pH

Overview

pH is a logarithmic measure of hydrogen ion activity in solution and a fundamental physicochemical parameter in chemistry, biology, medicine, and pharmaceutical science. It reflects acidity or alkalinity and strongly influences molecular charge, protein conformation, membrane stability, enzyme activity, microbial growth, drug solubility, and colloidal behavior. In biological systems, pH is tightly regulated across compartments such as blood, gastric fluid, cerebrospinal fluid, and intracellular organelles, where even modest shifts can alter physiology and disease processes.

In biomedical research, pH is often treated as both a variable and a targetable environmental cue. Acidic or alkaline conditions can be exploited in drug delivery systems, wound diagnostics, nanomedicine, and biosensors, including platforms based on liposome, chitosan gel, carbon quantum dots, and aptamer-based electrochemical biosensors. pH also interacts with related factors such as buffer capacity, serum calcium, cations, Amino Acids, and temperature, shaping formulation stability and biological responses in settings ranging from cancer immunotherapy to food preservation and environmental microbiology.

Focus of Latest Publications

Recent studies have used pH as a central determinant of material behavior, microbial ecology, diagnostic performance, and therapeutic design.

In environmental science, pH was described as part of the physicochemical context governing microbial adaptation in extreme habitats such as salt flats, tropical glaciers, volcanoes, and Andean deserts, where salinity, temperature, radiation, low water activity, nutrient limitation, and heavy metal exposure converge. In soil colloid research, transient increases in pH, together with reduced ionic strength, lowered energy barriers for detachment of reversibly retained Pd-NPs from nanoscale roughness sites, facilitating remobilization of nanoplastics-associated particles. Another environmental study reported that formic and acetic acids reduced aerosol pH through hydrogen-ion activity effects, illustrating how pH can be shifted by organic acids in atmospheric systems. In wastewater treatment, lower pH increased N₂O production during aeration by heterotrophic denitrification, while thermophilic biodegradation studies optimized pH alongside temperature, incubation time, medium volume, inoculum size, and substrate concentration to improve phenol-catechol removal. Groundwater quality classification models also included pH among key regulatory indicators.

In microbiology and fermentation, pH repeatedly emerged as a driver of community structure and metabolite production. Pit mud archaeal communities in strong-flavor Baijiu were associated with pH and other environmental factors such as humus, ammonium nitrogen, available phosphorus, and metal elements. In fermented dough, pH dropped to 4.13 during co-culture of Kluyveromyces marxianus and Lactiplantibacillus plantarum, coinciding with increased titratable acidity and water-holding capacity. In mushroom and wine precursor studies, pH was identified as a main factor affecting fungal biosynthesis of free and glycosylated compounds at the prefermentative stage. In anaerobic digestion of food waste, volatile fatty acid accumulation drove pH down to approximately 7, inhibiting methanogenic activity and contributing to process failure. Food preservation studies likewise tracked pH as a spoilage-related indicator: smoked gelatin lowered pH in emulsified sausage, ginsenosides attenuated pH increases in beef, and antibacterial hydrogel packaging delayed pH changes during storage of prefabricated meat.

In pharmaceutical formulation and drug delivery, pH was a major control parameter for stability, loading, release, and structural transitions. Setmelanotide loading into PLGA microspheres was reported to be pH-dependent because ion pairing and polymer proton exchange altered the polymer environment. Chrysophanol release from polycaprolactone/xanthan gum microparticles was sensitive to pH, and ascorbic acid-loaded chitosan nanoparticles were optimized across pH 3, 4, and 5. Mesalamine dissolution behavior depended on pH, molarity, and buffer capacity, emphasizing the need for discriminatory dissolution methods. Insulin eye drops showed stable pH during storage, while sodium hypochlorite solutions used in root canal treatment were evaluated for time-dependent changes in pH and active chlorine content. In peptide and antibody research, liquid buffer pH influenced GLP-1 analog oligomerization, and empasiprubart showed calcium- and pH-dependent binding to complement component C2, suggesting functional differences between blood and endosomal environments. pH also affected complement-related and cancer-related bioengineering approaches, including bio-inspired nanoplatforms and cancer immunotherapy strategies that leverage acidic tumor microenvironments.

In biomaterials and colloid science, pH controlled electrostatic interactions, aggregation, and interfacial behavior. soy protein isolate/sodium carboxymethyl cellulose complexes became larger at lower pH, especially below pH 3.0, due to enhanced electrostatic interactions and coacervate formation. Ulva polysaccharide and soy protein isolate complexes showed pH-dependent phase behavior and gel properties, while ovalbumin/gum arabic emulsions changed fractal dimension as pH shifted from neutral to acidic. Coprinus comatus protein-polysaccharide complexes exhibited pH-driven conformational changes that regulated emulsifying properties. High internal phase emulsions stabilized by octenyl succinic acid soy hull polysaccharides were pH-responsive, with acidic conditions promoting molecular flexibility and lowering interfacial tension. Similar pH-dependent stability was reported for gelatin-based emulsions, triterpenoid-stabilized nanocages, and elastin-like polypeptide scaffolds. Molecular dynamics simulations and atomic force microscopy were used to connect pH-dependent structural remodeling with nanoscale mechanics.

