Controlled and cellulose eco-friendly synthesis and characterization of Bi2O2CO3 quantum dot nanostructures (QDNSs) and drug delivery study

This work aimed to prepare solvent-free or green Bi2O2CO3 for quantum dot nanostructures (QDNSs) based on cellulose as a stabilizer and green capping agent to sorafenib delivery for liver targeting. Because the walnut tree is one of the most abundant trees in Iran, it was tried to synthesize Bi2O2CO3 QDNSs using a walnut skin extract. The saturation magnetization for Bi2O2CO3 QDNSs was calculated to be 68.1. Also, the size of products was measured at around 60–80 nm with the Debye–Scherrer equation. Moreover, the morphology, functional groups, and crystallography of the Bi2O2CO3 nanoparticles were investigated using atomic force microscopy, scanning electron microscopy, vibrating-sample magnetometer, and Uv–vis spectroscopy. The results demonstrated that Bi2O2CO3 QDNSs have opto-magnetic properties and they can be suggested as the candidate materials for the sorafenib delivery on the liver tissue. The optical band gap estimated for Bi2O2CO3 QDNSs was found to be red-shift from 3.22 eV. This study suggests the preparation of the Bi2O2CO3 QDNSs based on cellulose as new opto-magnetic materials at different temperatures of 180 °C, 200 °C, 220 °C, and 240 °C for sorafenib delivery as a type of biological therapy drug.

In the past three decades 1-3 , nanotechnology has seen significant advances in nanomaterials and new methods and materials. The liver is the hub of the metabolic activity of the body. With the advances in nanopharmaceutical sciences 4,5 , more goals have been pursued in service delivery structures to reduce the side effects of different drugs 6 , as well as improving drug delivery 7,8 in economically feasible ways 9 . Nanoparticle-based anti-cancer drugs have improved the treatment of various liver diseases and different types of cancer with drug targeting and imaging agents for liver cancer imaging. In particular, magnetic and optic Bi 2 O 2 CO 3 NPs-based delivery systems provide a good-looking method for localizing sorafenib as clinically important oral tyrosine kinase drugs in the liver using magnetic forces and optical effects. These drugs act at relatively long-range and do not affect most biological tissues. Sorafenib is an inhibitor for the treatment of various cancers 10 . With the development of new materials or methods, concern about environmental pollution has been doubled due to nanoparticles produced by chemical methods and the production of dangerous side-effects for in vivo preclinical imaging and drug discovery [11][12][13] . Therefore, there is a need for clean, non-toxic, and environmentally friendly green chemistry 14 . There are different physical and chemical methods for the synthesis of nanostructures in medicine such as chemical remediation 15,16 , lithography 17 , the ultrasonic method 18 , co-precipitation 19 , and microwave method 20 . The disadvantages of this method are the use of chemicals that act as restorative and stabilizing agents 21 . Nevertheless, these materials cause environmental pollution and these methods have a low production rate in high pressure and high energy during the reaction process 22 . Solvent-free synthesis as an eco-friendly useful approach 23 helps synthesize nano compounds 24 without using chemical and dangerous solvents 25 . The skin green walnut contains 13 phenolic compounds. Among these compounds, joggle is the most frequent and is the main ingredient in the green skin of walnut 26  www.nature.com/scientificreports/ is one of the best ways to control particle sizes and regular-shaped and well-crystallized nanocrystals 27 . Today, imaging of living organisms is one of the ways to intercept drugs to treat cancer cells and tumors in the body of living organisms 28 . Optical drug tracking is performed using various materials that have a high potential in optical properties 29 . Due to the opto-magnetic properties of nanoparticles, recent studies on the case using the nanostructures as career drugs have been expanded rapidly Table 1.
Because of their unique properties such as large surface to volume ratio and the quantum confinement effect 34 , nanoparticles exhibit corresponding changes in the emission properties 35 . The cellulose crystalline structures (CCS) act not only as a suitable substrate for the reductant agent of Bi 2 O 2 CO 3 QDNSs but also serves as the green capping agent and packaging factor. In this study, we report a new chemical processing without using any solvent (solvent-free method) for the synthesis of Bi 2 O 2 CO 3 QDNSs. This is a novel and useful opto-magnetic nanomaterial for sorafenib delivery for liver targeting in in-vivo imaging studies. The connection of Bi 2 O 2 CO 3 QDNSs to sorafenib provides opto-magnetic routing. The synthesized products were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDX), Atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis spectroscopy.

