pH Response Research Articles

Structure regulation of oxidized soybean cellulose nanocrystals/poly-acrylamide hydrogel and its application potential in wound dressing

The development of functional dressings based on natural polysaccharide-based hydrogels remains a great challenge, and the specific roles of gel composition and drug-controlled release mechanisms were unclear. In this study, oxidized soybean cellulose nanocrystals (CNCs)/poly-acrylamide (PAM) hydrogel was prepared. The proportion of CNCs, crosslinkers, and water in the system was regulated to fine-tune the rheological performances, texture properties, transparency, and micro-network structures of CNCs/PAM hydrogel, and further explored its application potential in the field of wound dressings. It was found that CNCs improved the rigidity and adhesion of hydrogels, crosslinkers improved the network density, and water promoted the softening and fluidity of hydrogels. The effective filling of CNCs in the composite hydrogel was verified by FTIR, XRD, and NMR. Furthermore, the pH responsiveness and drug-loading potential of the smart hydrogel were tested by swelling and drug-controlled release experiments, elucidating drug-release dynamic mechanisms during the wound healing process. The inhibition zones (>7 mm) of gram-positive/negative bacteria and cell viability (>100 %) assay showed satisfactory biocompatibility, as the hydrogel effectively accelerated wound healing in a wound model. These results elucidated the regulation mechanism of the structures of CNCs/PAM hydrogel and revealed the application potential of CNCs/PAM hydrogel in wound dressings.

Novel spiropyran fluorescent probes based on ESIPT and ICT: pH Response & Cyanide Detection

Novel spiropyran fluorescent probes based on ESIPT and ICT: pH Response & Cyanide Detection

Real-Time Monitoring of Seawater Quality Parameters in Ayia Napa, Cyprus

Real-time monitoring systems are crucial for the comprehensive management of operations and processes, as well as for assessing the impacts of coastal infrastructures on the marine environment. These systems not only support environmental protection and data-driven decision-making but also enable the early detection of adverse events and the issuance of timely warnings for prompt responses. Although water quality is a critical parameter in this monitoring framework, there are currently limited permanent systems in place dedicated to maintaining these objectives. Even fewer systems leverage their data for research purposes, leading to a gap in the literature regarding effective processing approaches for real-time water quality data. In this context, this study presents a real-time water quality monitoring system integrated into a broader in-field laboratory installed at a coastal area off the coast of Ayia Napa, Cyprus, as well as an initial measured data set of different qualitative quantities. It proposes a holistic approach for post-processing real-time seawater quality data, employing both time and frequency domain analyses, alongside filtering techniques. The study discusses the advantages of each method and emphasizes the importance of their combined use. Utilizing data collected from a three-month operational period, the study assesses the current state of marine seawater quality and examines both temporal and cyclic variations in various seawater quality parameters. The findings reveal that the examined seawater parameters are within reasonable values, indicating that the construction and operation of a nearby marina and the necessary infrastructures (e.g., breakwater) did not affect the seawater quality in the area. Additionally, the study identifies pronounced daily cyclic responses in different seawater quality parameters, including temperature, density, pH, dissolved oxygen, and turbidity. Finally, notable correlations are observed between temperature and dissolved oxygen, temperature and conductivity, oxidation–reduction potential (ORP) and salinity, ORP and dissolved oxygen, and ORP and TDS.

PH- and temperature-dual responsive polymer emulsion for rapid release of drag reducer

