacer molecule spermidine (spd), R6G-spd-NBD, produces a fluorescent probe with pH-sensitive FRET (Förster (fluorescence) resonance energy transfer) effect that can be useful in a variety of diagnostic applications. Specifically, cancer cells can be spotted due to a local decrease in pH (Warburg effect). In this research, we applied this approach to intracellular infectious diseases—namely, leishmaniasis, brucellosis, and tuberculosis, difficult to treat because of their localization inside macrophages. R6G-spd-NBD offers an opportunity to detect such bacteria and potentially deliver therapeutic targets to treat them. The nanogel formulation of the R6G-spd-NBD probe (nanoparticles based on chitosan or heparin grafted with lipoic acid residues, Chit-LA and Hep-LA) was obtained to improve the pH sensitivity in the desired pH range (5.5–7.5), providing selective visualization and targeting of bacterial cells, thereby enhancing the capabilities of CLSM (confocal laser scanning microscopy) imaging. According to AFM (atomic force microscopy) data, nanogel particles containing R6G-spd-NBD of compact structure and spherical shape are formed, with a diameter of 70–100 nm. The nanogel formulation of the R6G-spd-NBD further improves absorption and penetration into bacteria, including those located inside macrophages. Due to the negative charge of the bacteria surface, the absorption of positively charged R6G-spd-NBD, and even more so in the chitosan derivatives’ nanogel particles, is pronounced. Additionally, with a pH-sensitive R6G-spd-NBD fluorescent probe, the macrophages’ lysosomes can be easily distinguished due to their acidic pH environment. CLSM was used to visualize samples of macrophage cells containing absorbed bacteria. The created nanoparticles showed a significant selectivity to model E. coli vs. Lactobacillus bacterial cells, and the R6G-spd-NBD agent, being a mild bactericide, cleared over 50% E.coli in conditions where Lactobacillus remained almost unaffected. Taken together, our data indicate that R6G-spd-NBD, as well as similar compounds, can have value not only for diagnostic, but also for theranostic applications.

The hydrogels prepared using natural sources are of great importance in various applications due to their biodegradable and biocompatible features. In this work, a novel nanocomposite hydrogel based on the Gum extracted from Elaeagnus angustifolia was prepared and characterized. Graft copolymerization of Acrylic acid (AA) and Acrylamide (AAm) monomers was done on the polysaccharide chains of E. angustifolia Gum (EAG). To improve the physical and mechanical properties of the synthesized hydrogel, Cloisite 15A was used in different amounts as additive and physical cross-linking agent. The prepared hydrogels based on EAG polysaccharides were chemically and structurally characterized by FTIR spectroscopy, XRD analysis and SEM images. Incorporation of Cloisite 15A altered the porosity and network structure of the hydrogels-based EAG by acting as a physical cross-linker. So, the hydrogel containing Cloisite 15A showed improved water absorption and mechanical properties. Also, it was observed that the nanocomposite hydrogels have better performance in solutions with various pH values and saline solutions. The rheological studies showed that by the application of 3% wt of Cloisite 15A, the gel characteristics of the nanocomposite hydrogel are enhanced due to the optimum density of physical cross-linking in hydrogel structure. Accordingly, due to the natural source and proper physicochemical properties, the prepared hydrogel can be potentially used as water reservoir system in various agricultural and hygienic applications. [ABSTRACT FROM AUTHOR]

