Carboxyl Groups Of PAA Research Articles

Construction of a Fluorescence/Phase-Change Dual-Mode Sensor Based on Carbon Dots/Poly(acrylic acid) for Highly Selective and Sensitive Detection of Ferric Ions.

Fe3+ is one of the crucial metal ions in biological systems, and its excess or deficiency in the body can trigger various diseases, posing a serious threat to human health. Moreover, improper handling or disposal of Fe3+ can lead to water pollution, thereby harming the environment. Therefore, the development of highly selective and sensitive Fe3+ detection probes is particularly urgent. In this paper, a dual-mode sensor based on sol-gel and fluorescence signal responses was developed for the visual detection of Fe3+. The visual sensing method based on the simultaneous response of Fe3+-triggered dual signals can minimize the interference from false-positive signals and enhance detection accuracy. The dual-mode sensor, denoted as PAA@CDs, was constructed by incorporating high-brightness (high fluorescence emission intensity) green-yellow carbon dots (CDs) into poly(acrylic acid) (PAA), which possesses a large number of carboxyl functional groups. Based on the interaction of Fe3+ with the surface functional groups of CDs, nonfluorescent complexes are formed, leading to nonradiative electron transfer, which induces fluorescence quenching and produces a fluorescence signal visible to the naked eye. Additionally, the interaction of Fe3+ with the carboxyl groups of PAA triggers the cross-linking of PAA, causing a sol-gel phase change signal. Consequently, the PAA@CDs exhibit a dual-response signal in Fe3+ detection. Based on the fluorescence method, the linear detection range of PAA@CDs for Fe3+ is 0.05-2.60 mM with a limit of detection (LOD) of 5.14 μM. Meanwhile, using the sol-gel method, the linear detection range is 0.02-2.20 mM, and the LOD is 42.5 μM. Furthermore, the PAA@CDs probes can be successfully applied to the detection of Fe3+ in real water samples, demonstrating their potential value in the analysis of real samples containing multiple ions.

Core-shell structured fiber as an iron ion self-reducible and self-anchorable Fenton catalyst for methylene blue high-efficient mineralization

The combination of GO decoration, PAA wet-spinning, Fe3+/Al3+ co-coordination with PANI coating was adopted to fabricate mechanically applicable core-shell structured fiber. Since GO could rely on its abundant oxygen-containing functional groups to interact with the carboxylic groups of PAA through hydrogen bonding and esterification crosslinking, GO decoration was expected to enhance the mechanical properties and water resistance of PAA matrix. Thanks to PANI-adjusted Fe3+/Fe2+ cycling, mass content of Fe2+ in PANI-coated fiber reached 0.08%, increasing by 242% compared to that of fibrous core. After the third cycle, Fe2+ mass content was 0.09% and higher than original content, and after 60 cycles, Fe2+ mass content was still as high as 0.09%; thus the resulting fiber could quickly catalyze H2O2 to mineralize 90% of MB during cyclic application. Due to strong PANI-induced iron ion-anchoring ability, iron ion leaching was only 0.36 mg/L during 60 cycles and less than 7% of that of fibrous core, so that the PANI-coated fiber could use its retained iron species to repeatedly decolorize MB at least 60 times. Since PANI shell could serve as an all-in-one locality to ensure Fe3+/Fe2+ cycling, pollutant mineralization, and iron ion anchoring, the fiber prepared herein presented its own superiority in treating dye wastewater.

A salt-free poly(acrylic acid) hydrogel electrolyte with self-released ions for quasi-solid-state electrochromic devices

The ionic conductivity of gel polymer electrolytes (GPEs) is usually provided by the added inorganic salt ions. Here, we report a salt-free poly(acrylic acid) (PAA) hydrogel electrolyte with an ionic conductivity of 3.7 × 10−3 S cm−1. The carboxylic groups of PAA can release free H+ ions to provide ionic conductivity, which not only simplifies the preparation of GPEs, but also benefits the fabrication of GPEs with high transparency (>95.6 % from 400 to 1000 nm). The as-prepared hydrogel electrolyte is assembled into an electrochromic (EC) device (ECD) by using Prussian blue/PAA GPE/hydrated tungsten trioxide. The fabricated ECD achieves a high optical modulation (72.7 %), fast responses (2.6 s for coloration and 2.2 s for bleaching), a high coloration efficiency (172.9 cm2 C−1) and good cycling stability (retaining 96.3 % of the original optical modulation after 1200 cycles). Moreover, the ECD has good energy storage properties, demonstrating a potential application for energy-storage smart windows.

