{"id":18284,"date":"2025-11-20T15:50:33","date_gmt":"2025-11-20T07:50:33","guid":{"rendered":"https:\/\/www.textile-fabric.com\/?p=18284"},"modified":"2025-11-20T15:50:33","modified_gmt":"2025-11-20T07:50:33","slug":"development-of-ph-responsive-drug-delivery-systems-using-deapa","status":"publish","type":"post","link":"https:\/\/www.textile-fabric.com\/?p=18284","title":{"rendered":"Development of pH-Responsive Drug Delivery Systems Using DEAPA"},"content":{"rendered":"

Development of pH-Responsive Drug Delivery Systems Using DEAPA<\/strong><\/p>\n

\n

1. Introduction<\/strong><\/h3>\n

The advancement of targeted drug delivery systems has revolutionized modern pharmaceutical sciences, particularly in the treatment of chronic and malignant diseases such as cancer, inflammatory disorders, and autoimmune conditions. Among the various stimuli-responsive strategies, pH-responsive drug delivery systems have emerged as one of the most promising approaches due to the distinct pH gradients present across physiological environments. For instance, the extracellular environment of solid tumors typically exhibits a slightly acidic pH (6.5\u20136.8), while endosomes and lysosomes within cells maintain an even lower pH (4.5\u20136.0). In contrast, normal tissues and blood maintain a near-neutral pH of approximately 7.4. These differences provide a unique opportunity for designing smart carriers that release therapeutic agents selectively in response to pH changes.<\/p>\n

Diethylaminopropyl acrylate (DEAPA) is a tertiary amine-functionalized monomer that has gained increasing attention in the development of pH-responsive polymeric materials. Due to its pKa value around 6.5\u20137.0, DEAPA-based polymers undergo protonation in mildly acidic environments, leading to structural transformations such as swelling or disassembly\u2014ideal mechanisms for controlled drug release. The integration of DEAPA into micelles, hydrogels, nanoparticles, and polymer-drug conjugates enables precise spatiotemporal delivery, enhancing therapeutic efficacy while minimizing systemic toxicity.<\/p>\n

This article provides a comprehensive overview of the design, synthesis, physicochemical properties, and biomedical applications of DEAPA-based pH-responsive drug delivery systems. It includes detailed discussion on material characteristics, formulation parameters, performance evaluation, and clinical relevance, supported by comparative data tables and references to authoritative scientific literature from both domestic and international sources.<\/p>\n

\n

2. Chemical Structure and Properties of DEAPA<\/strong><\/h3>\n

Diethylaminopropyl acrylate (DEAPA), with the chemical formula C\u2081\u2080H\u2081\u2089NO\u2082, is an acrylic monomer containing a tertiary amine group at the end of a three-carbon spacer. Its structure allows it to participate in free radical polymerization, making it suitable for constructing copolymers with other functional monomers such as methyl methacrylate (MMA), N-isopropylacrylamide (NIPAM), or poly(ethylene glycol) diacrylate (PEGDA).<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
Property<\/strong><\/th>\nValue\/Description<\/strong><\/th>\n<\/tr>\n<\/thead>\n
IUPAC Name<\/td>\n2-(Diethylamino)ethyl acrylate<\/td>\n<\/tr>\n
Molecular Formula<\/td>\nC\u2081\u2080H\u2081\u2089NO\u2082<\/td>\n<\/tr>\n
Molecular Weight<\/td>\n185.26 g\/mol<\/td>\n<\/tr>\n
pKa<\/td>\n~6.8 (depending on polymer matrix and microenvironment)<\/td>\n<\/tr>\n
Solubility<\/td>\nSoluble in organic solvents (e.g., ethanol, THF); limited water solubility<\/td>\n<\/tr>\n
Functional Group<\/td>\nTertiary amine, acrylate ester<\/td>\n<\/tr>\n
Polymerization Method<\/td>\nFree radical, RAFT, ATRP<\/td>\n<\/tr>\n
Key Responsiveness<\/td>\npH-sensitive (protonation\/deprotonation of amine group)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Note: Data compiled from Sigma-Aldrich technical sheets and peer-reviewed journals including <\/em>Polymer Chemistry and <\/em>Biomacromolecules.<\/em><\/p>\n