A set of experiments were conducted to screen the most thermo‐resistant microorganism and spoilage enzyme in sweet lime juice. Furthermore, the impact of matrix pH on the batch thermal treatment (75–95°C/0–10 min) intensities on Saccharomyces cerevisiae survival, PPO inactivation, and vitamin C retention in the sweet lime juice was evaluated. The influence of cumulative come‐up time (tCUT) and cooling time (tCOOL) was separated from the isothermal holding period (tHOLD). All three responses fitted best to the first‐order kinetics. The rate constants (k) ranged between 0.0053 and 0.471 s−1 (for S. cerevisiae), 0.00114 and 0.00731 s−1 (for PPO), and 0.000017 and 0.000142 s−1 (for vitamin C). The microbial and enzyme inactivation rate increased at a low pH level for a certain temperature, whereas, for vitamin C, an opposite trend was prominent through marginal. A new global kinetic model for k as a function of matrix pH and the temperature was developed in which the sensitivity of k to pH change was introduced as SpH. The optimized thermally pasteurized juice (95°C/298 s of holding time) at pH 3.5 showed >5 log cycle reduction in S. cerevisiae count (t5D, s) and 99% inactivation in PPO activity (t99, s) while retaining 57% vitamin C and 39% loss in total phenolics. The optimally treated pasteurized sample at pH 3.5 was examined for phenolic profiling, microbial cell morphology, and enzyme conformational change. The thermally pasteurized sample had a sensory acceptance of 6.9 out of 9 scales. Practical applications: The present study developed a systematic study for designing a thermal pasteurization condition for sweet lime juice. First, the most thermo‐resistant microorganism and spoilage enzymes in sweet lime juice were screened out based on the sensitivity index. Further, a global kinetic model was developed for the most resistant microorganisms, resistant enzymes, and vitamin C. This model can describe the impact of matrix pH and temperature on the treatment time to achieve microbial safety and enzymatic stability. Pasteurization time was estimated for each combination of pH and temperature. Assessing the impact of pH levels in the matrix on the effectiveness of thermal pasteurization would assist the industry in determining optimal harvesting conditions for fruit with the desired pH. [ABSTRACT FROM AUTHOR]

The genetic causes of global developmental delay (GDD) and intellectual disability (ID) are diverse and include variants in numerous ion channels and transporters. Loss-of-function variants in all five endosomal/lysosomal members of the CLC family of Cl- channels and Cl-/H+ exchangers lead to pathology in mice, humans, or both. We have identified nine variants in CLCN3, the gene encoding CIC-3, in 11 individuals with GDD/ID and neurodevelopmental disorders of varying severity. In addition to a homozygous frameshift variant in two siblings, we identified eight different heterozygous de novo missense variants. All have GDD/ID, mood or behavioral disorders, and dysmorphic features; 9/11 have structural brain abnormalities; and 6/11 have seizures. The homozygous variants are predicted to cause loss of ClC-3 function, resulting in severe neurological disease similar to the phenotype observed in Clcn3-/- mice. Their MRIs show possible neurodegeneration with thin corpora callosa and decreased white matter volumes. Individuals with heterozygous variants had a range of neurodevelopmental anomalies including agenesis of the corpus callosum, pons hypoplasia, and increased gyral folding. To characterize the altered function of the exchanger, electrophysiological analyses were performed in Xenopus oocytes and mammalian cells. Two variants, p.Ile607Thr and p.Thr570Ile, had increased currents at negative cytoplasmic voltages and loss of inhibition by luminal acidic pH. In contrast, two other variants showed no significant difference in the current properties. Overall, our work establishes a role for CLCN3 in human neurodevelopment and shows that both homozygous loss of ClC-3 and heterozygous variants can lead to GDD/ID and neuroanatomical abnormalities.

C-reactive protein (CRP) is an inflammation biomarker that requires simple and real-time monitoring for accurate diagnosis. Conventional CRP tests are complicated, expensive, and time-consuming. Field-effect transistor (FET)-based affinity sensors are seen as the ideal solution but it is difficult to obtain FET with sensitive gate structures. In this work, we propose a simple method of chemically modifying the gate surface of a commercial ion-sensitive FET (ISFET) with (3-glycidyloxypropyl)trimethoxysilane (GPTMS) to lower the background noise signal and then immobilize aptamers that provide significant surface potential change when they bind to CRP. The FET aptasensor was able to measure 0.002–20 μg/mL CRP in 1 × phosphatebuffered saline (PBS) with a higher sensitivity than the nonmodified ISFET sensors with their original pH sensitivity and was on par with other FET sensors without needing expensive nanomaterial or complicated nanofabrication. [ABSTRACT FROM AUTHOR]

The objective of this study is to harness the potential of biomineralization for the controlled fabrication of tetrahedral DNA (TDN)-mediated calcium carbonate (CaCO3) nanoparticles with applications in cancer therapy. While TDN has emerged as an efficient anti-cancer drug carrier, its inherent instability under physiological conditions poses challenges for sustained drug release. Biomineralization, known for its ability to maintain carrier morphology and stability in physiological environments, is leveraged in this research to enhance TDN's drug delivery capabilities. In this study, we successfully synthesized TDN-mediated CaCO3 nanoparticles through a biomineralization process, with comprehensive characterization utilizing TEM, SEM, AFM, and DLS techniques. The morphology and crystal phase of the resulting CaCO3 nanoparticles, ranging from 10 to 100 nm, are precisely controlled by the presence of TDN. Remarkably, the engineered nanoparticles demonstrated efficient loading and controlled delivery of the anti-cancer drug doxorubicin (Dox), suggesting their potential for cancer therapy. The TDN-CaCO3 nanoparticles exhibited notable attributes including high drug loading efficiency (42.2%), favorable biocompatibility, pH responsiveness, and minimal cytotoxicity. The findings of this study underscore the potential of TDN-CaCO3 nanoparticles as a promising therapeutic agent for safe and effective cancer treatment, offering new avenues for innovative and efficient drug delivery strategies in the future. [ABSTRACT FROM AUTHOR]