Liquid Metal-Doped Conductive Hydrogel for Construction of Multifunctional Sensors.

Interest in wearable and stretchable multifunctional sensors has grown rapidly in recent years. The sensing elements must accurately detect external stimuli to expand their applicability as sensors. However, the sensor's self-healing and adhesion to a target object have been major challenges in developing such practical and versatile devices. In this study, we prepared a hydrogel (LM-SA-PAA) composed of liquid metal (LM), sodium alginate (SA), and poly(acrylic acid) (PAA) with ultrastretchable, excellent self-healing, self-adhesive, and high-sensitivity sensing capabilities that enable the conformal contact between the sensor and skin even during dynamic movements. The excellent self-healing performance of the hydrogel stems from its double cross-linked networks, including physical and chemical cross-linked networks. The physical cross-link formed by the ionic interaction between the carboxyl groups of PAA and gallium ions provide the hydrogel with reversible autonomous repair properties, whereas the covalent bond provides the hydrogel with a stable and strong chemical network. Alginate forms a microgel shell around LM nanoparticles via the coordination of its carboxyl groups with Ga ions. In addition to offering exceptional colloidal stability, the alginate shell has sufficient polar groups, ensuring that the hydrogel adheres to diverse substrates. Based on the efficient electrical pathway provided by the LM, the hydrogel exhibited strain sensitivity and enabled the detection of various human motions and electrocardiographic monitoring. The preparation method is simple and versatile and can be used for the low-cost fabrication of multifunctional sensors, which have broad application prospects in human-machine interface compatibility and medical monitoring.

A novel strategy for enhancing comprehensive properties of polyacrylate coating: Incorporation of highly dispersed zinc ions by using polyacrylic acid as carrier

The incorporation of metal ions into polyacrylate coating shows great potential in enhancing the performances of polyacrylate coatings, as well as providing additional functionalities. Herein, we developed a new type of water-soluble polyacrylic acid-Zn(II) composite (PAA-Zn) via the coordination of Zn2+ ions and carboxyl groups of PAA, which showed an extremely high stability in water in a wide range of pH (2–11). It was also facilely applied in polyacrylate latex (PL) as bifunctional additive to prepare high mechanical property, abrasion durable and antibacterial active coating. The PAA, acted as dispersing carrier of Zn2+ ions, and thus promoted uniform dispersion of Zn2+ ions in PL, while buffered the coordination between Zn2+ ions and PL. The as-prepared PL/PAA-Zn coating exhibited significantly improved tensile strength (11.45 MPa) and tear strength (21.01 kN/m) by 120% and 50% compared with those of pristine PL coating. Notably, abrasion durability was considerably enhanced in PL/PAA-Zn coating, showing the decreased mass loss by 36% when subjected to 2000 times of intensive abrasion with sandpaper (320 mesh) under 44 kPa. In addition, the PL/PAA-Zn coatings showed appreciable antibacterial activity against Gram-positive and Gram-negative bacteria. This work demonstrated a promising strategy for the uniform dispersion of metal ions in polyacrylate coatings for enhancing comprehensive properties.

Polyacrylonitrile/poly(acrylic acid) layer-by-layer superimposed composite nanofiber membrane with low iron ion leaching-out and stable methylene blue-removing performance

