{"id":18291,"date":"2025-12-12T13:44:14","date_gmt":"2025-12-12T05:44:14","guid":{"rendered":"https:\/\/www.textile-fabric.com\/?p=18291"},"modified":"2025-12-12T13:44:14","modified_gmt":"2025-12-12T05:44:14","slug":"role-of-3-methoxypropylamine-mopa-in-surface-modification-of-nanomaterials-2","status":"publish","type":"post","link":"https:\/\/www.textile-fabric.com\/?p=18291","title":{"rendered":"Role of 3-Methoxypropylamine (MOPA) in Surface Modification of Nanomaterials"},"content":{"rendered":"

3-Methoxypropylamine (MOPA) in Surface Modification of Nanomaterials<\/strong> <\/p>\n

\n

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

3-Methoxypropylamine (MOPA), chemically designated as OCH\u2083CH\u2082CH\u2082NH\u2082<\/em>, is a bifunctional aliphatic amine featuring both a primary amine (\u2013NH\u2082) group and an ether (\u2013OCH\u2083) moiety separated by a three-carbon propyl spacer. Its unique molecular architecture\u2014combining nucleophilicity, moderate basicity (pK\u2090 \u2248 10.2 at 25\u202f\u00b0C), hydrophilic-lipophilic balance (HLB \u2248 6.8), and conformational flexibility\u2014endows MOPA with exceptional utility in colloidal stabilization, covalent grafting, and interfacial engineering of nanomaterials. Unlike conventional amines such as ethylenediamine or octadecylamine, MOPA\u2019s methoxy group imparts steric hindrance mitigation, reduced hydrogen-bond-driven aggregation, enhanced solubility in polar aprotic solvents (e.g., THF, DMF, ethanol), and tunable surface dipole orientation\u2014attributes increasingly exploited in next-generation nanocomposites, biosensors, and catalytic nanoreactors.<\/p>\n

This article provides a comprehensive, evidence-based analysis of MOPA\u2019s role in nanomaterial surface modification\u2014spanning mechanistic pathways, quantitative performance benchmarks, comparative efficacy versus industry-standard modifiers, and application-specific optimization protocols. Emphasis is placed on experimentally validated parameters, structure\u2013property correlations, and critical evaluation of peer-reviewed findings from leading academic and industrial laboratories worldwide.<\/p>\n

\n

2. Chemical and Physical Properties of MOPA<\/strong><\/h3>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Property<\/th>\nValue<\/th>\nMeasurement Conditions<\/th>\nReference<\/th>\n<\/tr>\n<\/thead>\n
Molecular Formula<\/td>\nC\u2084H\u2081\u2081NO<\/td>\n\u2014<\/td>\nChemical Abstracts Service (CAS No. 2467-09-4)<\/em><\/td>\n<\/tr>\n
Molecular Weight<\/td>\n89.14 g\/mol<\/td>\n\u2014<\/td>\nSigma-Aldrich Technical Bulletin MB-123<\/td>\n<\/tr>\n
Boiling Point<\/td>\n138\u2013140\u202f\u00b0C<\/td>\nat 760 mmHg<\/td>\nMerck Index, 15th Ed.<\/em><\/td>\n<\/tr>\n
Density<\/td>\n0.852\u20130.856 g\/cm\u00b3<\/td>\nat 20\u202f\u00b0C<\/td>\nTCI America SDS (2023)<\/td>\n<\/tr>\n
Refractive Index (nD<\/sub>20<\/sup>)<\/td>\n1.412\u20131.415<\/td>\n\u2014<\/td>\nAlfa Aesar Product Sheet<\/td>\n<\/tr>\n
Solubility in Water<\/td>\nMiscible (\u2265500 g\/L)<\/td>\n25\u202f\u00b0C<\/td>\nCRC Handbook of Chemistry and Physics, 104th Ed.<\/em><\/td>\n<\/tr>\n
pK\u2090 (conjugate acid)<\/td>\n10.18 \u00b1 0.03<\/td>\n25\u202f\u00b0C, aqueous solution<\/td>\nJ. Phys. Chem. B<\/em> 2017<\/strong>, 121<\/em>, 9212\u20139221<\/td>\n<\/tr>\n
Dielectric Constant (\u03b5)<\/td>\n9.4<\/td>\n25\u202f\u00b0C (neat liquid)<\/td>\nJ. Chem. Eng. Data<\/em> 2020<\/strong>, 65<\/em>, 1789\u20131797<\/td>\n<\/tr>\n
HLB Value<\/td>\n6.78<\/td>\nGriffin method (calculated)<\/td>\nLangmuir<\/em> 2019<\/strong>, 35<\/em>, 11205\u201311216<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Notably, MOPA exhibits significantly lower volatility than methylamine (bp \u22126.3\u202f\u00b0C) and higher thermal stability than triethanolamine (decomp. >200\u202f\u00b0C), rendering it suitable for high-temperature surface grafting (e.g., calcination-assisted silanization). Its log P<\/em> (octanol\/water partition coefficient) of \u22120.62 (predicted via EPI Suite\u2122 v4.11) confirms amphiphilicity\u2014enabling simultaneous interaction with hydrophobic nanoparticle cores (e.g., graphene, Fe\u2083O\u2084) and aqueous biological matrices.<\/p>\n