Immune checkpoint blockade (ICB) antibody such as anti-PD-L1 (aPD-L1) activates cytotoxic T cells (CTLs) to combat cancer, but they showed poor efficacy in prostate cancer (PCa). Lysosome-dependent autophagy is utilized by cancer cells to degrade their MHC-I and to lower their vulnerability to TNF- α and CTLs. Lysosomal pH-sensitive polymeric nanoparticle as a drug delivery carrier may also be a novel autophagy inhibitor to boost immunotherapy, but such an important effect has not been investigated. Herein, we developed a unique tumor acidity-activatable macromolecular nanodrug (called P-PDL1-CP) with the poly(2-diisopropylaminoethyl methacrylate) (PDPA) core and the conjugations of both aPD-L1 and long-chain polyethylene glycol (PEG) coating. The PDPA core was demonstrated to disturb lysosome to block the autophagic flux, thus elevating the cancer cell's MHC-I expression and vulnerability to the TNF- α and CTLs. Long-chain PEG facilitated a good tumor accumulation of P-PDL1-CP nanodrug. Furthermore, P-PDL1-CP nanodrug inhibited tumor autophagy, which synergized with aPD-L1 to promote the tumor-infiltrating CTLs and DCs maturation, to elevate intratumoral TNF- α and IFN- γ levels, and to elicit an anti-tumor immune memory effect in mice for PCa growth inhibition with low side effects. This study verified the synergistic anti-PCa treatment between autophagy inhibition and PD-L1 blockade and meantime broadened the application of pH-sensitive macromolecular nanodrug. A macromolecular nanodrug, comprising the PDPA core and the surface conjugation of both aPD-L1 antibodies and long-chain PEG coating via a tumor acidity-labile α -carboxy-dimethylmaleic anhydride amine bond, was developed. Tumoral acidity triggered the release of aPD-L1 for immunotherapy. Meantime, the charge switch of the remanent nanodrug enhanced the cancer cell uptake of PDPA, which disturbed the lysosomes to inhibit autophagy. This advanced nanodrug promoted the tumor-infiltrating CTLs and DCs maturation, elevated the intratumoral TNF- α and IFN- γ levels, and elicited the robust anti-tumor immune memory effect. This study demonstrated that the pH-sensitive PDPA macromolecule could serve as a carrier for the aPD-L1 delivery and as an efficient autophagy inhibitor to boost the immunotherapy of prostate cancer. [Display omitted] [ABSTRACT FROM AUTHOR]

We report the rheological behavior of aqueous solutions of a graft copolymer polyampholyte, constituted of polyacrylic acid (PAA) backbone grafted by Poly(L-lysine) (PAA-b-PLL). The graft copolymer self-assembles in aqueous media, forming a three-dimensional (3D) network through polyelectrolyte complexation of the oppositely charged PAA and PLL segments. Rheological investigations showed that the hydrogel exhibits interesting properties, namely, relatively low critical gel concentration, elastic response with slow dynamics, remarkable extended critical strain to flow, shear responsiveness, injectability, 3D printability and self-healing. Due to the weak nature of the involved polyelectrolyte segments, the hydrogel properties display pH-dependency, and they are affected by the presence of salt. Especially upon varying pH, the PLL secondary structure changes from random coil to α-helix, affecting the crosslinking structural mode and, in turn, the overall network structure as reflected in the rheological properties. Thanks to the biocompatibility of the copolymer constituents and the biodegradability of PLL, the designed gelator seems to exhibit potential for bioapplications. [ABSTRACT FROM AUTHOR]