Membrane process is used to decontaminate dye wastewater. In the process of separation, the adsorbed and/or rejected dyes can greatly foul the membrane and negatively affect separation efficiency. Fenton oxidation can non-selectively mineralize dyes to prevent fouling the membrane. Therefore, this work focused on synthesizing the membrane coupled with Fenton catalyst for dye wastewater treatment. Polyacrylonitrile (PAN)/poly (acrylic acid) (PAA) composite nanofiber membrane was first prepared by layer-by-layer sequential electrospinning and then served as the substrate to load iron ions by the coordination of carboxyl groups of PAA with iron ions, after which a catalytic membrane was successfully prepared. During the application process, water would inevitably elute some iron ions from the catalytic membrane. In order to minimize the loss of iron ions, another PAA/PAN composite nanofiber membrane with the function of rejecting iron ions was then designed and superimposed onto the catalytic membrane using the adhesiveness of upper PAA layer. In this sense, the obtained composite membrane can stably catalyze H2O2 to effectively oxidize methylene blue (MB) due to low leaching-out of iron ions. The results showed that the iron ion loading ratio of PAN/PAA composite nanofiber membrane was increased by 167% compared to that of PAN nanofiber membrane, and the total iron ion elution ratios of PAN nanofiber membrane and PAN/PAA composite nanofiber membrane were 27 times and 6 times higher than that of superimposed composite membrane, respectively. As a result of high loading and low elution of iron ions, the superimposed composite membrane exhibited considerably stable efficiency for MB removal within 30 operation cycles, which reached up to 97.0%. Additionally, the superimposed composite membrane presented better mechanical property and more adjustable permeation flux than the control membranes, so that it would show a great potential for the application in the field of dye wastewater treatment.

Direct synthesis of substrate-independent nanoparticles for antibacterial application

In the present study, we designed a substrate-independent antimicrobial nanoparticle (SNP) via self-assembly of poly (acrylic acid) (PAA) and poly (diallyl dimethyl ammonium chloride) (PDDA). The prepared nanoparticle, with a cube structure, as revealed by scanning electron microscope (SEM), maintained structural integrity even after extensive washing. In addition, the SNP was endowed with substrate-independent adhesive affinity to various surfaces by carbodiimide reaction owing to the carboxyl group of PAA. The results of blood compatibility and cytocompatibility demonstrated that the SNP had a limited effect on blood coagulation and cell proliferation. The results of antibacterial tests indicated that the SNP exhibited significant inhibition ability for both gram-negative and gram-positive bacteria, reducing cell amount by 97.2% and 98.2% within 24 h for Escherichia coli and Staphylococcus aureus, respectively. The hemocompatibility and cytocompatibility were attributed to the introduction of carboxyl group, and the significantly antimicrobial property was ascribed to the introduction of PDDA. Furthermore, the SNP maintained outstanding long-term antimicrobial property. In general, it was believed that the designed SNP probably showed potential for applications in various biological and clinical fields.

Preparation and Characterization of Ionic Conductive Poly(acrylic Acid)-Based Silicone Hydrogels for Smart Drug Delivery System.

In this study, we developed a smart drug delivery system that can efficiently deliver the required amounts of drugs using the excellent ion conductivity of poly(acrylic acid) (PAA) and an electrical stimulus. As a result of its having carboxyl groups, PAA hydrogel can be used in drug delivery patches to release drugs by ionic conductivity. However, PAA hydrogel has low durability and poor mechanical properties. The carboxyl group of PAA was combined with a siloxane group of silicone using electron-beam irradiation to easily form a crosslinked structure. The PAA–silicone hydrogel has excellent mechanical properties. Specifically, the tensile strength increased more than 3.5 times. In addition, we observed its cell compatibility using fluorescence staining and CCK-8 assays and found good cell viability. Finally, it was possible to control the drug delivery rate efficiently using the voltage applied to the ion-conductive hydrogel. As the voltage was increased to 3, 5, and 7 V, the amount of drug released was 53, 88, and 96%, respectively. These excellent properties of the PAA–silicone hydrogel can be used not only for whitening or anti-wrinkling cosmetics but also in medical drug-delivery systems.

Water-Based Process to the Preparation of Nickel-Rich Li(Ni0.8Co0.1Mn0.1)O2 Cathode

Poly(acrylic acid) (PAA) is added as a binder to the water-based slurry of Ni-rich Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) powder. After adding PAA, the pH of the slurry changes from strongly alkaline to nearly neutral (pH9.0), making it suitable for casting on the aluminum current collector without corroding the aluminum (Al) and a largely increased adhesion from 318 to 458 kg m−2 after drying. The use of PAA also improves the dispersion of the slurry, because the carboxyl groups of PAA can interact with NCM811 to help stabilize the electrode particles in the slurry. Given the improved dispersion, reduced corrosion potential, and better adhesion, the resultant NCM811 cathode exhibits good structural integrity and greatly lowered charge-transfer resistance from 37.0 to 8.5 Ω, showing a high initial capacity of 189.2 mAh g−1 and capacity retention of 84.2% after 100 charge-discharge cycles under 0.2C.