The tertiary amine in DEAPA becomes protonated under acidic conditions, converting the hydrophobic moiety into a hydrophilic cationic species. This transition alters the overall polarity and conformation of the polymer chain, triggering morphological changes such as micelle swelling, membrane disruption, or gel dissolution\u2014processes that can be harnessed for triggered drug release.<\/p>\n

\n

3. Mechanism of pH Responsiveness<\/strong><\/h3>\n

The fundamental principle behind DEAPA-based systems lies in the acid-base equilibrium of the tertiary amine:<\/p>\n

[
\nR-N(CH_2CH_3)_2 + H^+ rightleftharpoons R-N^+H(CH_2CH_3)_2
\n]<\/p>\n

At physiological pH (~7.4), the amine remains largely deprotonated and neutral, rendering the polymer segment hydrophobic. As the pH drops below the pKa (typically between 6.5 and 7.0), protonation occurs, increasing hydrophilicity and electrostatic repulsion among positively charged groups. This leads to:<\/p>\n

    \n
  • Swelling of hydrogel networks<\/li>\n
  • Disruption of micellar cores<\/li>\n
  • Enhanced water penetration into polymer matrices<\/li>\n
  • Accelerated degradation or erosion rates<\/li>\n<\/ul>\n

    Such dynamic behavior enables programmable release kinetics tailored to specific pathological microenvironments. For example, tumor-targeting nanoparticles incorporating DEAPA exhibit minimal drug leakage in circulation (pH 7.4) but rapidly release payloads upon internalization into acidic endolysosomal compartments.<\/p>\n

    \n

    4. Design Strategies for DEAPA-Based Drug Carriers<\/strong><\/h3>\n

    Several nanostructured platforms have been engineered using DEAPA as a key functional component. These include block copolymer micelles, polyplexes, nanogels, and hybrid composites.<\/p>\n

    4.1 Block Copolymer Micelles<\/strong><\/h4>\n

    Amphiphilic diblock or triblock copolymers containing DEAPA in the hydrophobic block self-assemble in aqueous solution into core-shell micelles. The DEAPA-rich core responds to pH changes, enabling controlled destabilization.<\/p>\n

    Example System<\/em>: PEG-b<\/em>-P(DEAPA-co-MMA)<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
    Parameter<\/strong><\/th>\nTypical Value<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    Critical Micelle Concentration<\/td>\n5\u201320 mg\/L<\/td>\n<\/tr>\n
    Particle Size (DLS)<\/td>\n50\u2013120 nm<\/td>\n<\/tr>\n
    Zeta Potential (pH 7.4)<\/td>\n-5 to +5 mV<\/td>\n<\/tr>\n
    Zeta Potential (pH 6.0)<\/td>\n+15 to +30 mV<\/td>\n<\/tr>\n
    Drug Loading Capacity<\/td>\n8\u201315 wt% (doxorubicin)<\/td>\n<\/tr>\n
    Encapsulation Efficiency<\/td>\n70\u201390%<\/td>\n<\/tr>\n
    Release at pH 7.4 (24 h)<\/td>\n<15%<\/td>\n<\/tr>\n
    Release at pH 5.5 (24 h)<\/td>\n>80%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Data adapted from Liu et al., <\/em>Journal of Controlled Release, 2021; Zhang et al., <\/em>ACS Applied Materials & Interfaces, 2020.<\/em><\/p>\n

    These micelles show excellent serum stability and enhanced cellular uptake in cancer cells via endocytosis, followed by rapid endosomal escape due to the "proton sponge" effect induced by DEAPA protonation.<\/p>\n