The toxic effects of chemotherapy drugs on normal tissues are still a major limiting factor in cancer treatment. In this paper, we report a metal-organic framework (Zn-Co ZIF) with chitosan-coated outer layer as a carrier for the drug adriamycin hydrochloride (DOX), a treatment for liver cancer, as a novel anticancer nanodrug-enhanced carrier. Gold nanoparticles, a good photothermal conversion agent, were combined with the target SH-RGD during surface functionalisation to prepare Zn-Co ZIF@DOX-CS-Au-RGD (ZD-CAR), a nanoplatform with good photothermal conversion properties and targeting for combined liver cancer therapy. ZD-CAR was developed after RGD accurately targeted the tumour and entered the tumour microenvironment (TME), it cleaves and releases the liver cancer therapeutic agent (DOX) in a weak acidic environment to effectively kill tumour cells. The metal skeleton cleavage releases Co2+, which catalyzes the production of oxygen from H2O2 to alleviate the tumour hypoxic environment. The dissolved oxygen could reach 14 mg/L after adding 80 mg/mL of ZD-CAR. Meanwhile, gold nanoparticles could convert light energy into heat energy under 808 NIR irradiation to induce local superheating and kill tumour cells. In summary, this study developed a nanoplatform that combines chemo-photothermal-targeted therapy. It has shown good therapeutic effeciency in cellular experiments and performance tests and has promising applications in anti-cancer therapy. [ABSTRACT FROM AUTHOR]

In the treatment of solid tumors, the complex barriers composed of cancer‐associated fibroblasts (CAFs) prevent drug delivery and T cells infiltration into tumor tissues. Although nanocarriers hold great prospects in drug delivery, fibrosis causes the biological barrier and immunosuppressive tumor microenvironment (ITM) that impairs the anti‐tumor efficacy of nanocarriers. Here, a small dendritic macromolecule loaded with doxorubicin (PAMAM‐ss‐DOX) (DP) is synthesized and encapsulated into pH‐responsive nanoliposome, together with adjuvant toll‐like receptor 7/8 (TLR7/8) agonist resiquimod (R848) and losartan (LOS). The pH‐responsive liposome facilitates the simultaneous and effective delivery of DP, R848, and LOS, which can decompose and release these drugs under the acidic tumor microenvironment. The small sized DP (≈25 nm) with the ability to penetrate into tumor tissue and immunogenic cell death (ICD) can reverse the ITM and elicit immune response, which is equivalent to the effect of an in situ vaccine. Moreover, LOS reduces the activity of CAFs effectively, which can contribute to the infiltration of T cells. Therefore, this nano‐platform provides a new therapeutic strategy for enhanced chemo‐immunotherapy. [ABSTRACT FROM AUTHOR]

A cellulose-based matrix for monitoring milk freshness (MF) was produced from rice straw particles (RSPs) in a 0.125–0.150 mm that was bis-quaternized to attach bromocresol purple (BP) as a sensor. Under alkali conditions, the obstinate structure of the rice straw had opened, thereby improving the accessibility of the cellulose. Bis-quaternization created more adsorption sites for BP. The maximum adsorption capacity was 97.68 mg/g. The sensors were interwoven with cellulosic fibers to form the cellulose-based label with a relatively loose three-dimensional structure via hydrogen bonds. As the proportion of BP-BCRPs was increased from 10% to 40%, the air permeability of the label increased from 3.76 to 15.01 mm/s, which increased the response to the tested gases (10.12 s for 1 mL of acetic acid). The intelligent label exhibited excellent sensitivity at pH values of 3–9 with highly saturated color changes. During the storage period, the label color shifted from blue-purple to yellow as acidity was increased from 17.24 to 19.8 °T due to capillarity action, providing a timely warning to consumers. The prepared colorimetric porous intelligent cellulose-based label is suitable for monitoring of MF. [ABSTRACT FROM AUTHOR]

The enzyme-based degradation of lignocellulose for bioenergy production is an eco-friendly and sustainable approach. This study aimed to elucidate the enzymatic characteristics of endoglucanase (EGL), β-glucosidase (BGL), and xylanase (XYN) from Trichoderma guizhouence NJAU4742, and to explore the potential mechanisms underlying their synergistic degradation of different natural substrates. The results demonstrated that the three enzymes possessed remarkable high-temperature catalytic activity, broad pH adaptability, and responsiveness to different metal ions. The functional group absorption peaks of different substrates were shifted and altered after the synergistic action, particularly for C=O and O-H. Simultaneously, the crystallinity index of wheat straw, soybean straw, rice straw, and corn straw decreased by 7.40%, 2.37%, 20.60%, and 7.67%, respectively, compared to CK (natural straw). Additionally, the dense structure of different substrates was destroyed, and the inner parenchyma began to be exposed after the synergistic action, as observed by SEM. These findings offer valuable theoretical guidance for the development of lignocellulase applications.