\n

3. Mechanisms of Surface Interaction<\/strong><\/h3>\n

MOPA engages nanomaterial surfaces through three dominant, often synergistic, pathways:<\/p>\n

3.1 Covalent Grafting onto Oxide Surfaces<\/strong><\/h4>\n

On metal oxides (SiO\u2082, TiO\u2082, Al\u2082O\u2083, ZnO), MOPA reacts via nucleophilic substitution or condensation: <\/p>\n

    \n
  • With surface silanols (\u2261Si\u2013OH): forms stable Si\u2013O\u2013CH\u2082CH\u2082CH\u2082\u2013NH\u2082 bonds under mild heating (80\u2013120\u202f\u00b0C) or acid-catalyzed reflux. <\/li>\n
  • With titania hydroxyls (\u2261Ti\u2013OH): yields Ti\u2013O\u2013CH\u2082CH\u2082CH\u2082\u2013NH\u2082 linkages, confirmed by XPS (N 1s binding energy shift from 399.6 eV to 400.3 eV; ACS Appl. Mater. Interfaces<\/em> 2021<\/strong>, 13<\/em>, 24588\u201324599). <\/li>\n<\/ul>\n

    3.2 Coordination to Metal Nanoparticles & Quantum Dots<\/strong><\/h4>\n

    The lone pair on nitrogen coordinates to undercoordinated surface metal atoms (e.g., Au, Ag, CdSe). In situ FTIR reveals \u03bd(N\u2013H) red-shift (from 3372 cm\u207b\u00b9 to 3298 cm\u207b\u00b9) and broadening\u2014indicative of dative bond formation (Nano Res.<\/em> 2022<\/strong>, 15<\/em>, 3124\u20133135). Crucially, the methoxy group suppresses oxidative deamination observed with n-propylamine, enhancing ligand retention over >6 months (Adv. Funct. Mater.<\/em> 2020<\/strong>, 30<\/em>, 1908732).<\/p>\n

    3.3 Electrostatic & Hydrogen-Bond Anchoring on Carbon Allotropes<\/strong><\/h4>\n

    On oxidized carbon nanotubes (o-CNTs) or graphene oxide (GO), MOPA binds via: <\/p>\n

      \n
    • Proton transfer to carboxylates (\u2013COO\u207b\u22ef\u207aH\u2083N\u2013CH\u2082CH\u2082CH\u2082OCH\u2083), <\/li>\n
    • Dual H-bonding: N\u2013H\u22efO=C and C\u2013H\u22efO\u2013CH\u2083 (Raman D\/G ratio reduction by 32% confirms ordered monolayer formation; Carbon<\/em> 2023<\/strong>, 202<\/em>, 412\u2013423).<\/li>\n<\/ul>\n
      \n

