Neighboring Hydroxyl Research Articles

Metal-free production of natural blue colorants through anthocyanin–protein interactions

IntroductionThe scarcity of naturally available sources for blue colorants has driven reliance on synthetic alternatives. Nevertheless, growing health concerns have prompted the development of naturally derived blue colorants, which remains challenging with limited success thus far. Anthocyanins (ACNs) are known for providing blue colors in plants, and metal complexation with acylated ACNs remains the primary strategy to generate stable blue hues. However, this approach can be costly and raise concerns regarding potential metal consumption risks. ObjectivesOur study aims to introduce a metal-free approach to achieve blue coloration in commonly distributed non-acylated 3-glucoside ACNs by exploring their interactions with proteins and unveiling the underlying mechanisms. MethodsUsing human serum albumin (HSA) as a model protein, we investigated the structural influences of ACNs on their blue color generation using visible absorption spectroscopy, fluorescence quenching, and molecular simulations. Additionally, we examined the bluing effects of six proteins derived from milk and egg and identified the remarkable roles of bovine serum albumin (BSA) and lysozyme (LYS). ResultsOur findings highlighted the importance of two or more hydroxyl or methoxyl substituents in the B-ring of ACNs for generating blue colors. Cyanidin-, delphinidin- and petunidin-3-glucoside, featuring two neighboring hydroxyl groups in the B-ring, exhibited blue coloration when interacting with HSA or LYS, driven primarily by favorable enthalpy changes. In contrast, malvidin-3-glucoside, with two methoxyl substituents, achieved blue coloration through interactions with HSA or BSA, where entropy change played significant roles. ConclusionOur work, for the first time, demonstrates the remarkable capability of widely distributed 3-glucoside ACNs to generate diverse blue shades through interactions with certain proteins. This offers a promising and straightforward strategy for the production of ACN-based blue colorants, stimulating further research in this field.

The radical scavenging activity of monocaffeoylquinic acids: the role of neighboring hydroxyl groups and pH levels.

Caffeoylquinic acids (CQAs) are well-known antioxidants. However, a key aspect of their radical scavenging activity - the mechanism of action - has not been addressed in detail thus far. Here we report on a computational study of the mechanism of activity of CQAs in scavenging hydroperoxyl radicals. In water at physiological pH, the CQAs demonstrated ≈ 104 times higher HOO˙ antiradical activity than in lipid medium (k(lipid) ≈ 104 M-1 s-1). The activity in the aqueous solution was determined by the hydrogen transfer mechanism of the adjacent hydroxyl group (O6'-H) of the dianion states (Γ = 93.2-95.2%), while the single electron transfer reaction of these species contributed 4.8-6.8% to the total rate constants. The kinetics estimated by the calculations are consistent with experimental findings in water (pH = 7.5), yielding a kcalculated/kexperimental = 2.4, reinforcing the reliability and precision of the computational method and demonstrating its utility for evaluating radical reactions in silico. The results also revealed the pH dependence of the HOO˙ scavenging activity of the CQAs; activity was comparable for all compounds below pH 3, however at higher pH values 5CQA reacted with the HOO˙ with lower activity than 3CQA or 4CQA. It was also found that CQAs are less active than Trolox below pH 4.7, however over pH 5.0 they showed higher activity than the reference. The CQAs had the best HOO˙ antiradical activity at pH values between 5.0 and 8.6. Therefore, in the physiological environment, the hydroperoxyl antiradical capacity of CQAs exhibits similarity to renowned natural antioxidants including resveratrol, ascorbic acid, and Trolox.

Atomic layer deposition mechanism of hafnium dioxide using hafnium precursor with amino ligands and water

As a unique nanofabrication technology, atomic layer deposition (ALD) has been widely used for the preparation of various materials in the fields of microelectronics, energy and catalysis. Hafnium dioxide (HfO2), as an excellent high-κ oxide, is widely used as a substitute gate dielectric for conventional SiO2 in field effect transistor devices. Currently, HfO2 high-κ gate dielectric in MOSFET devices was prepared via ALD technology using tetrakis(dimethylamino)hafnium(IV) (Hf(NMe2)4, TDMAHf) and water (H2O) as the precursors. In this work, the complicated surface reaction mechanism of HfO2 H2O-based ALD using Hf(NMe2)4 was investigated using density functional theory calculations. In the TDMAHf reaction, the dimethylamino group of the precursor was eliminated by ligand exchange reaction with the hydroxyl group on the surface. Subsequently, a second dimethylamino group of TDMAHf could further be eliminated by another hydroxyl group on the surface. In the H2O reaction, ligand exchange reactions and coupling reactions could both occur. By the ligand exchange reactions, water molecule could react with the dimethylamino group on the surface. Simultaneously, the hydroxyl and amino groups could also react with neighboring hydroxyl groups to eliminate dimethylamine and water molecules via the coupling reactions. All these insights into the complicated surface reaction mechanism of H2O-based ALD could promote the further development of ALD chemistry and materials.