Slick water fracturing fluid is widely used in major oil fields due to its low cost and high drag reduction. Polyacrylamide emulsions drag reducers play a decisive role in slick water fracturing. The dissolution rate of polymer emulsions drag reducers was increased by adding hydrophilic surfactants, but the stability of the emulsions is poor, which limits its wide application. In order to solve the contradiction between the stability of polymer emulsion and rapid release of drag reducer. Here, a P(AA-AM-AMPS) polymer emulsion drag reducer with dual stimulation response of pH and temperature was designed. Surfactant (D400/OA) with dual responses to pH and temperature is synthesized by using oleic acid (HOA) and polyether amine 400 (D400). D400/OA shows a remarkable pH- and temperature-responsive behavior due to the pH- and temperature-induced structural transformation of D400/OA. Interestingly, D400/OA-stabilized monomer emulsion exhibits an obvious pH- and temperature-induced structural transformation. Meanwhile, The D400/OA-stabilized monomer emulsion has remarkable stability, which benefits the inverse emulsion polymerization of P(AM-AA-AMPS) polymer. The obtained P(AM-AA-AMPS) polymer emulsion maintain stability whose particle size nearly unchanged by storing for 15 days. Interestingly, P(AM-AA-AMPS) polymer emulsion can be released completely by changing the pH or temperature of the aqueous solution. The apparent viscosity of P(AM-AA-AMPS) polymer, in either the alkaline (pH=10.31) solution of 25±2 °C or neutral (pH=7) solution of 70±2 °C, respectively required 40 s and 8 min to reached a maximum value of 96 mPa·s. The release rate of P(AM-AA-AMPS) polymer emulsion is further enhanced under the dual responsive of temperature (70±2 ℃) and pH (10.31) and it takes only 20 s, In addition, the drag reduction rate of P(AM-AA-AMPS) polymer emulsion is 72 % when completely released under the dual responsive of temperature and pH, showing a remarkable drag reduction property. The D400/OA-stabilized P(AM-AA-AMPS) polymer emulsion are expected to meet the demand for the production enhancement of the oil and gas reservoirs.

Multi‐Level Wettability Patterned Porous Matrix for Advanced Optical Information Encryption

AbstractIn the rapidly evolving landscape of information security, the demand for optical encryption techniques based on wettability patterning, which allows decryption without sophisticated devices and complex procedures, is progressively increasing. However, conventional approaches based on binary wettability patterned surfaces impose significant constraints in their practical use for high‐level information security. Herein, a novel approach to optically encrypt information through multi‐level wettability patterning is introduced on a porous polymer matrix synthesized from vinyl methacrylate (VMA) and poly(ethylene glycol) diacrylate (PEGDA). By employing the thiol‐ene click reaction, precise patterning of functional groups is achieved that exhibit distinct wettability responses to aqueous solutions with varying surface tensions, as well as pH‐responsive and fluorescent markers. This multi‐level wettability system surpasses traditional binary hydrophilic/hydrophobic patterns by providing enhanced control over wettability states, resulting in higher‐level encryption of information. The integration of pH and fluorescence responsivity further elevates the complexity and security of the encrypted information, making it decipherable only under specific and controlled conditions. The innovative approach offers a highly secure, robust, and customizable encryption method, redefining the potential of optical encryption technologies.

Synergistic bactericidal effect of antimicrobial peptides and copper sulfide-loaded zeolitic imidazolate framework-8 nanoparticles with photothermal therapy

Antimicrobial resistance (AMR) has emerged as a significant threat to human health. Antimicrobial peptides (AMPs) have proven to be an effective strategy against antibiotic-resistant bacteria, given their capacity to swiftly disrupt microorganism membranes and alter cell morphology. A common limitation, however, lies in the inherent toxicity of many AMPs and their vulnerability to protease degradation within the body. Photothermal therapy (PTT) stands out as a widely utilized approach in combating antibiotic-resistant bacterial infections, boasting high efficiency and non-invasive benefits. To enhance the stability and antibacterial efficacy of AMPs, a novel approach involving the combination of AMPs and PTT has been proposed. This study focuses on the encapsulation of At10 (an AMP designed by our group), and copper sulfide nanoparticles (CuS NPs) within zeolitic imidazolate framework-8 (ZIF-8) to form nanocomposites (At10/CuS@ZIF-8). The encapsulated CuS NPs exhibit notable photothermal properties upon exposure to near-infrared radiation. This induces the cleavage of ZIF-8, facilitating the release of At10, which effectively targets bacterial membranes to exert its antibacterial effects. Bacteria treated with At10/CuS@ZIF-8 under light radiation exhibited not only membrane folding and intracellular matrix outflow but also bacterial fracture. This synergistic antibacterial strategy, integrating the unique properties of AMPs, CuS NPs, and pH responsiveness of ZIF-8, holds promising potential for widespread application in the treatment of bacterial infections.

