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Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.

Silicon, serving as an anode material of Li‐ion batteries, offers a theoretical capacity significantly higher than graphite, but its practical application is hindered by poor conductivity, low lithium ion diffusivity, and severe volumetric expansion. Here, a simple and eco‐friendly methodology is proposed to synthesize precisely prelithiated polyacrylic acid binder, optimizing the interface between the binder and micron Si particles. The incorporation of these binders not only mitigates the detrimental effects of volumetric expansion but also enhances mechanical strength, and ionic conductivity of the anode, significantly improving the initial Coulombic efficiency (ICE), cycling stability, and rate performance of micron‐sized Si anodes. This study not only highlights the potential of prelithiated binders in overcoming the limitations of micron‐sized Si anodes but also sets a new benchmark for the development of high‐capacity, eco‐friendly Li‐ion batteries. Precisely prelithiation not only enhances the mechanical properties of PAA binders but also provides extra Li for electrode to form a stable SEI layer, thus improving electrochemical performance of micron‐sized silicon anodes for lithium‐ion batteries. Among those prelithiated PAAs (LiPAAs), LiPAA‐3 exhibits the best adhesion and strength, leading to a remarkable reversible capacity and an excellent ICE of Si−LiPAA‐3 electrode.

In this study, polyacrylic acid hydrogels were prepared by modulating the cross-linking agent mass ratio using UV and heat curing methods. The structures and properties of the hydrogels were characterized and analyzed using Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The results showed that the mechanical properties of the hydrogels prepared through UV curing were better than those prepared through heat curing. The maximum mechanical tensile strength of 139 kPa was achieved at a cross-linking agent mass ratio of 3.85% with 20 min of UV curing, and the maximum mechanical compressive strength of 0.16 MPa was achieved at a cross-linking agent mass ratio of 2.91% with 20 min of UV curing. However, the hydrogels prepared by heat curing had a higher tensile strength than those prepared using the heat curing method. In addition, the thermally cured hydrogels had higher water absorption and adsorption properties. Moreover, the PAA hydrogels prepared at cross-linking agent mass ratios of 1.91 and 2.91% with 2 h of the heat curing method had the best swelling properties. Moreover, the increase in the cross-linker mass concentration led to a decrease in the pore size and porosity and to a more compact structure.

Highly monodispersed and colloidal magnetite nanoparticles (MNPs) with controlled particle sizes and biocompatible polymer coatings have recently revealed a good ability for magnetic fluid hyperthermia (MFH) applications. Herein, we focused on probing the thermal abilities of polyacrylic acid (PAA)-decorated MNPs (PMNPs) under alternating magnetic field (AMF) with different frequencies and field amplitudes. The as-prepared PMNPs were fully characterized using various techniques including TEM, FTIR, DLS, TGA, and VSM. The results illustrated uniform colloidal well-dispersed ultra-small MNPs (core = 5 nm) with hydrodynamic sizes of (D H  = 60 nm) and superparamagnetic behaviour. PAA-MNPs in water showed a good self-heating efficiencies, particularly when minimal concentration of MNPs (2.5 mg/mL) were employed. Heating profiles depicted that hyperthermia temperatures (42 °C) can be reached in relatively short times and could rise up to 53 °C. Heating abilities and SAR values as functions of frequency, field amplitude of AMF and concentration were systematically investigated. A remarkable increase of SAR with decreasing concentration and increasing frequency as well as amplitude was found. For instance, SAR was found to be 36 W/g and 6.75 for concentration of 2.5 and 10 mg/ml, respectively. Thus, it was concluded that by altering main MFH parameters, the heat can be effectively tuned for possible use in magnetic hyperthermia.

Background: We conducted intratracheal instillations of different molecular weights of polyacrylic acid (PAA) into rats in order to examine what kinds of physicochemical characteristics of acrylic acid-based polymer affect responses in the lung. Methods: F344 rats were intratracheally exposed to a high molecular weight (HMW) of 598 thousand g/mol or a low molecular weight (LMW) of 30.9 thousand g/mol PAA at low and high doses. Rats were sacrificed at 3 days, 1 week, 1 month, 3 months and 6 months post exposure. Results: HMW PAA caused persistent increases in neutrophil influx, cytokine-induced neutrophil chemoattractants (CINC) in the bronchoalveolar lavage fluid (BALF), and heme oxygenase-1 (HO-1) in the lung tissue from 3 days to 3 months and 6 months following instillation. On the other hand, LMW PAA caused only transient increases in neutrophil influx, CINC in BALF, and HO-1 in the lung tissue from 3 days to up to 1 week or 1 month following instillation. Histopathological findings of the lungs demonstrated that the extensive inflammation and fibrotic changes caused by the HMW PAA was greater than that in exposure to the LMW PAA during the observation period. Conclusion: HMW PAA induced persistence of lung disorder, suggesting that molecular weight is a physicochemical characteristic of PAA-induced lung disorder.

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln2O3) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T2) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r2 values were appreciable at a 3.0 T MR field and higher at a 9.4 T MR field, whereas their r1 values were negligible at all MR fields, indicating their exclusive induction of T2 relaxations with negligible induction of T1 relaxations. Their effectiveness as T2 MRI contrast agents at high MR fields was confirmed from strong negative contrast enhancements in in vivo T2 MR images at a 9.4 T MR field after intravenous administration into mice tails.