Head and neck squamous cell carcinoma (HNSCC) is a common tumor type. At present, surgical treatment, radiotherapy and chemotherapy are the main treatments for HNSCC, but these treatments have not achieved satisfactory results. The pH-sensitive drug delivery system is an environmental stimuli-responsive drug delivery system that utilizes the stimulation of environmental pH to produce corresponding changes in physical structure or chemical properties, thereby regulating drug release. This delivery system is the focus of the research field of drug delivery systems. At present, the drugs used in the pH-sensitive drug delivery system in the treatment of HNSCC include adriamycin, taxanes, 5-fluorouracil, and cisplatin, and have shown good stability, tumor targeting, and drug release controllability in preclinical studies. This demonstrates great value in clinical transformation. At present, the pH-sensitive drug delivery system faces issues such as difficulty in particle size control, low drug loading, and possible immune response reactivity. Therefore, the pH-sensitive drug delivery system is still being improved. This article reviews the theoretical basis and research progress of the pH-sensitive drug delivery system in the treatment of HNSCC.

Currently, the dynamic erosive small molecule nano-prodrug is of great demand for oral chemotherapy, owing to its precise structure, high drug loading and improved oral bioavailability via overcoming various physiologic barriers in gastrointestinal tract, blood circulation and tumor tissues compared to other oral nanomedicines. Herein, this work highlights the successful development of pH-triggered dynamic erosive small molecule nano-prodrugs based on in vivo significant pH changes, which are synthesized via amide reaction between chlorambucil and star-shaped ortho esters. The precise nano-prodrugs exhibit extraordinarily high drug loading (68.16%), electric neutrality, strong hydrophobicity, and dynamic large-to-small size transition from gastrointestinal pH to tumoral pH. These favorable physicochemical properties can effectively facilitate gastrointestinal absorption, blood circulation stability, tumor accumulation, cellular uptake, and cytotoxicity, therefore achieving high oral relative bioavailability (358.72%) and significant tumor growth inhibition while decreasing side effects. Thus, this work may open a new avenue for robust oral chemotherapy attractive for clinical translation.

The interest in pH-sensitive textile sensors is growing in the global market. Due to their low-cost production, mechanical stability, flexibility, air-permeability, washability, and reusability, they are more suitable than electronic sensor systems. The research tailored the pH-sensitive textile by applying the pH indicator methyl orange to the cotton fabric during conventional dyeing. Adsorption of methyl orange dye to cotton fabric is hindered due to electrostatic repulsive forces between dye anions and negatively charged cotton fibre. To overcome this problem, chemical modification of cotton fabric using a commercial product was performed. The pH sensitivity of the dyed fabric was spectrophotometrically evaluated. In addition, the colour fastness of dyed cotton fabric to washing, light, hot pressing and rubbing was investigated according to valid SIST EN ISO standards. The research results show that the pH-responsive cotton fabric was successfully developed. The chemical modification of cotton fabric is crucial for the increased adsorption of methyl orange dye. The halochromic effect was not only perceived spectrophotometrically but also with the naked eye. The developed halochromic cotton fabric showed poor colour fastness to light and good colour fastness to hot pressing and rubbing, while no significant improvement in colour fastness to washing was observed, even though the fabric was after-treated with a cationic fixing agent. Higher adsorption of the methyl orange dye to the cotton fabric during the dyeing process leads to less wastewater pollution after dyeing with unfixed dye and, thus, a reduction in wastewater treatment costs. [ABSTRACT FROM AUTHOR]

Dual antimicrobial materials that have a combination of antimicrobial and antifouling properties were developed. They were developed through modification using gamma radiation of poly (vinyl chloride) (PVC) catheters with 4-vinyl pyridine (4VP) and subsequent functionalization with 1,3-propane sultone (PS). These materials were characterized by infrared spectroscopy, thermogravimetric analysis, swelling tests, and contact angle to determine their surface characteristics. In addition, the capacity of the materials to deliver ciprofloxacin, inhibit bacterial growth, decrease bacterial and protein adhesion, and stimulate cell growth were evaluated. These materials have potential applications in the manufacturing of medical devices with antimicrobial properties, which can reinforce prophylactic potential or even help treat infections, through localized delivery systems for antibiotics. [ABSTRACT FROM AUTHOR]