Realizing the Rapid Release of Drag Reducers via pH-Induced Oil Phase Transition of Inverse Emulsion.

As a key component of slickwater fracturing fluids, emulsion drag reducers play a vital role. The dissolving capacity of traditional emulsion drag reducers is improved by adding hydrophilic surfactants, which leads to poor stability of the emulsion drag reducer. In order to eliminate the contradiction between stability and release of the emulsion drag reducer, here, pH-responsive polymer emulsion was fabricated using the switching solvent (HA) and white oil as the continuous phase. Monomer emulsions exhibit obvious pH-responsive behavior. This is because the deprotonation of HA by pH stimulation leads to a change in the oil-water ratio of the emulsion, thereby facilitating the demulsification of emulsion. The remarkable stability of the monomer emulsion benefits the preparation of inverse emulsion polymers (P(AM-AA-AMPS)). The obtained P(AM-AA-AMPS) polymer emulsion features remarkable stability even after 15 days of storage. Importantly, the P(AM-AA-AMPS) polymer was released from the emulsion efficiently by pH stimulation instead of introducing an extra hydrophilic surfactant, which confirmed the improvement of polymer release by pH stimulation. The viscosity of the P(AM-AA-AMPS) polymer aqueous solution reaches a maximum value of 96 mPa s within 80 s at a pH value of 9.2. The release efficiency of P(AA-AM-AMPS) polymer emulsion is increased by 33% in comparison with that of traditional polymer emulsion (2 min). The P(AM-AA-AMPS) emulsion demonstrated remarkable drag-reduction performance by achieving a drag-reduction rate of 73% at a concentration of 0.05 wt %. P(AM-AA-AMPS) polymer emulsion with pH responsiveness eliminates the contradiction between the stability and release of emulsion drag reducers. Research based on pH-responsive P(AM-AA-AMPS) polymer emulsion provides other ideas for the development of quickly dissolving and long-term storage drag reducers, which is helpful for the development of low-permeability oil and gas resources.

High Stability Hydrogel Magnetic Relaxation Switch Sensor Driven by pH for the Sensitive Detection of Cd2.

The traditional magnetic relaxation switching (MRS) sensors have excellent sensitivity, but their stability is poor because the magnetic relaxation signal is easily affected by the external magnetic field or environmental oxidation. In this study, a highly stable hydrogel bead-based MRS (Gel-MRS) sensor was established for the accurate and sensitive detection of Cd2+ in rice. A pH-responsive hydrogel bead was applied as a core element for the target stimulus and transverse relaxation signal transduction. The stability experiments showed that the transverse relaxation time (T2) change of the Gel-MRS sensor was one-seventh that of traditional magnetic nanoparticles under an external magnetic field and less than a fifth that of Fe2+/Fe3+ conversion in air. The excellent stability was due to the fact that T2 of the Gel-MRS sensor came from the swelling system mediated by pH rather than the traditional aggregation/dispersion or Fe2+/Fe3+ conversion of magnetic nanoparticles. In addition, the target Cd2+ could exclusively trigger a pH response of the hydrogel beads, altering the T2, thus resulting in excellent relaxation properties (R2 = 56.89) and pH responsiveness of the Gel-MRS sensor. The swelling process of the hydrogel beads followed quasi-second-order dynamics. The Gel-MRS sensor demonstrated a remarkable limit of detection as low as 0.009 ng/mL for Cd2+, with a linear range of 0.01-5 ng/mL. The excellent stability and sensitivity made the Gel-MRS sensor have great application potential in food and environmental detection.