In diagnostics and sensing, pH was incorporated into multiplexed monitoring systems and smart materials. A neonatal colorimetric sensor was calibrated across a pH range of 3–9, and a battery-free wireless oral aligner monitored compartment-matched pH and nitrite for chronic oral disease theranostics. A platform for cerebrospinal fluid monitoring included pH among near real-time biomarkers, and a soft robotic minitablet used a pH-sensitive hydrogel for ultrasound-based gastric pH readout across a physiologically relevant range of 2 to 7. Carbon quantum dots were combined into fluorescent chemical sensors with complementary responses to pH, tea polyphenols, and Amino Acids, enabling vintage discrimination of dark tea. In wound care, dynamic pH fluctuations were described as predictors of infection progression and healing prognosis, supporting the use of pH as a biomarker in artificial intelligence-driven wound theranostics.

Overall, these studies show that pH is not merely a background variable but a mechanistic determinant of microbial ecology, formulation stability, interfacial chemistry, and disease-associated microenvironments. Its interactions with temperature, buffer capacity, cations, Amino Acids, serum calcium, and related biomaterials such as liposome, chitosan gel, and BEO-lip are central to both experimental design and translational application.

Key Publications

• Jul Mechanisms of Long-Term Nanoplastic Release in Soil and Their Interaction with Soil Colloids. (Environmental science & technology, 2026, PMID 42313107): "However, transient changes in solution chemistry (e.g., increased pH and reduced ionic strength, IS) lowered energy barriers to detachment on some convex nanoscale roughness locations, facilitating remobilization of reversibly retained Pd-NPs."
• Jun Rare Worlds, Rare Microbes-From Salt Flats and Tropical Glaciers to Volcanoes and Andean Deserts as Natural Laboratories for Microbial Biotechnology in Latin America. (Environmental microbiology, 2026, PMID 42219550): "Instead, these ecosystems are characterized by the convergence of salinity, temperature, pH, radiation, low water activity, nutrient limitation, and high heavy metal concentrations, selecting for microbial communities with remarkable physiological plasticity and metabolic versatility."
• Jun Nanomedicine in precision treatment of gastric cancer: current clinical landscape. (Molecular biology reports, 2026, PMID 42228196): "We discuss how unique pathological features of the GC microenvironment such as hypoxia, acidity, and dense stroma-are leveraged to design "smart" stimuli-responsive nanoplatforms for precise drug delivery."
• May Artificial Intelligence-Supported Colorimetric Multibiomarker Sensor to Enable Critical Neonatal Monitoring. (ACS sensors, 2026, PMID 42205010): "Colorimetric responses showed high precision and reproducibility in sensing ranges relevant for neonatal care (T: 32-41 [°C]; pH: 3-9; S: 2.92-29.20 [mg/mL], G: 0.039-0.625 [mg/mL])."
• Jun A battery-free wireless intelligent aligner for spatially resolved, closed-loop theranostics of chronic oral diseases. (Science advances, 2026, PMID 42341135): "...to simultaneously monitor compartment-matched pH and nitrite and electrochemically gate on-demand antimicrobial release."
• Jun The role of pH changes during remote loading of setmelanotide in PLGA microspheres. (International journal of pharmaceutics, 2026, PMID 42070740): "However, this ion pairing loading technique also can be pH-dependent owing to the exchange of polymer protons with the peptide and the resulting pH effects on the polymer (and potentially peptide)."
• Jun Microparticles Based on Polycaprolactone, Xanthan Gum, and Chrysophanol: Optimization, Characterization, Bioactivities, Drug Release Performance, and Release Mechanism Insight. (Langmuir : the ACS journal of surfaces and colloids, 2026, PMID 42258705): "The CHR release process from these particles is also sensitive to pH and can be controlled by the interaction of the drug with polymer matrices."
• Jun Origin of Fresh Mushroom Off-Flavor Markers in Musts and Wines: Linoleic Acid and Glycosidic Precursors as Two Potential Reservoirs. (Journal of agricultural and food chemistry, 2026, PMID 42240412): "Finally, linoleic acid content (P. crocicola) and pH (P. crocicola, B. cinerea) were identified as the main factors impacting free and glycosylated compounds biosynthesis by fungi at the prefermentative stage."
• Jun Artificial Intelligence-Driven Janus Dressing for Visual Wound Theranostics. (ACS nano, 2026, PMID 42228941): "dynamic pH fluctuations serve as a key predictor of infection progression and healing prognosis."
• Jun Stability of the two enveloped viruses NDV LaSota and YF-ZIKprM/E to support process development. (PloS one, 2026, PMID 42296128): "Therefore, temperature and pH stability were tested as important parameters during upstream processing and freeze-thaw cycles were tested in context of laboratory-analytics."