Effect of composition and structure of ethylene-vinyl acetate copolymer on its alcoholysis kinetics: A combined experimental and DFT study

The alcoholysis process of ethylene–vinyl acetate copolymer (EVA) is both important and complex. In this work, we conduct experimental and computational investigations to examine the alcoholysis kinetics and mechanism of EVA with an ethylene content if less than 50 mol%. Our findings indicate that the overall structure of EVA polymer chain has little effect on the alcoholysis rate. However, the local structure of the acetate group, particularly its association with the ethylene content, significantly affects the overall alcloholysis. To predict the influence of ethylene content on the overall rate constant, we propose an empirical model based on detailed kinetic studies of triads. Additionally, we discover a self-acceleration phenomenon in EVA alcoholysis, although it is less pronounced compared to polyvinyl acetate. Furthermore, we employed quantum chemical calculation using density functional theory (DFT) to confirm the effect of structure on EVA alcoholysis. Notably, we investigate, for the first time, the influence of neighboring hydroxyl group on self-acceleration phenomenon through theoretical calculations. This work offers valuable insight into EVA alcoholysis and may serve as a guide for exploring its mechanism and designing processes for producing EVA related polymer materials.

Synergistic interaction of Cu(II) with caffeic acid and chlorogenic acid in α-glucosidase inhibition.

Phenolic acids are widespread in foods and are beneficial to human health. However, the role of metal ions in influencing the binding of proteins with phenolic acids that contain the same parent nucleus structure remains unclear. This study investigated the inhibitory effect of caffeic acid (CA) and chlorogenic acid (CHA) on α-glucosidase and the biological effect of copper on this process. It was found that the esterification of CA with quinic acid could increase the fluorescence quenching, conformational change, and inhibitory effect of CHA on α-glucosidase. Copper ions reduced their fluorescence quenching and conformation-changing ability by binding to the neighboring phenolic hydroxyl group but also increased their ability to alter secondary structure and to inhibit α-glucosidase and in vitro anti-glycation. Overall, this study shows that the binding of copper ions to the phenolic hydroxyl group adjacent to CA and CHA synergistically inhibited α-glucosidase. The findings will offer a theoretical basis for investigating the properties of metal ions and phenolic acid in food chemistry and their potential applications in the prevention and treatment of diabetes mellitus. © 2023 Society of Chemical Industry.

Reduced Chitosan as a Strategy for Removing Copper Ions from Water.

Toxic heavy metals are priority pollutants in wastewater, commonly present in dangerous concentrations in many places across the globe. Although in trace quantities copper is a heavy metal essential to human life, in excess it causes various diseases, whereby its removal from wastewater is a necessity. Among several reported materials, chitosan is a highly abundant, non-toxic, low-cost, biodegradable polymer, comprising free hydroxyl and amino groups, that has been directly applied as an adsorbent or chemically modified to increase its performance. Taking this into account, reduced chitosan derivatives (RCDs 1-4) were synthesised by chitosan modification with salicylaldehyde, followed by imine reduction, characterised by RMN, FTIR-ATR, TGA and SEM, and used to adsorb Cu(II) from water. A reduced chitosan (RCD3), with a moderate modification percentage (43%) and a high imine reduction percentage (98%), proved to be more efficient than the remainder RCDs and even chitosan, especially at low concentrations under the best adsorption conditions (pH 4, RS/L = 2.5 mg mL-1). RCD3 adsorption data were better described by the Langmuir-Freundlich isotherm and the pseudo-second-order kinetic models. The interaction mechanism was assessed by molecular dynamics simulations, showing that RCDs favour Cu(II) capture from water compared to chitosan, due to a greater Cu(II) interaction with the oxygen of the glucosamine ring and the neighbouring hydroxyl groups.