Synthesis and characterization of pH-responsive sodium alginate/humic acid composite hydrogels for sustained drug release of l-ascorbic acid

Addressing the challenges of poor biocompatibility and degradability of artificial drug carriers and poor stability of natural monomer gels in the current pharmaceutical market, this study utilized green natural sodium alginate (SA) and humic acid (HA) as raw materials. SA/HA-Ca2+ hydrogel spheres were prepared using Ca2+ as a crosslinking agent and loaded with l-ascorbic acid (L-AA), and the drug-retardation study was conducted using the droplet method. Various analysis techniques confirmed the formation of a three-dimensional network structure through coordination between HA, SA, and Ca2+, resulting in hydrogel spheres with good thermal stability. Meanwhile, the drug-loading rate, swelling, and in vitro drug release of SA/HA-Ca2+ gel spheres were investigated. Results showed that the hydrogel spheres exhibited strong pH responsiveness and satisfactory pore structure favorable for the loading of L-AA. The solubility of the SA/HA-Ca2+ hydrogel in buffer solutions at pH = 1.4 and 7.4 was 1.7315 and 5.1235 g/g, respectively, while the swelling kinetics followed a second-order swelling kinetic equation; the maximum release of L-AA was 23.67 % and 82.64 %. The release profiles of L-AA from different drug-loaded gels conformed to Langmuir's quasi-primary and quasi-secondary kinetic models. In conclusion, this study provides a theoretical basis for achieving slow drug release using SA/HA-Ca2+.

Fabrication of pH-responsive whey protein/sodium alginate composite hydrogel beads for theaflavins

In this study, pH-responsive whey protein (WP)/sodium alginate (SA) composite hydrogel beads using the ionic gelation method were described and evaluated for their potential as delivery carriers for theaflavin (TF). Fourier transform infrared spectroscopy (FTIR) confirmed the interaction between WP and SA in the hydrogel beads is driven primarily by the strong intermolecular interactions, including hydrogen bonding and electrostatic attractions. The swelling ratio of the beads possesses good pH dependence and pH reversibility, effectively preventing the release of TF in the gastric environment. The encapsulation efficiency (EE) of TF in hydrogel beads ranged from 94.995 ± 0.03 to 95.709 ± 0.14, with a loading capacity (LC) of 27–34 mg/g. In in vitro digestion simulations, owing to the pH responsiveness, hydrogel beads released minimal TF throughout gastric digestion and were fully released in the intestine phase. Additionally, the release kinetics of TF from the beads were further examined in a simulated intestinal environment. These findings suggest that the hydrogel bead system is a promising carrier for encapsulating TF, offering a theoretical and experimental basis for its future application in the food industry.

HMNPs@PDA-GQDs-FA as carries of gambogic acid for inhibiting VX2 tumor cells

Ellipsoidal hollow magnetic nanoparticles (HMNPs) were first synthesized through a hydrothermal method and coated with SiO2 via the Stöber method, followed by template hydrothermal synthesis using C18TMS/TEOS volume ratio for silica-shell formation. Then, the core–shell structure was grafted with graphene quantum dots (GQDs), dopamine hydrochloride (PDA), and folic acid (FA) by amide reaction to obtain HMNPs@PDA-GQDs-FA. Transmission electron microscopy, X-ray photoelectron spectroscopy, fluorescence spectroscopy, and N2 adsorption/desorption analysis confirmed the successful construction of the HMNPs@PDA-GQDs-FA nanoscale carrier–cargo composite. The carrier HMNPs@PDA-GQDs-FA had improved loading (51.63 %) and higher release (47.18 %) of gambogic acid (GA) at an acidic pH (5.7) than the release (32.23 %) at an acidic pH (7.4), showing the pH response of PDA to the surrounding environment of tumor cells. Cytotoxicity test results showed that the cell survival rate was above 95 %, indicating that the carrier–cargo had low cytotoxicity. Cell lethality was greatly improved after loading GA, and the advantages of using FA-grafted HMNPs as a targeting ligand for tumor imaging were demonstrated by SPECT imaging analysis. These results showed that HMNPs@PDA-GQDs-FA had good biocompatibility and could be used for the treatment of VX2 tumors after loading GA.