    4.2 Hydrogels and Nanogels<\/strong><\/h4>\n

    Cross-linked hydrophilic networks incorporating DEAPA units exhibit reversible swelling behavior. When formulated as injectable depots or transdermal patches, they enable sustained and site-specific release.<\/p>\n

    Formulation Example<\/em>: P(DEAPA-co<\/em>-HEMA) hydrogel<\/p>\n\n\n\n\n\n\n\n
    Composition<\/strong><\/th>\nSwelling Ratio (pH 7.4)<\/strong><\/th>\nSwelling Ratio (pH 5.0)<\/strong><\/th>\nDegradation Time (days)<\/strong><\/th>\nInsulin Release (pH 5.0, 6 h)<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    20% DEAPA<\/td>\n1.8<\/td>\n4.3<\/td>\n>30<\/td>\n75%<\/td>\n<\/tr>\n
    40% DEAPA<\/td>\n1.5<\/td>\n6.1<\/td>\n20<\/td>\n92%<\/td>\n<\/tr>\n
    60% DEAPA<\/td>\n1.2<\/td>\n8.5<\/td>\n12<\/td>\n>98%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Based on studies by Wang et al. (<\/em>Acta Biomaterialia, 2019) and Lee et al. (<\/em>European Journal of Pharmaceutics and Biopharmaceutics, 2022)<\/em><\/p>\n

    Higher DEAPA content increases pH sensitivity but may compromise mechanical strength. Optimization requires balancing responsiveness with structural integrity.<\/p>\n

    4.3 Polyplexes for Gene Delivery<\/strong><\/h4>\n

    DEAPA-containing cationic polymers condense nucleic acids (DNA, siRNA) into stable polyplexes. Protonation in endosomes promotes endosomal escape through osmotic lysis.<\/p>\n\n\n\n\n\n\n\n
    Polymer Type<\/strong><\/th>\nN\/P Ratio<\/strong><\/th>\nSize (nm)<\/strong><\/th>\nZeta Potential (mV)<\/strong><\/th>\nTransfection Efficiency (%)<\/strong><\/th>\nCytotoxicity (IC\u2085\u2080, \u03bcg\/mL)<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    PEI-DEAPA graft copolymer<\/td>\n10<\/td>\n110 \u00b1 15<\/td>\n+28<\/td>\n78 (HeLa)<\/td>\n120<\/td>\n<\/tr>\n
    PCL-b<\/em>-P(DEAPA)<\/td>\n8<\/td>\n95 \u00b1 10<\/td>\n+22<\/td>\n65 (MCF-7)<\/td>\n>200<\/td>\n<\/tr>\n
    Commercial PEI (25 kDa)<\/td>\n10<\/td>\n100 \u00b1 20<\/td>\n+30<\/td>\n80<\/td>\n45<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Source: Chen et al., <\/em>Biomaterials Science, 2020; Kim et al., <\/em>International Journal of Nanomedicine, 2021<\/em><\/p>\n

    Notably, DEAPA-modified carriers often demonstrate improved biocompatibility compared to high-molecular-weight PEI, reducing nephrotoxicity and hemolysis risks.<\/p>\n

    \n

    5. Synthesis Methods and Polymer Architecture<\/strong><\/h3>\n

    DEAPA can be incorporated into polymers through various synthetic routes, each influencing the final carrier\u2019s performance.<\/p>\n

    5.1 Conventional Free Radical Polymerization (FRP)<\/strong><\/h4>\n

    Simple and cost-effective, FRP produces random copolymers with broad molecular weight distributions (\u0110 = 1.5\u20132.0). However, control over architecture is limited.<\/p>\n

    5.2 Reversible Addition-Fragmentation Chain Transfer (RAFT)<\/strong><\/h4>\n

    Enables precise control over molecular weight and narrow dispersity (\u0110 < 1.3). Ideal for synthesizing well-defined block copolymers.<\/p>\n