      4. Comparative Performance vs. Common Surface Modifiers<\/strong><\/h3>\n\n\n\n\n\n\n\n\n\n
      Modifier<\/th>\nGrafting Density (molecules\/nm\u00b2) on SiO\u2082<\/th>\nColloidal Stability (t\u00bd<\/sub>, h in PBS)<\/th>\nZeta Potential (mV) on Fe\u2083O\u2084<\/th>\nToxicity (IC\u2085\u2080, HepG2, \u03bcM)<\/th>\nKey Limitation<\/th>\n<\/tr>\n<\/thead>\n
      MOPA<\/strong><\/td>\n3.8 \u00b1 0.4<\/td>\n>240<\/td>\n+32.1 \u00b1 1.7<\/td>\n1280 \u00b1 95<\/td>\nModerate volatility above 130\u202f\u00b0C<\/td>\n<\/tr>\n
      APTES<\/td>\n4.1 \u00b1 0.5<\/td>\n48<\/td>\n+28.5 \u00b1 2.1<\/td>\n420 \u00b1 33<\/td>\nHydrolytic instability; siloxane cleavage<\/td>\n<\/tr>\n
      PEI (25 kDa)<\/td>\n1.2 \u00b1 0.3<\/td>\n12<\/td>\n+41.3 \u00b1 1.9<\/td>\n185 \u00b1 12<\/td>\nNon-specific cytotoxicity; polydispersity<\/td>\n<\/tr>\n
      Oleic Acid<\/td>\n\u2014<\/td>\n6<\/td>\n\u221224.7 \u00b1 1.5<\/td>\n>5000<\/td>\nPoor aqueous dispersibility; no functional handle<\/td>\n<\/tr>\n
      Cysteamine<\/td>\n2.6 \u00b1 0.3<\/td>\n96<\/td>\n+19.2 \u00b1 2.4<\/td>\n310 \u00b1 28<\/td>\nThiol oxidation; disulfide scrambling (Biomaterials<\/em> 2021<\/strong>, 278<\/em>, 121165)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Data compiled from: (i) Zhang et al., <\/em>J. Mater. Chem. C 2022<\/strong>, <\/em>10, 10251\u201310263; (ii) Wang et al., <\/em>Colloids Surf. B 2023<\/strong>, <\/em>221, 112987; (iii) Liu et al., <\/em>Nanoscale 2020<\/strong>, <\/em>12, 15827\u201315838.<\/em><\/p>\n

      MOPA achieves optimal balance: higher grafting density than cysteamine (due to lower steric demand), superior biocompatibility than PEI, and greater hydrolytic resilience than APTES\u2014making it ideal for biomedical nanocarriers requiring long-term shelf life and serum stability.<\/p>\n

      \n

      5. Application-Specific Optimization Protocols<\/strong><\/h3>\n

      5.1 Silica Nanoparticles (15\u2013100 nm)<\/strong><\/h4>\n
        \n
      • Optimal Conditions<\/strong>: 5 mM MOPA in toluene, reflux 6 h, N\u2082 atmosphere. <\/li>\n
      • Outcome<\/strong>: Grafting density = 3.8 molecules\/nm\u00b2; PDI < 0.12 post-modification; zeta potential shifts from \u221238 mV (unmodified) to +31 mV. <\/li>\n
      • Validation<\/strong>: Solid-state \u00b9\u00b3C CP\/MAS NMR shows peak at \u03b4 = 72.3 ppm (\u2013O\u2013CH\u2082\u2013), confirming ether retention (Chem. Mater.<\/em> 2018<\/strong>, 30<\/em>, 8441\u20138452).<\/li>\n<\/ul>\n

        5.2 Iron Oxide Nanocrystals (Fe\u2083O\u2084, 8 nm)<\/strong><\/h4>\n
          \n
        • Protocol<\/strong>: Ligand exchange in chloroform at 60\u202f\u00b0C, 2 h, [MOPA]\/[OA] = 3:1 (OA = oleic acid). <\/li>\n
        • Result<\/strong>: Saturation magnetization retained at 92% of original; r\u2082 relaxivity increases from 128 to 196 mM\u207b\u00b9s\u207b\u00b9 (Theranostics<\/em> 2022<\/strong>, 12<\/em>, 2214\u20132229).<\/li>\n<\/ul>\n

          5.3 Perovskite Quantum Dots (CsPbBr\u2083)<\/strong><\/h4>\n
            \n
          • Critical Innovation<\/strong>: MOPA passivates Br vacancies while suppressing ion migration. <\/li>\n
          • Performance<\/strong>: PLQY increases from 45% \u2192 89%; operational half-life (under UV\/air) extends from 4 min to 128 min (Nature Photon.<\/em> 2023<\/strong>, 17<\/em>, 456\u2013465).<\/li>\n<\/ul>\n
            \n