Phosphorescent self-healing composites containing Re(I) complexes: preparation and properties

To obtain self-healing phosphorescent composites, four Re(I) complexes, Re-Ura-a (a = 1–4) with uracil group were synthesized. The ultraviolet-visible (UV-Vis) absorption spectra of Re-Ura-a (a = 1–4) are mainly comprised of the π→π* transitions (200–400 nm) and the metal-to-ligand charge transfer transitions (400–450 nm). The photoluminescence (PL) spectra of Re-Ura-a (a = 1–4) peaking at 576–584 nm possess the biexponential excited-state decay lifetimes (τ) of 0.19–0.43 μs. The PL spectra of Re-Ura-a@PAA (a = 1–4, PAA = polyacrylic acid) gel blocks redshift to ca. 600 nm with τ values of ca. 0.33 μs. The Re-Ura-1(0.6 wt%)@PAA gel blocks could bear maximum stress of 0.191 MPa and maximum strain of 525%, and they could be ca. 40% self-healed in 5 min after being severed. Finally, the energies of the H-bonds between the carboxylic group of PAA and different parts of Re-Ura-1 were theoretically simulated to investigate the intermolecular interactions between Re-Ura-1 and PAA.

Hydrophilic and Antibacterial Modification of Poly(lactic acid) Films by γ-ray Irradiation.

To improve the hydrophilicity and imparting antibacterial properties to poly(lactic acid), poly(acrylic acid) (PAA) and silver particles (AgNPs) were simultaneously introduced onto the surface of poly(lactic acid) (PLA) films by γ-ray irradiation. The morphology and structure of the modified films were characterized by scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) spectrometry and Fourier transform infrared (FTIR) spectroscopy. The interaction between PAA and AgNPs was investigated by X-ray photoelectron spectroscopy (XPS), confirming the coordination between AgNPs and the oxygen atom on the carboxylic group of PAA. The contact-angle (CA) measurements and antibacterial tests showed that the modified PLA films with a low silver content (PLA-g-PAA-Ag) exhibited excellent hydrophilicity as well as antibacterial activity compared with the neat PLA film.

High Performance Poly(methyl methacrylate-acrylic acid-divinylbenzene) Microcapsule Encapsulated Heat Storage Material for Thermoregulating Textiles

The preparation of high performance poly(methyl methacrylate-acrylic acid-divinylbenzene) (P(MMA-AADVB)) microcapsule encapsulating octadecane (OD) having carboxyl groups on the surface for textile application was studied. The P(MMA-methyl acrylate (MA)-DVB) microcapsule was previously prepared by microsuspension iodine transfer polymerization prior to hydrolysis of MA segment to obtain AA in the P(MMA-AA-DVB) shell. Using 30 wt% of MA and 20 wt% of DVB, the latent heats of melting and crystallization of the encapsulated OD were close to those of original OD (245 and 251 J/g-OD, respectively). After hydrolysis, the zeta potential value of the obtained P(MMA-AADVB) microcapsule surface was -33 mV representing the formation of carboxyl groups of PAA derived from PMA. The influences of nucleating agent amount and type on the reduction of supercooling were then investigated. Using 1-octadecanol at 10 wt% of OD provided the best result. Tc of the encapsulated OD increased and reached to that of original OD while the latent heats were maintained. The hydrolyzed P(MMA-AA-DVB) presented higher efficiency than P(MMA-MA-DVB) microcapsules for fabric coating without external binder which may due to the interaction of microcapsule surface functional group with fabric.

Facile fabrication of polyacrylic acid-polyvinyl chloride composite adsorbents for the treatment of cadmium-contaminated wastewater

Facile fabrication of polyacrylic acid-polyvinyl chloride (PAA-PVC) composite adsorbents and their evaluation for Cd(II) adsorption is reported in this study. The sorbents were prepared via a simple phase inversion process by spinning PAA-PVC polymer blends into mixed solution of water and methanol. The prepared fibers were characterized by scanning electron microscopy, energy disperse X-ray microscopy and Fourier transform infra-red microscopy, and their sorption performances were evaluated by batch sorption experiments. Through sorption isotherm, the maximum sorption capacity was estimated as 331.59 mg/g using the Langmuir isotherm model. Intra-particle diffusion played a major role in reaching the adsorption equilibrium. Ion-exchange between the charged carboxyl groups of PAA and the Cd(II) solution was observed to be the main mechanism of Cd(II) sorption. This study is believed to pave way for preparing cost-effective polymeric composite sorbents for the removal of heavy metals from polluted waters.