We conducted intratracheal instillations of polyacrylic acid (PAA) with crosslinking and non-crosslinking into rats in order to examine what kinds of physicochemical characteristics of acrylic-acid-based polymers affect responses in the lung. F344 rats were intratracheally exposed to similar molecular weights of crosslinked PAA (CL-PAA) (degree of crosslinking: ~0.1%) and non-crosslinked PAA (Non-CL-PAA) at low and high doses. Rats were sacrificed at 3 days, 1 week, 1 month, 3 months, and 6 months post-exposure. Both PAAs caused increases in neutrophil influx, cytokine-induced neutrophil chemoattractants (CINC) in the bronchoalveolar lavage fluid (BALF), and heme oxygenase-1 (HO-1) in the lung tissue from 3 days to 6 months following instillation. The release of lactate dehydrogenase (LDH) activity in the BALF was higher in the CL-PAA-exposed groups. Histopathological findings of the lungs demonstrated that the extensive fibrotic changes caused by CL-PAA were also greater than those in exposure to the Non-CL- PAA during the observation period. CL-PAA has more fibrogenicity of the lung, suggesting that crosslinking may be one of the physicochemical characteristic factors of PAA-induced lung disorder.

Background Some organic chemicals are known to cause allergic disorders such as bronchial asthma and hypersensitivity pneumonitis, and it has been considered that they do not cause irreversible pulmonary fibrosis. It has recently been reported, however, that cross-linked acrylic acid-based polymer, an organic chemical, might cause serious interstitial lung diseases, including pulmonary fibrosis. We investigated whether or not intratracheal instillation exposure to cross-linked polyacrylic acid (CL-PAA) can cause lung disorder in rats. Methods Male F344 rats were intratracheally instilled with dispersed CL-PAA at low (0.2 mg/rat) and high (1.0 mg/rat) doses, and were sacrificed at 3 days, 1 week, 1 month, 3 months and 6 months after exposure to examine inflammatory and fibrotic responses and related gene expressions in the lungs. Rat lungs exposed to crystalline silica, asbestos (chrysotile), and NiO and CeO 2 nanoparticles were used as comparators. Results Persistent increases in total cell count, neutrophil count and neutrophil percentage, and in the concentration of the cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2 and C-X-C motif chemokine 5 (CXCL5), which correlated with lung tissue gene expression, were observed in bronchoalveolar lavage fluid (BALF) from 3 days until at least 1 month following CL-PAA intratracheal instillation. Persistent increases in heme oxygenase-1 (HO-1) in the lung tissue were also observed from 3 days to 6 months after exposure. Histopathological findings of the lungs demonstrated that extensive inflammation at 3 days was greater than that in exposure to silica, NiO nanoparticles and CeO 2 nanoparticles, and equal to or greater than that in asbestos (chrysotile) exposure, and the inflammation continued until 1 month. Fibrotic changes also progressed after 1 month postexposure. Conclusion Our results suggested that CL-PAA potentially causes strong neutrophil inflammation in the rat and human lung.

This study evaluated a biomimetic filler strategy for two-step universal dental adhesives by integrating amine-functionalized mesoporous silica nanoparticles (MSNs) loaded with polyacrylic acid-stabilized amorphous calcium phosphate (PA–ACP) into the primer phase. MSNs were synthesized and characterized by FTIR, N2 sorption (BET), and HRTEM to confirm structural integrity and effective PA–ACP loading. Two commercial adhesives (G2 Bond and OptiBond eXTRa) were modified by incorporating different volumes fractions (10, 15, 20 vol%) of PA–ACP/MSN. Wettability (contact angle), microtensile bond strength (μTBS), and cytotoxicity (indirect MTT assay using human periodontal ligament fibroblasts, HPLFs) were assessed. The results demonstrated that incorporating up to 15 vol% PA–ACP/MSN maintained favorable wettability and bond strength, comparable to those of the unmodified controls. At 20 vol%, significant increases in contact angles and reductions in bond strength indicated impaired primer infiltration. Cytotoxicity testing confirmed high fibroblast viability (>70%) across all tested concentrations, verifying the biocompatibility of PA–ACP/MSN-filled primers. This work confirms the feasibility of a biomimetic adhesive design using PA–ACP/MSN in the primer phase without compromising immediate wettability and immediate μTBS up to 15 vol%. Remineralization is a potential capability that requires verification in future studies.

Hydrogels had gained considerable importance in drug delivery systems. Polyacrylic acid/acrylamide (AAc/AAm) and polyacrylic acid/acrylamide doped with magnetite (AAc/AAm)Fe 3 O 4 hydrogels have been prepared by ɣ -radiations and characterized by Fourier transform infrared spectra (IR), X-ray diffractions (XRD), scanning electron microscope (SEM) and transmittance electron microscope (TEM). The morphology and the particle size were determined from TEM images. The average particle size of Fe 3 O 4 was found to be 12 nm. The degree of cross-linking of Poly (AAc/AAm) hydrogel was determined from the gel fraction at different radiation doses and compositions. Swelling of the hydrogel was studied at different conditions. The magnetism of (AAc/AAm) Fe 3 O 4 was studied by vibrating sample magnetometer and the results indicated super-paramagnetic character of (AAc/AAm)Fe 3 O 4 . The band gap ( E g ) was determined and the values suggested semi-conductivity of the hydrogels. Doxorubicin loading and release by (AAc/AAm)Fe 3 O 4 hydrogel was studied and indicated that the hydrogel can load 78% of doxorubicin.