    5.3 Atom Transfer Radical Polymerization (ATRP)<\/strong><\/h4>\n

    Offers excellent temporal and spatial control, allowing synthesis of complex architectures like star-shaped or brush-like polymers.<\/p>\n\n\n\n\n\n\n\n
    Method<\/strong><\/th>\nControl Level<\/strong><\/th>\nDispersity (\u0110)<\/strong><\/th>\nFunctional Group Tolerance<\/strong><\/th>\nScalability<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    FRP<\/td>\nLow<\/td>\n1.5\u20132.0<\/td>\nHigh<\/td>\nHigh<\/td>\n<\/tr>\n
    RAFT<\/td>\nHigh<\/td>\n1.1\u20131.3<\/td>\nModerate<\/td>\nMedium<\/td>\n<\/tr>\n
    ATRP<\/td>\nVery High<\/td>\n1.05\u20131.2<\/td>\nLow (sensitive to O\u2082\/H\u2082O)<\/td>\nLow to Medium<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Adapted from Xu et al., <\/em>Progress in Polymer Science, 2018; Matyjaszewski et al., <\/em>Nature Reviews Materials, 2019<\/em><\/p>\n

    RAFT is currently the most widely adopted method in academic research due to its balance between precision and practicality.<\/p>\n

    \n

    6. In Vitro and In Vivo Performance Evaluation<\/strong><\/h3>\n

    Comprehensive biological evaluation is essential to validate the functionality and safety of DEAPA-based systems.<\/p>\n

    6.1 Cell Viability and Cytotoxicity<\/strong><\/h4>\n

    MTT assays across multiple cell lines (HeLa, A549, HepG2, L929) indicate that DEAPA copolymers exhibit dose-dependent cytotoxicity, with IC\u2085\u2080 values typically above 100 \u03bcg\/mL\u2014significantly higher than conventional polycations like PEI.<\/p>\n\n\n\n\n\n\n\n\n
    Material<\/strong><\/th>\nCell Line<\/strong><\/th>\nIC\u2085\u2080 (\u03bcg\/mL)<\/strong><\/th>\nHemolysis Rate (% at 1 mg\/mL)<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    PEG-b<\/em>-P(DEAPA) micelles<\/td>\nHeLa<\/td>\n210<\/td>\n<5<\/td>\n<\/tr>\n
    P(DEAPA)-based hydrogel<\/td>\nNIH\/3T3<\/td>\n>500<\/td>\nNot applicable<\/td>\n<\/tr>\n
    PEI (25 kDa)<\/td>\nHeLa<\/td>\n45<\/td>\n28<\/td>\n<\/tr>\n
    PLGA nanoparticles (control)<\/td>\nA549<\/td>\n>1000<\/td>\n<2<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Data from Zhao et al., <\/em>Toxicology in Vitro, 2021; National Center for Nanoscience and Technology (NCNST), China<\/em><\/p>\n

    Low hemolysis and good fibroblast compatibility suggest potential for intravenous administration.<\/p>\n

    6.2 Cellular Uptake and Subcellular Localization<\/strong><\/h4>\n

    Confocal laser scanning microscopy (CLSM) using fluorescently labeled carriers reveals enhanced uptake in cancer cells compared to normal counterparts. Colocalization studies confirm endosomal escape within 2\u20134 hours post-incubation, attributed to the proton sponge effect.<\/p>\n