Smartphone-assisted dual-channel discriminative detection of Hg(II) and Cu(II) ions with a simple, unique, readily available probe

Heavy metal ions are well-known atmospheric and environmental pollutants and cause long-term damage to humans. Mercury is one of the most toxic and hazardous one that induce critical motor disorders and a variety of diseases. Likewise, excess copper can lead to Alzheimer’s and Parkinson’s disease, as well as various other health conditions. Therefore, selective and sensitive methods for determining and visualizing mercury and copper remain necessary. In our study, we developed the first-ever optical-electrochemical method of discriminatively detecting Hg2+ and Cu2+ ions using 1-thioglycerol (TG)-modified gold nanoparticles (AuNPs) and by altering the solution’s medium. Adding Hg2+ ions to AuNP–TG in ultrapure water changed the original burgundy color blue, the initial absorbance value (i.e., 520 nm) decreased, and a new absorbance peak appeared at λmax = 670 nm. In a phosphate-buffered solution, Cu2+ ions issued a similar response. However, neither Hg2+ nor Cu2+ ions exhibited cross-reactivity under those sensing conditions. The optical mechanism for detecting both metal ions seems to have relied on the destabilization and aggregation of AuNPs. On the one hand, the electrochemical detection of Cu2+ stemmed from the reduction of the complex between Cu2+ and TG’s neighboring hydroxyl groups in the probe, whereas the electrochemical detection of Hg2+ stemmed from the fact that Hg2+ broke the AuNP–S bond, after which the AuNPs clustered and significantly increased the electrode’s electron transfer rate. Last, because the method involves using a smartphone to read signals without requiring professional equipment, it considerably decreases the cost of detection and shows promise for the rapid on-site detection of Hg2+ and Cu2+ ions.

Kinetics Study of Acid-Catalyzed Sulfate Esterification Reactions for Atmospherically Relevant Polyols

Extensive laboratory and field studies have identified organosulfates as important constituents of secondary organic aerosol (SOA). However, the mechanisms by which these organosulfates form in the atmosphere remain uncertain. The rate constants for the acid-catalyzed sulfate esterification reactions of a series of polyols were measured via bulk kinetics experiments using nuclear magnetic resonance (NMR) spectroscopy. The NMR data indicated that while reactions that occurred at a terminal hydroxyl site were somewhat faster than reactions at internal hydroxyl sites, there were no other significant structure–reactivity trends among the series of polyols. These results suggest that neighboring hydroxyl groups do not significantly modify the sulfate esterification rates from those previously determined for monoalcohols. Extrapolation of the kinetics data to typical atmospheric SOA acidities suggests that sulfate esterification reactions of polyols are unlikely to be a significant source of organosulfates. This conclusion is consistent with a previous study of monoalcohols which made similar conclusions about the kinetic infeasibility of this reaction type.

Fragmentation and Ionization Efficiency of Positional and Functional Isomers of Paeoniflorin Derivatives in Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Paeoniflorin and albiflorin, which are functional isomers, are the major constituents of an herbal medicine derived from Paeonia lactiflora. Those functional isomers and their galloylated derivatives, which are positional isomers, were studied by matrix-assisted laser desorption/ionization–tandem mass spectrometry (MALDI-MS/MS). The resulting mass spectra are discussed based on the fragmentation patterns of the sodium adducts. The product ion spectra of 4-O-galloylalbiflorin and 4′-O-galloylpaeoniflorin differed, even though they were positional isomers. The fragmentations of the ester parts were influenced by the neighboring hydroxyl groups. The ionization efficiency of the sodium adduct of albiflorin was higher than that for paeoniflorin. These results indicate that the carboxylic ester group has a higher affinity for sodium ions than the acetal group, which can be attributed to the carbonyl oxygen being negatively polarized, allowing it to function as a Lewis base.

Tuning the electron transfer events in a series of cyanide-bridged [Fe2Co2] squares according to different electron donors.