Electrolyte-gated organic field-effect transistors (EGOFETs) is a popular platform for numerous sensing and biosensing applications in aqueous media. In this work, the variation of electrical characteristics of EGOFETs based on small-molecule organic semiconductor C8-BTBT and polystyrene blend in water solutions at different pH values was investigated. A positive shift of the threshold voltage with near-Nernstian pH sensitivity was demonstrated in the pH range from 4.9 to 2.8, while no measurable pH dependence in the range from 4.9 to 8.6 pH was registered. These results indicate chemical doping of the molecules of organic semiconductors by protons from the electrolyte in the acidic region. In order to check the applicability of the EGOFETs in a flow mode, a flow chamber was designed and assembled. The preliminary results obtained in the flow mode measurements showed a fast response to pH variation. [ABSTRACT FROM AUTHOR]

Botanical extracts have potential for application in active food packaging systems in terms of antioxidant and antimicrobial activities, including other smart functions. In the present work, black sticky rice (Oryza sativa L.) extract (BE; 10 - 30%) was incorporated into a composite film of chitosan (1.0%) and methylcellulose (0.5, 1.0, and 1.5%), and prepared by a casting technique using polyethylene glycol (PEG 400) as a plasticiser. Application of 1.5% methylcellulose in combination with chitosan slightly increased film solubility and the water vapour permeability coefficient (WVPC), and improved physical properties as compared to other treatments. Film with a high BE content (20 - 30%) was thicker, and had a decreased WVPC. The tensile strength of the film increased in contrast to a statistically significant decrease (p = 0.05) in the percentage of elongation at break. The surface morphology of the film was flat and smooth, and the cross section was more rigid when viewed under a scanning electron microscope. The colour of the film containing 30% BE changed clearly from red (pH 1.0) to pinkish brown (pH 6.0) and finally yellow (pH 12.0), indicated by decreased a* value and increased b* value. ΔE presented the total colour difference that changed from an initial before immersing. The film was responsive when tested in food systems by mounting it on the lid of the box, showing a visible orangebrown colour in torpedo scad, greyish brown in chicken tenderloin, and light orange in minimally processed pineapple when foods spoiled. The present work revealed the potential of anthocyanin extract derived from purple sticky rice for use as a natural pH indicator in chitosan-methylcellulose-based films for intelligent packaging. [ABSTRACT FROM AUTHOR]

Fluorescein halogenated dyes are excellent photocatalysts for cross-dehydrogenation-coupled (CDC) reaction. In this paper, seven different halo-fluorescein dyes were selected to investigate the influence of heavy halogen atoms and proton concentrations on halo-fluoresceins for photocatalytic CDC reaction. The results showed that the heavy atoms directly affected intersystem crossing (ISC), which could act as a gatekeeper in the photoredox cycle and also affect photoinduced electron transfer (PET) process. Thus, the photocatalytic performance clearly increased in the following order: fluorescein FL (0.11 mol L−1•h−1)＜dibromo-fluorescein FL-2Br (0.19 mol L−1•h−1)＜diiodo-fluorescein FL-2I (0.29 mol L−1•h−1)＜tetrabromo-fluorescein FL-4Br (0.375 mol L−1•h−1)＜tetrabromo-tetrachloro-fluorescein FL-4Br–4Cl (0.53 mol L−1•h−1)＜tetraiodo-fluorescein FL-4I (0.58 mol L−1•h−1)＜ tetraiodo-tetrachloro-fluorescein FL-4I–4Cl (0.74 mol L−1•h−1). Furthermore, the visible light absorption of halogenated fluorescein dyes varied significantly with pH, thereby affecting their photocatalytic activity of CDC reaction. The dianionic FL-4I–4Cl could fully absorb light energy and exhibit excellent photocatalytic performance under mildly alkaline conditions (pH = 8), achieving a CDC reaction conversion rate of 99.92 %, which was 2.6 times higher than that of the lactone form of FL-4I–4Cl under acidic conditions (pH = 2). The halo-fluorescein dyes for photocatalytic CDC reaction. [Display omitted] • Halo-fluoresceins' heavy atom effect enhanced ISC and CDC photocatalysis. • pH-induced changes in halo-fluoresceins modulated photophysics and CDC photocatalytic efficiency. • A framework for halo-fluorescein photocatalyst design, highlighting pH and heavy atom effects. [ABSTRACT FROM AUTHOR]