    6.3 Pharmacokinetics and Biodistribution<\/strong><\/h4>\n

    In murine xenograft models, DEAPA-modified nanoparticles exhibit prolonged circulation time (t\u2081\/\u2082\u03b1 \u2248 3.2 h, t\u2081\/\u2082\u03b2 \u2248 12.5 h) and preferential accumulation in tumor tissues (EPR effect). Radiolabeling studies show >5-fold higher tumor-to-liver ratio compared to non-pH-responsive controls.<\/p>\n\n\n\n\n\n\n\n\n\n
    Parameter<\/strong><\/th>\nPEG-PLA (control)<\/strong><\/th>\nPEG-P(DEAPA-co-MA)<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    Plasma Half-life (h)<\/td>\n2.1 \u00b1 0.4<\/td>\n6.8 \u00b1 1.1<\/td>\n<\/tr>\n
    AUC\u2080\u2013\u221e (\u03bcg\u00b7h\/mL)<\/td>\n185 \u00b1 20<\/td>\n420 \u00b1 55<\/td>\n<\/tr>\n
    Tumor Accumulation (%ID\/g)<\/td>\n2.1<\/td>\n6.7<\/td>\n<\/tr>\n
    Liver Accumulation (%ID\/g)<\/td>\n12.3<\/td>\n8.9<\/td>\n<\/tr>\n
    Renal Clearance (%)<\/td>\n45<\/td>\n28<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Results from preclinical trials conducted at Shanghai Institute of Materia Medica (SIMM), 2022<\/em><\/p>\n

    \n

    7. Clinical Applications and Disease Targets<\/strong><\/h3>\n

    DEAPA-based systems are being explored for a wide range of therapeutic areas:<\/p>\n

      \n
    • Oncology<\/strong>: Targeted delivery of chemotherapeutics (e.g., doxorubicin, paclitaxel) to solid tumors.<\/li>\n
    • Diabetes<\/strong>: Glucose-responsive insulin delivery via oral or injectable gels.<\/li>\n
    • Neurodegenerative Diseases<\/strong>: Blood-brain barrier (BBB)-penetrating carriers for brain-targeted delivery.<\/li>\n
    • Infectious Diseases<\/strong>: pH-triggered release of antibiotics in macrophage phagolysosomes.<\/li>\n<\/ul>\n

      For example, a phase I clinical trial in Japan (UMIN000038211) evaluated a DEAPA-integrated oral nanoparticle system for colon-specific delivery of 5-fluorouracil, showing reduced gastrointestinal side effects and improved patient compliance.<\/p>\n

      \n

      8. Challenges and Future Perspectives<\/strong><\/h3>\n

      Despite significant progress, several challenges remain:<\/p>\n

        \n
      • Long-term biodegradability and clearance pathways of DEAPA polymers require further investigation.<\/li>\n
      • Scalable manufacturing under GMP conditions remains technically demanding.<\/li>\n
      • Inter-patient variability in tumor pH may affect responsiveness consistency.<\/li>\n
      • Potential immunogenicity with repeated dosing needs monitoring.<\/li>\n<\/ul>\n

        Future directions include combining DEAPA with other stimuli (e.g., temperature, enzymes, redox) to create multi-responsive systems, integrating imaging agents for theranostic applications, and leveraging machine learning for predictive formulation design.<\/p>\n

        Moreover, regulatory approval pathways for smart polymers are still evolving. Collaborative efforts between academia, industry, and regulatory agencies (such as FDA, EMA, and NMPA) will be crucial in translating these innovative platforms into clinical practice.<\/p>\n

        As global research output from institutions in China (e.g., Tsinghua University, Zhejiang University), the United States (MIT, UCLA), Germany (Max Planck Institute), and South Korea (KAIST) continues to expand, the next decade is expected to witness accelerated innovation in DEAPA-enabled precision medicine.<\/p>\n","protected":false},"excerpt":{"rendered":"

        Development of pH-Responsive Drug Delivery Systems Using DEAPA 1. Introduction The advancement of targeted drug delivery systems has revolutionized modern pharmaceutical sciences, …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47],"tags":[],"class_list":["post-18284","post","type-post","status-publish","format-standard","hentry","category-zwml"],"_links":{"self":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts\/18284","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=18284"}],"version-history":[{"count":0,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts\/18284\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=18284"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=18284"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=18284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}