It has been recognized that both the ligand fields and intermolecular interactions may greatly impact the electron-transfer-coupled spin transition (ETCST) events in switchable magnetic materials; however, the engineering of these factors within a given system is still challenging. In this article, we chose the 4,4'-substituent 2,2'-bipyridine derivatives as chelating ligands according to their increasing electron-donating strength and incremental potential for forming hydrogen bonds (bpyCHO,CH3(L1) < bpyCH2OH,CH3 (L2) < bpyCH2OH,CH2OH (L3)), and prepared three new [Fe2Co2] complexes, {[(Tp*)Fe(CN)3Co(L)2]2[ClO4]2}·Sol (1, L = L1, Sol = 4MeCN·2H2O; 2, L = L2, Sol = 3MeCN; 3, L = L3, Sol = 4MeOH; Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate). X-ray crystallography studies revealed that all the complexes share similar cyanide-bridged [Fe2Co2] square compositions except for the different substituted groups of L ligands, which led to the clearly evidenced intercluster hydrogen bonds between the neighbouring hydroxyl groups in 2 and 3. As a result, 1 remained in the paramagnetic [FeIII,LS2CoII,HS2] state over the whole temperature range, while 2 and 3 showed complete ETCST behaviour with the transition temperatures (T1/2) being 221 and 294 K, respectively.

Remarkably enhanced dynamic oxygen migration on graphene oxide supported by copper substrate

The dynamic covalent properties of graphene oxide (GO) are of fundamental interest to a broad range of scientific areas and technological applications. It remains a challenge to access feasible dynamic reactions for reversibly breaking/reforming the covalent bonds of oxygen functional groups on GO, although these reactions can be induced by photonic or mechanical routes, or mediated by adsorbed water. Here, using density functional theory calculations, we demonstrate the remarkably enhanced dynamic oxygen migration along the basal plane of GO supported by copper substrate (GO@copper), with C-O bond breaking reactions and proton transfer between neighboring epoxy and hydroxyl groups. Compared to reactions on GO, the energy barriers of oxygen migrations on GO@copper are sharply reduced to be less than or comparable to thermal fluctuations, and meanwhile the crystallographic match between GO and copper substrate induces new oxygen migration paths on GO@copper. This work sheds light on understanding of the metal substrate-enhanced dynamic properties of GO, and evidences the strategy to tune the activity of two-dimensional-interfacial oxygen groups for various potential applications.

Supported MXene/GO Composite Membranes with Suppressed Swelling for Metal Ion Sieving.

Novel two-dimensional (2D) membranes have been utilized in water purification or seawater desalination due to their highly designable structure. However, they usually suffer from swelling problems when immersed in solution, which limits their further applications. In this study, 2D cross-linked MXene/GO composite membranes supported on porous polyamide substrates are proposed to improve the antiswelling property and enhance the ion-sieving performance. Transition-metal carbide (MXene) nanosheets were intercalated into GO nanosheets, where the carboxyl groups of GO combined the neighboring hydroxyl terminal groups of MXene with the formation of -COO- bonds between GO and MXene nanosheets via the cross-linking reaction (−OH + −COOH = −COO− + H2O) after heat treatment. The permeation rates of the metal ions (Li+, Na+, K+, Al3+) through the cross-linked MXene/GO composite membrane were 7–40 times lower than those through the pristine MXene/GO membrane. In addition, the cross-linked MXene/GO composite membrane showed excellent Na+ rejection performance (99.3%), which was significantly higher than that through pristine MXene/GO composite membranes (80.8%), showing improved ion exclusion performance. Such a strategy represents a new avenue to develop 2D material-derived high-performance membranes for water purification.

A Tough and Self-Healing Polymer Enabled by Promoting Bond Exchange in Boronic Esters with Neighboring Hydroxyl Groups

A Tough and Self-Healing Polymer Enabled by Promoting Bond Exchange in Boronic Esters with Neighboring Hydroxyl Groups

Molecular dynamics study on water and ions transport mechanism in nanometer channel of 13X zeolite

Understanding the atomistic transport within nanoporous zeolite is essential in a broad field. Herein, molecular dynamics was systematically utilized to elucidate the migration mechanism of pure water and NaCl solution in the 13X zeolite. At nano-scale level, molecular simulation clearly distinguishes the wetting and saturating stages of water transport in porous zeolite. The interior skeleton of 13X zeolite provides plenty of oxygen sites with strong polarity, which attracts frontier water molecules to infiltrate the hydrophilic zeolite surface rapidly in nearly 2 ns. The ladder-like ingress curve for water molecules highlight the discontinuous remain-jump wetting process that is induced by the competition adsorption with oxygen sites between the subsequent water molecules and the front water molecules. Initial wetting on interior surface reduces significantly the permeability of subsequent water transport. Furthermore, the penetrated water molecules, competing oxygen sites with extra-framework cations, can cause cations to exhibit different hydration behavior. Additionally, the permeability of water flux throughout zeolite channel is reduced by 10% as the Na+ and Cl- are incorporated in solution. Na+ with large hydration shells are sieved by bottlenecks formed by the windows of 12-ring structure with a diameter of 7.38 Å. The accumulated Na+ at the entrance region associate with neighboring water molecules and hydroxyl oxygen atoms to form hydrated clusters and ionic pairs, which plays as a physical barrier in blocking water transport. Decoding of the transport mechanism of water and salt solutions in zeolites at the molecular level facilitates breaking the existing upper limit of energy storage density and water treatment efficiency.

Docking Study of Naringin Binding with COVID-19 Main Protease Enzyme

The Coronavirus Disease (COVID-19) has recently emerged as a human pathogen caused by SARS-CoV-2 virus was first reported from Wuhan, China, on 31 December 2019. Upon study, it has been used molecular docking to binding affinity between COVID-19 protease enzyme and flavonoids with evaluations based on docking scores calculated by AutoDock Vina. Results showed that naringin suppressed COVID-19 protease, as it has the highest binding value than other flavonoids including quercetin, hesperetin, garcina and naringenin. An important finding in this study is that naringin with neighboring poly hydroxyl groups can serve as inhibitors of COVID-19 protease bind to the S pocket of protein, it is shown that residues His163, Glu166, Asn142, His41and PHe181 participate in the hydrogen bonding and pi-pi interactions, the same as happened with decahydroisoquinolin as a novel scaffold for SARS 3CL protease inhibitors.In other hand, some of the known protease inhibitors and anti-influenza drugs docked with COVID-19 protease, it has low binding value than naringin

Reinforcement of ‘imine-hydroxyl chelation pocket’ by encapsulating into the β-CD cavity for the sterically protective detection of Al3+

The effect of encapsulating a schiff base probe; o-phenolnaphthylimine (pni) into β-cyclodextrin (β-CD) and its impact on the detection of Al3+ was investigated using the spectrofluorometric technique. The impact of imine moiety and the neighbouring hydroxyl groups of pni in the sensing of Al3+ were assessed through the experimental and computational procedure. The role of ‘imine-hydroxyl chelation pocket’ of pni in the detection of Al3+ was estimated, correlated and demonstrated. FTIR, NMR and mass spectral techniques were used for the investigations in solid state. Stoichiometry of the complexes was estimated using UV–visible and fluorescence spectral techniques in liquids state. Molecular modeling and steric maps were obtained using 3D structural data of compounds. Linearity range, LOD and LOQ were estimated from the selectivity and sensitivity studies. The proposed work demonstrates the impact of additional binding centers that has to be considered while designing a chemosensor for metal cations.

Mechanism and quantitative assessment of saturation transfer for water-based detection of the aliphatic protons in carbohydrate polymers.

CEST MRI experiments of mobile macromolecules, for example, proteins, carbohydrates, and phospholipids, often show signals due to saturation transfer from aliphatic protons to water. Currently, the mechanism of this nuclear Overhauser effect (NOE)-based transfer pathway is not completely understood and could be due either to NOEs directly to bound water or NOEs relayed intramolecularly via exchangeable protons. We used glycogen as a model system to investigate this saturation transfer pathway in sugar polymer solution. To determine whether proton exchange affected saturation transfer, saturation spectra (Z-spectra) were measured for glycogen solutions of different pH, D2 O/H2 O ratio, and glycogen particle size. A theoretical model was derived to analytically describe the NOE-based signals in these spectra. Numerical simulations were performed to verify this theory, which was further tested by fitting experimental data for different exchange regimes. Signal intensities of aliphatic NOEs in Z-spectra of glycogen in D2 O solution were influenced by hydroxyl proton exchange rates, whereas those in H2 O were not. This indicates that the primary transfer pathway is an exchange-relayed NOE from these aliphatic protons to neighboring hydroxyl protons, followed by the exchange to water protons. Experimental data for glycogen solutions in D2 O and H2 O could be analyzed successfully using an analytical theory derived for such relayed NOE transfer, which was further validated using numerical simulations with the Bloch equations. The predominant mechanism underlying aliphatic signals in Z-spectra of mobile carbohydrate polymers is intramolecular relayed NOE transfer followed by proton exchange.