Results and discussion
These Bi 2 O 2 CO 3 QDNSs with opto-magnetic properties will enhance drug bioavailability and reduce dosing frequency and prevent hard and impossible treatment therapy. The structures of the suggested Bi 2 O 2 CO 3 /sorafenib formulation are illustrated in Fig. 1.

Crystallography.
To investigate the crystallographic properties and crystalline phases, the products were measured with X-ray diffraction (XRD) throughout the manufacturing process. The XRD patterns (10 < 2θ < 80) of cellulose nanocrystals and Bi 2 O 2 CO 3 nanocrystals in the cellulose base are shown in Fig. 2a,b, respectively. Using the XRD results, most of the reflection peaks can be indexed according to tetragonal phases with crystallographic parameters a = 5.468, b = 27.32, and c = 5.46 through the following lattice parameter formula (Eq. 1).
where h, k, and l are the crystalline face indexes. The specific surface area (S a ) of the Bi 2 O 2 CO 3 nanocrystals was obtained from the maximum intensity peak (112) while X-ray density (D x ) was calculated using Eqs. (2) and (3).
where N a is Avogadro number (6.023 × 1023 atoms/mole), M is molar weight, and a is the lattice parameter. Crystallography data show that nanoparticles are likely smaller if the nucleation rate is larger than the crystal growth rate. The results show that the obtained products lack any impurities. Based on the XRD data, the crystalline where D is the mean size of crystallites (nm), K is crystallite shape factor with approximate amount 0.9, λ is the X-ray wavelength, β is FWHM in radians of the X-ray diffraction peak, and θ is the Braggs angle (°).  CO 3 QDNSs show scale-like structures in the presence of the cellulose molecules. As can be seen, with increasing temperature, the density of scale-like structures will increase in the samples. As the temperature gradually rises to 200 °C, the Bi 2 O 2 CO 3 QDNSs grow on the cellulose surface and a large number of sheet structures can be found in the SEM images. In some areas, there is an overlap between the sheets. Cellulose molecules can play the role of the reductant agent and as a carbon source. Also, they can be responsible for control size and shape capping agent effects in the synthesis process of Bi 2 O 2 CO 3 QDNSs. Aggregation of nanoparticles occurs due to excessive nucleation at high temperatures. As a result, activation of the surfaces of the nanoparticles causes the product made from Bi 2 O 2 CO 3 QDNSs to have a larger particle size. It can be observed that Bi 2 O 2 CO 3 QDNSs synthesized at 220 °C on cellulose-based have more uniform size and shape and these samples have smaller particles size than other samples.