Supramolecular assembly strategy of modified starch chains for achieving recyclable emulsion biocatalysis within a narrow pH range

Stimuli-responsive Pickering emulsions are promising in biocatalysis for their ease of product separation and emulsifier recovery. However, pH responsiveness, though simple and cost-effective, faces challenges in precise control and narrow transition ranges, limiting its use in enzymatic catalysis. Herein we introduced amorphous octenyl succinic anhydride-modified debranched starch chains (Am-OSA-St) to control emulsion properties within a pH range suitable for enzymatic catalysis. By adjusting the OSA group density and molecular weight, Am-OSA-St allowed emulsions to transition reversibly between pH 7.3 and 5.5 and enabled self-recycling through supramolecular self-assembly. Employing molecular dynamics simulations and physicochemical characterization, we elucidated the control mechanism of oil-water interfaces via the microstructure transformation of Am-OSA-St. The findings revealed that protonation of carboxylate groups disrupted the charge balance and polarity of starch chains, leading to strong electrostatic and van der Waals interactions that drove self-assembly. This entanglement caused starch chains in the aqueous phase to “drag” those at the oil-water interface, moving them into the aqueous phase and forming micelles. These micelles, with a hydrophobic interior and hydrophilic exterior, prevented re-adsorption. Testing with Candida antarctica Lipase B (CALB) and N-acetylneuraminic lyase showed that the pH-regulated emulsion system maintained excellent efficiency and cycling stability in mild conditions.

Three birds with one stone: ZIF-8@g-C3N4 nanosheets simultaneously enhance barrier property, active protection and UV aging resistance of epoxy coatings

In order to address the challenge of the epoxy coating’s limited ability to mitigate electrochemical reactions following metal corrosion as well as its susceptibility to degradation and aging under ultraviolet irradiation, ZIF-8 (ZIF=Zeolitic Imidazolate Framework) was modified on the surface of Graphite-like carbon nitride (g-C3N4) nanosheets by in-situ loading method to construct ZIF-8@g-C3N4 (ZCN) smart nanoparticles which exhibited an acidic pH response with releasing Zn2+ cations and imidazole molecules to achieve an 87.2 % corrosion inhibition efficiency on carbon steel within 5 h. Modified by ZCN, epoxy coating (ZCN/EP) retained high barrier property even after a 40-day immersion in a 3.5 wt% NaCl solution. Meanwhile, ZCN responded to pH changes from localized corrosion, releasing inhibitors and forming zinc oxide/zinc hydroxide and Fe-Im chelate to further impede corrosion progression. Furthermore, combining the ability to absorb and reflect/scatter UV radiation, ZCN provided excellent UV resistance for ZCN/EP coatings to maintain exceptional anti-corrosion after 300 h of UV exposure, as well as good surface characteristics and thermal–mechanical properties. This work provides a novel concept for developing long-lasting coatings with multifunctionality.

Fluorescent, pH, and UCST Responsive Polymer Nanomaterials for Treatment of Recurrent Miscarriage.

Recurrent miscarriage (RM), defined as three or more consecutive spontaneous miscarriages, affects many women of childbearing age. The pathological basis of RM is an imbalance in apoptosis, with the MDM2-p53 pathway playing a crucial role. In this study, we synthesized poly(6-acetoxyl-ε-caprolactone)-graft-(4-amino-benzimidazole) (PCCL-4-ABI) by modifying poly(6-acetoxyl-ε-caprolactone) (PCCL) with 4-amino-benzimidazole (4-ABI). The introduction of carboxyl and 4-ABI groups endowed the PCL backbone with fluorescence, pH responsiveness, and UCST responsiveness. The temperature-dependent release behavior of compound 1-loaded PCCL-4-ABI nanofluorescent materials was attributed to UCST transition. We successfully developed a novel nanofluorescent polymer drug delivery platform, PCCL-4-ABI@1, and evaluated its regulatory effects on p53 and MDM2 in trophoblast cells (HTR-8/SVneo). The results showed that the system loaded with low molecular weight heparin increased MDM2 and decreased p53 expression in a dose-dependent manner, thereby inhibiting trophoblast cell apoptosis. This study developed a biodegradable poly(ε-caprolactone) with UCST behavior, significant for the advancement of thermoresponsive fluorescent nanoparticle systems.

A Novel Approach for the Synthesis of Responsive Core-Shell Nanogels with a Poly(N-Isopropylacrylamide) Core and a Controlled Polyamine Shell.