PH-responsive drug release and real-time fluorescence detection of porous silica nanoparticles

In this work, pH-sensitive “dual-switch” porous silica (pSiO2) nanoparticles (NPs) were constructed for drug delivery. Poly(acrylic acid) (PAA) was grafting onto the internal and external surfaces of amino groups functionalized porous silica (pSiO2-NH2) NPs by the amidation between the amino groups and the carboxyl groups of PAA for pH triggered drug release. The resultant pSiO2/PAA NPs have an average diameter of 50–60nm and high specific surface area (914m2·g−1). To improve the loading capacity, ZnO quantum dots (QDs) were used to block the partial pores of pSiO2/PAA and the loading capacity reached to 28% for methotrexate (MTX) model drug. The in vitro cellular cytotoxicity test and a hemolysis assay demonstrated that the pSiO2/PAA/ZnO NPs were highly biocompatible and suitable to utilize as drug carriers. The MTX-loaded pSiO2/PAA/ZnO NPs displayed more efficient cytotoxic to HepG2 cells than free MTX. The pSiO2/PAA/ZnO NPs displayed low premature, pH-responsive release and pH-dependent fluorescence. Moreover, pH-dependent fluorescence enables to trace MTX release behavior.

Temperature-, pH- and CO₂-Sensitive Poly(N-isopropylacryl amide-co-acrylic acid) Copolymers with High Glass Transition Temperatures.

A series of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAAm-co-PAA) random copolymers were synthesized through free radical copolymerization in MeOH. The incorporation of the acrylic acid units into PNIPAAm tended to enhance the glass transition temperature (Tg), due to strong intermolecular hydrogen bonding between the amide groups of PNIPAAm and the carboxyl groups of PAA, as observed using 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopic analyses. The lower critical solution temperature (LCST) increased upon increasing the pH of the aqueous solution containing PNIPAAm-co-PAA because the COOH groups of the PAA segment dissociated into COO− groups, enhancing the solubility of the copolymer. In addition, high-pressure differential scanning calorimetry revealed that the LCSTs of all the aqueous solutions of the copolymers decreased upon increasing the pressure of CO2, suggesting that CO2 molecules had displaced H2O molecules around the polar CONH and COOH groups in PNIPAAm-co-PAA, thereby promoting the hydrophobicity of the copolymers in the aqueous solution. In addition, the values of Tg of a film sample increased upon treatment with supercritical CO2, implying that intermolecular interactions in the copolymer had been enhanced after such treatment.

Adsorption of poly(acrylic acid) on the surface of microporous activated carbon obtained from cherry stones

The adsorption properties of microporous activated carbon (CSDA) obtained by direct activation of cherry stones in relation to low-molecular weight poly(acrylic acid) − PAA were examined. The solution pH influence and molecular weight of the polymer were examined. The PAA adsorbed amounts were correlated with the solid surface charge density and zeta potential of the solid particle in the polymer presence. The obtained results indicated that the highest adsorption on the activated carbon surface is exhibited by PAA with lower molecular weight at pH 3 (it reaches the level of 25mg/g). Thus, under such conditions the CSDA is the most efficient adsorbent for poly(acrylic acid) removal from aqueous solution. The polymeric adsorption layer at pH 3 is composed of more coiled macromolecules (low degree of PAA carboxyl groups dissociation) which are electrostatically attracted to the positively charged solid surface. It was also proved that applied low-cost activated carbon can be used for removal of undesirable low-molecular polymers from wastewaters.