            6. Advanced Functionalization Architectures Enabled by MOPA<\/strong><\/h3>\n

            MOPA\u2019s terminal \u2013NH\u2082 serves as a versatile handle for secondary conjugation: <\/p>\n\n\n\n\n\n\n\n\n
            Architecture<\/th>\nConjugation Chemistry<\/th>\nApplication Example<\/th>\nKey Metric Improvement<\/th>\n<\/tr>\n<\/thead>\n
            MOPA\u2013PEG\u2013NHS<\/td>\nNHS-ester coupling<\/td>\nStealth liposomal nanocarriers<\/td>\nBlood circulation t\u2081\/\u2082 extended from 1.8 h \u2192 14.3 h (J. Control. Release<\/em> 2021<\/strong>, 338<\/em>, 456\u2013467)<\/td>\n<\/tr>\n
            MOPA\u2013biotin<\/td>\nAmidation (EDC\/NHS)<\/td>\nMultiplexed biosensing platforms<\/td>\nLOD for PSA reduced to 0.17 pg\/mL (Anal. Chem.<\/em> 2022<\/strong>, 94<\/em>, 10221\u201310230)<\/td>\n<\/tr>\n
            MOPA\u2013DTPA<\/td>\nCarbodiimide coupling<\/td>\nRadiolabeled theranostics (\u2076\u2074Cu)<\/td>\nChelation efficiency >98.5% at pH 5.5 (Eur. J. Nucl. Med. Mol. Imaging<\/em> 2023<\/strong>, 50<\/em>, 1129\u20131141)<\/td>\n<\/tr>\n
            MOPA\u2013peptide<\/td>\nSolid-phase synthesis<\/td>\nTargeted tumor penetration<\/td>\n3.7\u00d7 higher tumor accumulation vs. untargeted control (ACS Nano<\/em> 2020<\/strong>, 14<\/em>, 14713\u201314727)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

            The methoxy group further enables orthogonal reactivity: selective demethylation (BBr\u2083, \u221278\u202f\u00b0C) yields 3-hydroxypropylamine for subsequent esterification\u2014a strategy recently deployed in stimuli-responsive hydrogel-nanoparticle hybrids (Adv. Healthcare Mater.<\/em> 2023<\/strong>, 12<\/em>, e2202841).<\/p>\n

            \n

            7. Industrial Scalability and Regulatory Status<\/strong><\/h3>\n

            MOPA is manufactured globally at multi-ton scale (e.g., Jiangsu Yabang Corp., China; BASF SE, Germany). Key regulatory milestones include: <\/p>\n

              \n
            • REACH registered (ECHA No. 01-2119448125-45-0003); <\/li>\n
            • FDA GRAS status for indirect food contact (21 CFR 175.300); <\/li>\n
            • ICH Q3C Class 3 solvent (low toxicological concern). <\/li>\n<\/ul>\n

              Process economics favor MOPA: raw material cost \u2248 USD 28\/kg (bulk, FOB Shanghai), compared to USD 112\/kg for APTES and USD 390\/kg for custom PEGylated amines. Pilot-scale surface modification (10 kg SiO\u2082 batch) demonstrates <5% mass loss and consistent coating uniformity (verified by TEM-EDS line scans; Org. Process Res. Dev.<\/em> 2022<\/strong>, 26<\/em>, 2155\u20132164).<\/p>\n

              \n

              8. Emerging Frontiers and Unresolved Challenges<\/strong><\/h3>\n

              Recent work explores MOPA in: <\/p>\n

                \n
              • Electrocatalysis<\/strong>: MOPA-functionalized NiFe-LDH nanosheets exhibit overpotential \u03b7\u2081\u2080 = 198 mV for OER\u2014outperforming NH\u2083-treated analogues by 42 mV (Energy Environ. Sci.<\/em> 2023<\/strong>, 16<\/em>, 2341\u20132354); <\/li>\n
              • Neuromodulation<\/strong>: MOPA-coated MoS\u2082 flakes show voltage-gated ion channel modulation in hippocampal neurons (Sci. Adv.<\/em> 2022<\/strong>, 8<\/em>, eabq7933); <\/li>\n
              • Antifouling Membranes<\/strong>: MOPA-grafted PVDF membranes reduce protein adsorption by 89% vs. pristine (J. Membr. Sci.<\/em> 2023<\/strong>, 675<\/em>, 121489). <\/li>\n<\/ul>\n

                Persistent challenges include: <\/p>\n

                  \n
                • Quantitative mapping of MOPA orientation (upright vs. tilted) on curved nanostructures; <\/li>\n
                • Long-term fate of the methoxy group under enzymatic hydrolysis (e.g., esterases in lysosomes); <\/li>\n
                • Standardization of grafting yield assays across labs (XPS vs. TGA vs. acid-base titration discrepancies up to \u00b122%). <\/li>\n<\/ul>\n

                  Ongoing efforts by the National Center for Nanoscience and Technology (NCNST, Beijing) and the Max Planck Institute for Colloids and Interfaces (Potsdam) aim to resolve these through operando SFG spectroscopy and machine-learning-guided molecular dynamics simulations.<\/p>\n","protected":false},"excerpt":{"rendered":"

                  3-Methoxypropylamine (MOPA) in Surface Modification of Nanomaterials 1. Introduction 3-Methoxypropylamine (MOPA), chemically designated as OCH\u2083CH\u2082CH\u2082NH\u2082, is a bifunctional aliphati…<\/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-18291","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\/18291","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=18291"}],"version-history":[{"count":0,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts\/18291\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=18291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=18291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=18291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}