Microgel particles can play a key role, e.g., in drug delivery systems, tissue engineering, advanced (bio)sensors or (bio)catalysis. Amine-functionalized microgels are particularly interesting in many applications since they can provide pH responsiveness, chemical functionalities for, e.g., bioconjugation, unique binding characteristics for pollutants and interactions with cell surfaces. Since the incorporation of amine functionalities in controlled amounts with predefined architectures is still a challenge, here, we present a novel method for the synthesis of responsive core-shell nanogels (dh < 100 nm) with a poly(N-isopropylacrylamide) (pNIPAm) core and a polyamine shell. To achieve this goal, a surface-functionalized pNIPAm nanogel was first prepared in a semi-batch precipitation polymerization reaction. Surface functionalization was achieved by adding acrylic acid to the reaction mixture in the final stage of the precipitation polymerization. Under these conditions, the carboxyl functionalities were confined to the outer shell of the nanogel particles, preserving the core's temperature-responsive behavior and providing reactive functionalities on the nanogel surface. The polyamine shell was prepared by the chemical coupling of polyethyleneimine to the nanogel's carboxyl functionalities using a water-soluble carbodiimide (EDC) to facilitate the coupling reaction. The efficiency of the coupling was assessed by varying the EDC concentration and reaction temperature. The molecular weight of PEI was also varied in a wide range (Mw = 0.6 to 750 kDa), and we found that it had a profound effect on how many polyamine repeat units could be immobilized in the nanogel shell. The swelling and the electrophoretic mobility of the prepared core-shell nanogels were also studied as a function of pH and temperature, demonstrating the successful formation of the polyamine shell on the nanogel core and its effect on the nanogel characteristics. This study provides a general framework for the controlled synthesis of core-shell nanogels with tunable surface properties, which can be applied in many potential applications.

A Urease-Based pH Photoswitch: A General Route to Light-to-pH Transduction.

New approaches for the integration of chemical and physical stimuli to control the dynamics of artificial enzymatic reaction networks (ERNs) are needed. Here, we present a general approach to convert a light stimulus into a time-programmed pH response. We developed and characterized a panel of photoswitchable inhibitors of urease. Urease activity, now regulated by light via the photoinhibitors, leads to an increase in pH upon hydrolysis of urea into ammonia. Careful choice of characteristics of light, and concentrations of enzyme, substrate, and photoinhibitor, allowed us to control the timing of the pH transition. Furthermore, as all enzymes have an activity-pH profile, the urease photoinhibitor system can be used to regulate the activities of other enzymes in small reaction networks.

A pH-responsive MOFs@MPN nanocarrier with enhancing antifungal activity for sustainable controlling myclobutanil release

The pH-responsive metal–organic framework (MOF) nanocarriers for sustainable controlled release of pesticides is promising in agricultural production owing to their long duration, high loading efficiency and antimicrobial activity. In this work, myclobutanil (MYC) was loaded into an Ag-based MOF (Ag-TCPP), and modified with a metal-phenolic network (MPN) via in-situ polymerization to construct a pH-responsive nano-delivery system (Ag-TCPP@MYC@MPN). Ag-TCPP@MYC@MPN presented a disordered nanoflower structure and many active sites with potential enhanced loading activity. The cumulative release rates of nanoparticles at pH 4.96, 7.5, and 8.5 were 52.6 %, 62.6 % and 80.0 %, respectively. Hence, Ag-TCPP@MYC@MPN has slow release rate and pH responsiveness. The antifungal activity of Ag-TCPP@MYC@MPN was significantly enhanced, and the bacteriostatic rate reached 81.8 %. This enhancement may be attributed to the synergistic antibacterial effect between tannic acid and Ag+. Safety experiments showed the nanoparticles had no inhibitory effect on the germination of Pakchoi seeds, and the pesticide residues of Ag-TCPP@MYC@MPN did not exceed the food safety standards. This work offers a new potential to develop improved responsive stimulus nanocarriers for sustainable controlled release of MYC.