Morphological properties. EDX analysis is considered as a non
As temperature rises from 220 °C to 240 °C, the SEM image indicates an increase in the particle size of the products and generation of bulk Bi 2 O 2 CO 3 QDNSs on the cellulose substrate through the thermal decomposition (4) D = K /β cos θ www.nature.com/scientificreports/ method. In this process, due to the high surface area of the Bi 2 O 2 CO 3 QDNSs, the particle surfaces aggregated together and bulky structures are achieved when exposed to more heating.
Structural properties. Fourier transform infrared (FT-IR) spectrum is among the most important, nondestructive, and emerging tools that are widely used to identify organic (and in some cases inorganic) and functional groups in materials. FT-IR of Bi 2 O 2 CO 3 QDNSs and Bi 2 O 2 CO 3 /sorafenib formulation are shown in Fig. 4a,b, respectively. The broad absorption band centered at 1400-1450 cm −1 and 850 cm −1 correspond to the antisymmetric stretching mode of the CO 3 group in Bi 2 O 2 CO 3 nanostructures 36 . The absorption band appeared in the area 3300-3400 cm −1 is related to amine (N-H) bands in Bi 2 O 2 CO 3 /sorafenib formulation 37 .  Fig. 5a.
The results show that the Bi 2 O 2 CO 3 nanoparticles are distributed uniformly on the cellulose surface, leading to properties such as opto-magnetic performance. The root-mean-squared roughness (RMS) is an important parameter to introduce the roughness and softness and surface properties of the products. According to the AFM image data, R rms as the standard deviation factor is determined as follows (Eq. 5): where z n denotes the height of the nth data, ž shows the mean height of Z n in AFM topography, and N represents the number of data. For an area of 87.43 pm 2 , the roughness average is 14.62 nm. To assess the morphology and distribution size crystal of the product in the optimum condition (sample c), TEM images were studied (Fig. 5b). It can be observed from the TEM image that the Bi 2 O 2 CO 3 QDNSs (sample c) have uniform size and shape as the cellulose molecules appear in the range of 15-40 nm. The quantitative determination of the solutions, ions, and efficiency conjugated drug compounds were calculated using the Uv-vis spectroscopy. The magnetic properties of the samples were measured with a vibrating sample magnetometer (VSM). The Uv-vis spectroscopies of Bi 2 O 2 CO 3 QDNSs in different temperature conditions and Bi 2 O 2 CO 3 /sorafenib formulation samples are illustrated in Fig. 6a. The emission peaks at 252 nm in Bi 2 O 2 CO 3 nanostructures correspond to the exciton recombination. The emission peaks at 292 nm in Bi 2 O 2 CO 3 NPs/sorafenib formulation are related to oxygen deficiency and lattice distortion molecular interactions of Bi 2 O 2 CO 3 nanostructures and sorafenib. Magnetic properties of the nanoparticles' diamagnetic, paramagnetism, ferromagnets, antiferromagnets, and ferrimagnets materials are measured using the VSM. Figure 6b indicates the magnetization curve of the Bi 2 O 2 CO 3 / Sorafenib formulation in the air. Using magnetic properties in nanoparticles can create trackable and stable properties in various drugs and cause their interactions with cells or biological proteins, leading to the increased compatibility of drugs. The area within a loop represented in the hysteresis curve indicates magnetic energy loss. The B-H magnetic hysteresis curve for the Bi 2 O 2 CO 3 /sorafenib formulation indicates a very small hysteresis behavior for the samples. It also exhibits small values of coercivity field and remnant magnetization. The saturated magnetization (Bs) values and for Bi 2 O 2 CO 3 nanoparticles/sorafenib formulation at a magnetic field of 1.5 T was obtained to be 68.1 emu/g. The Bi 2 O 2 CO 3 nanostructure shows an obvious ferromagnetic behavior, suggesting the presence of the Bi molecule that can exist in the spinel systems. Bi 2 O 2 CO 3 /sorafenib formulation delivery. Initially, no optical properties were observed, but after 2 min, the image shows that the nano substance also contains the drug inside the liver. The evaluation showed that the synthesized material did not have a fatal effect. So, all organs were evaluated phenotypically to ensure that no damage was done to the target tissue and other organs. There was no change in the body tissues, espe-  www.nature.com/scientificreports/ cially the liver tissue. Therefore, it is suggested testing the levels of assurance of designs with different concentrations of Bi 2 O 2 CO 3 nanoparticles/sorafenib in a large number of in rates species, along with phenotypic and gene expression tests. The liver image of mice 2 min after injection and the same rate after 2 months later for the phenotypic investigation are illustrated in Fig. 7a,b, respectively. In cancer cells, glucose consumption is several times. Cancer cells can be detected by conjugated Bi 2 O 2 CO 3 QDNSs to glucose structures and tracking these structures in the body. Vertical all-glass Franz-type diffusion cell with an active surface area of 2.37 cm 2 and a receptor phase volume of 15 ml was used for the release study of sorafenib from Bi 2 O 2 CO 3 QDNSs at 37 ± 1 °C. