Room temperature synthesis of biocompatible nano Zn-MOF for the rapid and selective adsorption of curcumin

a i D D 7, V Nanoscale metal-organic frameworks (MOFs) have appeared as potential materials in biomedical and IR revealed that the nanomaterial exhibited similar structure structural and other physical properties to tivity so that they can be utilized to develop electrochemical sensors. Interestingly, the active sites in the structure of high lications, zinc is a ts low cost [25,26]. ered as promising s the toxicity, the terials’ dispersion been many studies ano Zn-MOF ma- nd in Indian spices using overdosed peutic molecules. Therefore, much effort has been put into increasing the bioavailability and delivery of CUR through the design of drug carrier systems [41e43]. Herein, we demonstrate a fast room temperature preparation of nanoscale Zn-BDC-NH2 whose structure is built from octahe- dral Zn4O clusters and amine-functionalized terephthalate (BDC- NH2) linkers. Additionally, the nano Zn-BDC-NH2 containing NH2 * Corresponding author. Center for Innovative Materials and Architectures (INOMAR), Ho Chi Minh City, 721337, Viet Nam. E-mail address: dlhtan@inomar.edu.vn (T.L.H. Doan). Contents lists availab Journal of Science: Advanc .e l Journal of Science: Advanced Materials and Devices 5 (2020) 560e565Peer review under responsibility of Vietnam National University, Hanoi.been widely used as sensing materials in the field of electro- chemical detection [23e25]. MOFs possess an electrochemical ac- [18,19,38e40]. In addition, the low solubility in water of this polyphenolic hydrophobic substance has limited its use as thera-metal-containing nodes and organic linkers [1e5]. These materials have attracted appreciable attention for their potential applications in many areas, such as gas storage and separation [6e8], catalysis [9e11], sensing [12e14], environment treatment and biomedicine [15e19]. Recently, MOFs have been widely used as promising car- riers in drug delivery systems owing to their high drug loading capacity, biocompatibility, biodegradability, and robust function- ality [20e22]. Current advances in MOF synthesis for drug delivery applications relate to the size and shape control, the improvement of biocompatibility and biological stability. In addition, MOFs have Among many metals used in biological app common choice due to its low toxicity as well as i Therefore, Zn-MOFs have been recently consid materials for these applications [27e30]. Beside particle size plays an important role in the ma ability and biocompatibility [31,32]. There have reported on the synthesis and applications of n terials [33e37]. Curcumin (CUR) is a yellow bioactive compou and some drugs, but it is dangerous ifMetal-organic frameworks (MOFs) are a class of porous inorganic-organic hybrid materials which are constructed from give the potential to improve the performance of MOFs in the electrochemical detection.Available online 16 September 2020 Keywords: Curcumin Metal-organic frameworks Nano Zn-BDC-NH2 Fast adsorption Nano materials 1. Introductionhttps://doi.org/10.1016/j.jsamd.2020.09.009 2468-2179/© 2020 The Authors. Publishing services b ( original framework, but its particle size was very small of about 50 nm. As a result of the curcumin (CUR) adsorption investigation, the nanomaterial showed a high adsorption capacity on Zn-BDC-NH2 up to 179.36 mg$g
1 and faster adsorption in comparison with reported adsorbents. The results suggest that the nano Zn-BDC-NH2 MOF can be considered as a promising material for bio-applications. © 2020 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi. This is an open access article under the CC BY license ( porosity MOFs act as the enzyme-likes and are designed as nano- zymes in biosensor applications. The developments in nano MOFsReceived in revised form 10 September 2020 Accepted 14 September 2020sized MOF by using characterization techniques, including XRD, SEM, N2 isotherm sorption, TGA, and FT-Received 22 May 2020 sensing applications. In this work, a nano Zn-BDC-NH2 encoded MOF was effectively synthesized using the co-surfactants strategy and characterized for the curcumin adsorption. The analysis of the synthe-Original Article Room temperature synthesis of biocomp rapid and selective adsorption of curcum Y Thi Dang a, b, Minh-Huy Dinh Dang a, b, Ngoc Xuan Thang Bach Phan a, b, Hai Viet Le b, c, Tan Le Hoang a Center for Innovative Materials and Architectures (INOMAR), Ho Chi Minh City, 72133 b Vietnam National University-Ho Chi Minh City, Ho Chi Minh City, 721337, Viet Nam c University of Science, Ho Chi Minh City, 721337, Viet Nam a r t i c l e i n f o Article history: a b s t r a c t journal homepage: wwwy Elsevier B.V. on behalf of Vietnamtible nano Zn-MOF for the n at Mai a, b, Linh Ho Thuy Nguyen a, b, oan a, b, * iet Nam le at ScienceDirect ed Materials and Devices sevier .com/locate/ jsamdNational University, Hanoi. This is an open access article under the CC BY license functional groups will be a selective adsorbent for CUR with high capacity and fast adsorption. This results from the p-p interac- tion of nano Zn-BDC-NH2 and CUR as well as from the improvement of the material affinity with respect to CUR by introducing polar amine groups [19]. The aim of this work has been dedicated to the development of the novel nano MOF (Zn- BDC-NH2) with high biocompatibility, rapid and selective adsorption of CUR regarded to the application as a nanocarrier in CUR delivery systems or a sensing material for the detection of CUR. The nanomaterial was fully characterized by analysis tech- niques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), N2 isotherm sorption, thermogravi- metric analysis (TGA), and Fourier-transform infrared spectros- copy (FT-IR) to define its structural properties. Especially, kinetics and thermodynamics of CUR adsorption on Zn-BDC-NH2 were also investigated in this article. 2. Experimental centrifugation at 15,000 rpm in 20 min. The as-synthesized sample 15 min to separate the solids from the solutions. The supernatant solutions were analyzed for the absorbance at the wavelength l ¼ 420 nm via the UV-Vis spectrum. The remaining CUR concen- trations after adsorption were determined based on the linear function y ¼ a$x obtained from the calibration graph of the CUR solution at concentrations (from 0.3125 to 10 mg$L
1), and results are shown in Fig. S2, Supplementary Data. The point of zero charge (pHpzc) of the Zn-BDC-NH2 adsorbent was determined using the solutions with pH values between 2 and 11 adjusted by 0.1 N HCl or NaOH solutions. The initial and final pH values of the solutions before and after the adsorption process were measured and plotted to obtain the pHzpc. 3. Results and discussion 3.1. Synthesis and characterization The Zn-BDC-NH2 material is synthesized from the mixture of Zn(OAc) .2H O and H BDC-NH in the presence of surfactants, Y.T. Dang et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 560e565 561was washed with DMF (15  3 mL, each day) for 3 days and methanol (15  3 mL, each day) for 3 days. 2.2. CUR adsorption Nano Zn-BDC-NH2 was washed in DMF for 3 days, in methanol for 2 days and then activated in a vacuum system at 25 C for 12 h to remove the solvent from the pore of the material and used to conduct the adsorption experiments. In the adsorption experiment, for each given concentration of CUR (from 100 to 1600 mg L
1), 5 mg Zn-BDC-NH2 was dispersed in 5 mL of CUR ethanol solution with a pH of 7 and stirred at 25 C for 3 h. At the end of the adsorption process, the samples were centrifuged at 14,000 rpm for2.1. Synthesis of nano Zn-BDC-NH2 Nano Zn-BDC-NH2 was synthesized via a modified method re- ported previously [19]. Typically, a solution of H2BDC-NH2 (10.86 mg, 0.059 mmol), hexadecyltrimethylammonium bromide CTAB (10 mg, 0.027 mmol) and PVP (10 mg, 0.00025 mmol) was dissolved in 3 mL N,N-dimethylformamide (DMF). A solution of Zn(OAc)2.2H2O (35.12 mg, 0.16 mmol) was dissolved in DMF (2 mL) and quickly added to the above mixture under stirring and the whole was further stirred for 30 min. The product was collected byFig. 1. (a) PXRD analysis of Zn-BDC-NH2, the calculated pattern from the single crystal data image of Zn-BDC-NH2.2 2 2 2 CTAB and PVP, in DMF as the solvent and stirred at room temper- ature for 30 min. The obtained solid was washed with DMF three times and thenwas confirmed by PXRD shown in Fig. 1a. The PXRD result exhibits the characteristic peaks at 2q of 6.84, 9.69, 13.71, and 15.41, which are assigned to the (200), (220), (400), and (420) planes of Zn-BDC-NH2 structure, respectively. All the experimen- tally observed signals of the Zn-BDC-NH2 sample are the same as those of the Zn-BDC-NH2 structure calculated from reported data [44], indicating the pure phase of Zn-BDC-NH2. The Zn-BDC-NH2 material was then measured by SEM to determine the particle size. Fig. 1b shows the particle size of Zn-BDC-NH2 to be about 50 nm and there is a uniform size distribution. The results of both PXRD and SEM confirm that the Zn-BDC-NH2 nanomaterial has been successfully synthesized. The surface area and the pore size distribution of the materials can be typically obtained from the nitrogen adsorptionedesorption isotherms. The nitrogen isotherm of Zn- BDC-NH2 in Fig. 2a exhibits the type I isotherm and the BET (BrunauereEmmetteTeller) surface area was calculated to be 887 m2$g
1. The pore size distribution was calculated through the DFT method (see the inset of Fig. 2a) resulting in an average pore size of 13.25 Å. Thermogravimetric analysis (TGA) was carried out from room temperature to 700 C, and results are shown in Fig. 2b. According to the TGA curve, a low weight loss at a temperature(black) is compared to the experimental one of the Zn-BDC-NH2 sample and (b) SEM Fig. 2. (a) N2 isotherm at 77 K of activated Zn-BDC-NH2 and the pore-size distribution of Zn-BDC-NH2 (inset picture). (b) TGA curve of the activated Zn-BDC-NH2. Y.T. Dang et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 560e565562below 200 C can be attributed to the loss of solvent molecules, indicating that the material activation process has completely removed the solvent through the activation process. The weight loss (about 63%) occurs between 300 C to 485 C corresponding to the decomposition of the organic linkers. At temperatures higher than 485 C, no weight loss was observed, and the residue weight was that of the metal oxide of about 34.5%. 3.2. CUR adsorption We studied the effect of the initial CUR concentration and time on the adsorption capacity. Firstly, the effect of the CUR initial concentration on the adsorption process is illustrated in Fig. 3a. The experiment was performed by adding 5 mg Zn-BDC-NH2 to 5 mL CUR ethanol solution at different concentrations with a pH of 7 and continuous stirring at 25 C for 3 h. The results show that the adsorption capacity increases with the increasing CUR concentra- tion. Specifically, the adsorption capacity increases rapidly with the CUR concentration from 100 mg$L
1 to 800 mg$L
1 and increases slowly with the CUR concentration from 1000 mg$L
1 to 1600 mg$L
1. The qo value of the adsorption process derived is 179.36 mg$g
1. Secondly, the influence of the contact time to the CUR adsorption on the Zn-BDC-NH2 material at the concentration of 600 mg$L
1 was investigated. The adsorption of CUR on adsor- bents was studied over a contact time period from 15 to 180 min to determine the equilibrium time of adsorption. The result in Fig. 3b Fig. 3. (a) The effect of the CUR concentration on the adsorption capacities andshows that time of 180 min stirring is considered to be the equi- librium time for the adsorption process with a qe value of 113.98 mg$g