Comparison of the Effect of Acids in Solvent Mixtures for Extraction of Phenolic Compounds From Aronia melanocarpa

Thirty-two different solvent mixtures containing methanol and acid (acetic, formic, and hydrochloric); methanol, water, and acid; and pure methanol were tested for their efficiency for extraction of phenolic compounds from aronia ( Aronia melanocarpa) belonging to the groups of anthocyanins, flavonols, and hydroxycinnamic acid derivatives. Thirteen compounds were detected and quantified in the extracts using HPLC/DAD/ESI-MS n. The yield of each compound and group was evaluated with regard to the extraction solvent composition. Extraction mixtures containing HCl were superior to the ones containing acetic or formic acid for the extraction yield of total phenolic compounds, which was especially pronounced for anthocyanins. The solvent mixture containing methanol/water/HCl (90:8:2, v/v/v) gave best results for the qualitative and quantitative assay of anthocyanins. However, this solvent mixture caused O-methylation of 3- and 5-caffeoylquinic acids transforming them to 3- and 5-feruloylquinic acids, respectively, during extraction. This peculiar finding must be taken into account during sample preparation for the analysis of polyphenols in any sample. It was observed that this O-methylation is specific for dihydroxycinnamic acid compounds containing neighboring hydroxyl groups. These results suggest the need for a detailed study of the behavior of various polyphenolic compounds during extraction with solvent mixtures containing methanol/HCl since it is very often used for the analysis of anthocyanins.

Molecular investigation of adsorption behaviors of hydroxyl-terminated polybutadiene (HTPB) binders onto copper surface: The effects of aluminum nanoparticles

The adherent behaviors of hydroxyl-terminated polybutadiene (HTPB), a typical high viscosity liquid widely used as a binder in rocket motor propellants, onto the copper (Cu) surfaces with/without the interference of Al nanoparticles were investigated by classical molecular dynamics (MD) simulations. The results indicate that HTPB molecules adsorbed directly onto Cu(001) surface exhibit the tendency to distribute parallel to the 〈110〉 crystal direction family as a result of tense atom arrangement along the close-packed crystal directions. The dynamic hydrogen-bonded network, formed by inter-/intra-molecular interactions among neighbouring hydroxyl groups, is also suggested to exert strong influence on the distribution of HTPB molecules. Moreover, Al nanoparticles have been proved to be readily enveloped by HTPB chains when placed close to the pure high viscosity liquid, which will in turn restrict the mobility of HTPB molecules, eventually resulting in the decrease of wettability of HTPB droplet on Cu surface. The flow slip behavior of HTPB liquid on Cu surface, regardless of the presence of Al nanoparticles, was tested and directly compared by confined shear simulations. The Al hemispheres, acting as convex obstacles on the flat surface, seem to be capable of suppressing the slippage of chain-like HTPB molecules, which will be easily entangled by local protrusions. Therefore, it can be inferred that the flow behavior and interfacial wettability of high viscosity liquid will be largely influenced by the discontinuous solid-phase particles dispersed in it.

Gallate-induced nanoparticle uptake by tumor cells: Structure-activity relationships.

How nanoparticles interact with biological systems determines whether they can be used in theranostic applications. It has been demonstrated that tea catechins, may enhance interactions of magnetic nanoparticles (MNPs) with tumor cells and the subsequent cellular internalization of MNPs. As part of the chemical structure of the major tea catechins, gallates are found in a variety of plants and thus food components. We asked whether the structure of gallate might act as a pharmacophore in the enhancement of the effects of MNP-cell interactions. Uptake of dextran-coated MNPs by glioma cells and cell-associated MNPs (MNPcell) were respectively analyzed by confocal microscopy and a colorimetric iron assay. Co-incubation of MNPs and gallates, such as gallic acid and methyl gallate, induced a concentration-dependent increase in MNPcell, which was associated with co-localization of internalized MNPs and lysosomes. An analysis of the structure-activity relationship (SAR) revealed that the galloyl moiety exerted the most prominent enhancement effects on MNPcell which was further potentiated by the application of magnetic force; catechol coupled with a conjugated carboxylic acid side chain displayed comparable effects to gallate. Blockade or reduction in the number of hydroxyl groups rendered these compounds less effective, but without inducing cytotoxicity. The SAR results suggest that neighboring hydroxyl groups on the aromatic ring form an essential scaffold for the uptake effects; a similar SAR on antioxidant activities was also observed using a free radical-scavenging method. The results provide pivotal information for theranostic applications of gallates by facilitating nanoparticle-cell interactions and nanoparticle internalization by tumor cells.