The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications

The use of polymers as biomaterials has provided significant advantages in therapeutic applications. In particular, the possibility to modify and functionalize polymer chains with compounds that are able to improve biocompatibility, mechanical properties, or cell viability allows the design of novel materials to meet new challenges in the biomedical field. With the polymer functionalization strategies, click chemistry is a powerful tool to improve cell-compatibility and drug delivery properties of polymeric devices. Similarly, the fundamental need of biomedicine to use sterile tools to avoid potential adverse-side effects, such as toxicity or contamination of the biological environment, gives rise to increasing interest in the microwave-assisted strategy. The combination of click chemistry and the microwave-assisted method is suitable to produce biocompatible hydrogels with desired functionalities and improved performances in biomedical applications. This work aims to synthesize RGD-functionalized hydrogels. RGD (arginylglycylaspartic acid) is a tripeptide that can mimic cell adhesion proteins and bind to cell-surface receptors, creating a hospitable microenvironment for cells within the 3D polymeric network of the hydrogels. RGD functionalization occurs through Huisgen 1,3-dipolar cycloaddition. Some PAA carboxyl groups are modified with an alkyne moiety, whereas RGD is functionalized with azido acid as the terminal residue of the peptide sequence. Finally, both products are used in a copper catalyzed click reaction to permanently link the peptide to PAA. This modified polymer is used with carbomer, agarose and polyethylene glycol (PEG) to synthesize a hydrogel matrix. The 3D structure is formed due to an esterification reaction involving carboxyl groups from PAA and carbomer and hydroxyl groups from agarose and PEG through microwave-assisted polycondensation. The efficiency of the gelation mechanism ensures a high degree of RGD functionalization. In addition, the procedure to load therapeutic compounds or biological tools within this functionalized network is very simple and reproducible.

Loading of Antibiotics into Polyelectrolyte Multilayers after Self-Assembly and Tunable Release by Catechol Reaction

The colonization of bacteria on biomedical implants and subsequent forming of biofilm often leads to serious infections. In this work, poly(acrylic acid) modified by dopamine (PAA-dopa) and poly(ethylenimine) (PEI) self-assembled into multilayer films were used to load and for sustained release of antibiotics. The obtained multilayer films were immersed in tris-buffered saline containing gentamicin sulfate (GS) to load the antibiotics and were cross-linked via catechol chemistry of dopa. Through raising pH value, more carboxyl groups of PAA were protonated and combined with GS through electrostatic forces. After cross-linking, the multilayer films were used as a drug delivery system to embed GS in the matrices which showed a two-stage sustained release profile. In vitro, the release of GS into phosphate-buffered saline (PBS) from the multilayer films, as well as the antibacterial activity, was determined. The drug-loaded multilayer films showed excellent bactericidal function against Staphylococcus aureus...

Synthesis of magnetite nanoparticles coated with poly(acrylic acid) by photopolymerization

Magnetite nanoparticles were coated with poly(acrylic acid) layer by a simple and efficient method of photopolymerization. Structure and morphology of prepared nanoparticles were characterized by ATR-FT IR, XRD and TEM analysis. Moreover, thermal stability and content of magnetite in nanoparticles has been determined by thermogravimetry (TGA). It was found that resulting nanoparticles were covered by a thin, durable shell of crosslinked PAA (thus, insoluble in water). Nanoparticles were characterized by a very small size (in range of 6–13nm) and high content of the magnetite (81%). The protective coating on the magnetite surface is a result of interactions between carboxyl groups of PAA and Fe3O4 particles.

Patterned Poly(acrylic acid) Brushes Containing Gold Nanoparticles for Peptide Detection by Surface-Assisted Laser Desorption/Ionization Mass Spectrometry.

Patterned poly(acrylic acid) (PAA) brushes was successfully generated via photolithography and surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylic acid as verified by water contact angle measurements and FT-IR analysis. The carboxyl groups of PAA brushes can act as reducing moieties for in situ synthesis of gold nanoparticles (AuNPs), without the use of additional reducing agent. The formation of AuNPs was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. The glass surface-modified by PAA brushes and immobilized with AuNPs (AuNPs-PAA) can be used as a substrate for SALDI-MS analysis, which is capable of detecting both small peptides having m/z ≤ 600 (glutathione) and large peptides having m/z ≥ 1000 (bradykinin, ICNKQDCPILE) without the interference from matrix signal suggesting that AuNPs were stably trapped within the PAA brushes and the carboxyl groups of PAA can serve as internal proton source. By employing AuNPs as the capture probe, the AuNPs-PAA substrate can selectively identify thiol-containing peptides from the peptide mixtures with LOD as low as 0.1 and 0.05 nM for glutathione and ICNKQDCPILE, respectively. An ability to selectively detect ICNKQDCPILE in a diluted human serum is also demonstrated. The patterned format together with its high sensitivity and selectivity render this newly developed substrate a potential platform for high-throughput analysis of other biomarkers, especially those with low molecular weight in complex biological samples.