1. Fig. 4 shows the FT-IR spectra of the Zn-BDC-NH2, CUR, and CUR/ Zn-BDC-NH2 samples. The FT-IR analysis was performed to analyze the vibrations of Zn-BDC-NH2, CUR and confirmed the adsorption of CUR on the Zn-BDC-NH2 material. In the IR spectrum of Zn-BDC- NH2, the characteristic peak observed at 1571 cm
1 indicates the deprotonation of the COOH groups in 2-aminoterephthalic acid upon the reaction with metal ions [45]. In the CUR spectrum, the band at 3508 cm
1 corresponds to the OeH vibration of the phenolic group. Other characteristic peaks of the CUR molecule are observed at 1628 cm
1 (C]C vibration), 1602 cm
1 (benzene ring stretching vibration), 1509 cm
1 (C]O vibration), 1428 cm
1 (olefinic CeH bending vibrations), 1279 cm
1 (aromatic CeO stretching vibrations), and 1025 cm
1 (CeOeC stretching vibra- tions) [46,47]. Comparison between the CUR/Zn-BDC-NH2 and the Zn-BDC-NH2 spectra exhibits that the CUR/Zn-BDC-NH2 spectrum has three signals at 1509 cm
1, 1628 cm
1 and 3472 cm
1, corre- sponding to the C]O, C]C, and OeH groups of CUR, respectively. However, the stretching peak of the OeH group of CUR was red- shifted from 3508 to 3472 cm
1 in CUR/Zn-BDC-NH2 [48]. As the results of the FT-IR spectra, the presence of CUR in the CUR/Zn- BDC-NH2 sample was confirmed. In the kinetics study, the pseudo-first-order and pseudo- second-order kinetic models were used to calculated the reaction (b) effect of contact time on the adsorption rates of CUR on Zn-BDC-NH2. rate of CUR adsorption on Zn-BDC-NH2 (Section S3). The results of the CUR adsorption kinetics on Zn-BDC-NH2 in Fig. 5 reveal that the correlation coefficient value (R2) for the pseudo-second-order is higher than that of the pseudo-first-order, indicating that the adsorption fits the pseudo-second-order kinetic model and the reaction rate was 2.03  10
3 g$mg
1$min
1. The CUR adsorption capacity on the Zn-BDC-NH2 material and the reaction rate are compared with some of UiO-66 materials, as shown in Table 1. Based on Table 1, it is possible to show that the CUR adsorption The thermodynamics of the interaction between CUR and Zn- BDC-NH2 was analyzed to determine the thermodynamic quanti- ties DG, DH, and DS of the adsorption process. The thermodynamic process of adsorption is carried out at an initial CUR concentration of 600 mg$L
1 with stirring for 3 h at various temperatures. The values of the thermodynamic properties of the CUR adsorption on Zn-BDC-NH2 were calculated according to Eqs. (1) and (2) [49,50]: ln qe Ce ¼DS R
DH RT (1) DG¼DH
TDS; (2) where R is the universal gas constant (8.314 J$mol
1$K
1), T is the absolute temperature (K), DH is the enthalpy change (kJ/mol), DS is the entropy change (J/mol$K) and DG the free energy change (kJ/ mol). Based on the van't Hoff plot in Fig. 6, the thermodynamic values are calculated and shown in Table 2. The negative DG value in- dicates that the CUR adsorption on Zn-BDC-NH2 is the spontaneous reaction. The CUR adsorption on Zn-BDC-NH2 is an exothermic reaction with negative DH value. The positive DS value means that the randomness of the reaction system increases in the adsorption process. To study the surface charge properties of the zn-bdc-nh2 Fig. 4. FTIR spectroscopy of Zn-BDC-NH2 (red), CUR (blue) and CUR/Zn-BDC-NH2 (green). Right: corresponding picture of Zn-BDC-NH2, CUR, CUR/Zn-BDC-NH2 powders. Y.T. Dang et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 560e565 563capacity to Zn-BDC-NH2 is lower than that of Hf-UiO-66, Zr-UiO-66 and Zr-UiO-66 NH2 materials, these all could be due to the low surface area of Zn-BDC-NH2. However, the CUR adsorption on Zn- BDC-NH2 is 3 times faster than on the UiO-66materials [18,19]. This could result from the strong interaction of CUR and the amino- functionalized framework. It is noted that the CUR adsorption of the nano Zn-BDC-NH2 was significantly faster in comparison to the other nano MOFs.Fig. 5. (a) Pseudo-first-order and (b) pseudo-second-order Table 1 Adsorption capacities (qo) and reaction rate of CUR on Zn-BDC-NH2 and other MOFs. Nano MOF Particle size (nm) Surface area (m2$g