Carboxymethyl chitosan-dialdehyde glucan/polydopamine carrier targeted delivery Bacillus subtilis on enhancing oral utilization and intestinal colonization in mice

Most probiotics are difficult to resist the invasion of gastrointestinal physiological and pathological environments, which limits their beneficial effects. The design of a pH-responsive and adhesive double-layer carrier (Carboxymethyl chitosan polyaldehyde polysaccharide, CMCS-DHG/PDA) aims to safeguard the activity of probiotics and enhance their intestinal colonization. The results obtained from UV–vis spectroscopy and XPS analysis revealed the formation of a polydopamine nanocoating surrounding Bacillus subtilis, and the outer carrier formed a Schiff base covalent bond, providing sufficient mechanical properties for the carrier. The carrier exhibited a significantly higher degree of swelling under pH 1.2 compared to pH 7.4, indicating its pronounced pH responsiveness. The CMCS-DHG/PDA carrier not only provided protection for B. subtilis against simulated digestive fluids, but also improved its tolerance to bile and antibiotics. In addition, carrier-protected probiotics showed extraordinary mucosal adhesion, which could significantly improve oral bioavailability and intestinal colonization. Finally, the impact of carrier-protected B. subtilis on gut microbiota was explored, revealing that the carrier protected B. subtilis could significantly improve the diversity, richness, and composition of gut microbiota. Concurrently, it promoted the formation of short chain fatty acids, creating a more beneficial environment for intestinal health.

Development of a 3D Hydrogel SERS Chip for Noninvasive, Real-Time pH and Glucose Monitoring in Sweat.

Traditional diagnostic methods, such as blood tests, are invasive and time-consuming, while sweat biomarkers offer a rapid physiological assessment. Surface-enhanced Raman spectroscopy (SERS) has garnered significant attention in sweat analysis because of its high sensitivity, label-free nature, and nondestructive properties. However, challenges related to substrate reproducibility and interference from the biological matrix persist with SERS. This study developed a novel ratio-based 3D hydrogel SERS chip, providing a noninvasive solution for real-time monitoring of pH and glucose levels in sweat. Encapsulating the probe molecule (4-MBN) in nanoscale gaps to form gold nanoflower-like nanotags with internal standards and integrating them into an agarose hydrogel to create a 3D flexible SERS substrate significantly enhances the reproducibility and stability of sweat analysis. Gap-Au nanopetals modified with probe molecules are uniformly dispersed throughout the porous hydrogel structure, facilitating the effective detection of the pH and glucose in sweat. The 3D hydrogel SERS chip demonstrates a strong linear relationship in pH and glucose detection, with a pH response range of 5.5-8.0 and a glucose detection range of 0.01-5 mM, with R2 values of 0.9973 and 0.9923, respectively. In actual sweat samples, the maximum error in pH detection accuracy is only 1.13%, with a lower glucose detection limit of 0.25 mM. This study suggests that the ratio-based 3D hydrogel SERS chip provides convenient, reliable, and rapid detection capabilities with substantial application potential for analyzing body fluid pH and glucose.

Bacterial Cellulose Incorporating Multicolor Fluorescent Probes for Visual Acidity Detection in Paper-Based Cultural Relics.

Paper-based cultural relics often undergo acidification and deterioration during long-term preservation. Accurate detection of paper acidity is of great significance to assess aging status and extend the preservation lifetime of paper-based cultural relics. Rapid identification of the acidification degree and acid distribution across multiple regions of paper is essential. Inspired by fluorescent sensing technology, pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) and rhodamine B (RB) fluorescent probes are synthesized and incorporated onto the nanofibers of a bacterial cellulose (BC) membrane to enable visual acidity detection of paper. Due to the complementary pH detection range of CdTe QDs and RB probes, the composite BC membrane exhibits a clear pH response across an acidic to neutral range (pH 3.0-7.5). Notably, the contrasting fluorescent colors of the two probes within the BC membrane allow for easy visualization of paper pH and acidity distribution with the naked eyes. A distinct color transition from red to green was observed on the fluorescent BC membrane when it is applied to a model paper with a gradient pH distribution. The feasibility of this method was verified by using the flat-headed pH electrode method. Additionally, common metal ions in most paper fillers, inks, pigments, as well as some sugars and amino acids showed minimal interference with the pH response of the composite BC membrane, highlighting its potential and broad applicability for visual acidity detection in paper-based cultural relics.