1) Averag Zn-BDC-NH2 50 887 13.25 Zr-UiO-66 30 1400 12.30 Hf-UiO-66 50e70 950 12.30 Zr-UiO-66 100e150 1276 10.50 Zr-UiO-66-NH2 100 1258 10.50adsorbent, the pH of point of zero charge (pHpzc) was determined. The graph of initial pH versus final pH of the solutions is shown in Fig. 7. The pHpzc can be determined via the point of intersection of the final pH line and the initial pH line. Accordingly, the pHzpc of zn- bdc-nh2 is about 7. This indicates that at pH values below 7, the surface of Zn-BDC-NH2 was positive, while at pH above 7, the sur- face was negative. This suggests the possibility of controlling the release of CUR at acidic pH. kinetics models for CUR adsorption on Zn-BDC-NH2. e pore size (Å) qo (mg$g
1) k2 (g$mg
1$min
1) Refs 179.36 2.03  10
3 This study 466.39 7.81  10
4 [10,11,18] 463.02 6.78  10
4 [10,18] 393.22 7.37  10
4 [10,11,19] 382.86 6.76  10
4 [10,19] cedY.T. Dang et al. / Journal of Science: Advan5644. Conclusion Nano Zn-BDC-NH2 has been successfully synthesized via the fast and room temperature reaction in the presence of surfactants, PVP, and CTAB. The synthesized nanomaterial with a particle size around 50 nm exhibited better CUR capture abilities than other materials. The maximum adsorption capacities of nano Zn-BDC- NH2 was 179.36 mg$g
1. Notably, kinetics investigation showed the CUR adsorption on the nano Zn-BDC-NH2 three times faster in comparison to the other MOF frameworks. Due to the formation of the hydrogen bond between the amine groups in the framework and the polar groups of CUR, the interaction between the nanoMOF and CUR has caused such a high adsorption capacity and fast adsorption. The results suggest that the nano amino-functionalized Zn-MOF could be considered to be a highly efficient adsorbent and can be used as a promising material for the design of novel drug- delivery systems or sensing material toward CUR. [11] L.H.T. Nguyen, T.T.T. Nguyen, Y.T. Dang, P.H. Tran, T.L.H. Doan, Microwave- doi.org/10.1007/s40820-018-0218-0. [15] T.L.H. Doan, H.L. Nguyen, H.Q. Pham, N.N. Pham-Tran, T.N. Le, K.E. Cordova, Fig. 6. The plot of ln (qe/Ce) vs 1/T of CUR adsorption on Zn-BDC-NH2. Table 2 Thermodynamic values of the CUR adsorption on zn-bdc-nh2 with initial concen- tration of 600 mg$L
1. MOF T (C) DGa (kJ/mol) Dha (kJ/mol) DSa (J/mol$k) zn-bdc-nh2 30
14.03
2.77 37.18 40
14.40 50
14.78 60
15.15 Fig. 7. Determination of the pH of point of zero charge (PZC) of Zn-BDC-NH2.Tailoring the optical absorption of water-stable ZrIV-and HfIV-based metaleorganic framework photocatalysts, Chem. Asian J. 10 (2015) 2660e2668, https://doi.org/10.1002/asia.201500641. [16] Z. Luo, S. Fan, J. Liu, W. Liu, X. Shen, C. Wu, Y. Huang, G. Huang, H. Huang, M. Zheng, A 3D stable metaleorganic framework for highly efficient adsorp- tion and removal of drug contaminants from water, Polymers 10 (2018) 209, https://doi.org/10.3390/polym10020209.[13] M.L. Hu, S.A.A. Razavi, M. Piroozzadeh, A. Morsali, Sensing organic analytes by metaleorganic frameworks: a new way of considering the topic, Inorg. Chem. Front. 7 (2020) 1598e1632, https://doi.org/10.1039/C9QI01617A. [14] Q. Qiu, H. Chen, Y. Wang, Y. Ying, Recent advances in the rational synthesis and sensing applications of metal-organic framework biocomposites, Coord. Chem. Rev. 387 (2019) 60e78, https://doi.org/10.1016/j.ccr.2019.02.009.Assisted synthesis as an efficient method to enhance the catalytic activity of Zr-based metal organic framework UiO-66 in a heterocyclization reaction, Asian J. Org. Chem. 8 (2019) 2276e2281, https://doi.org/10.1002/ ajoc.201900556. [12] X. Fang, B. Zong, S. Mao, Metaleorganic framework-based sensors for envi- ronmental contaminant sensing, Nano-Micro Lett. 10 (2018) 64, https://Declaration of competing interest The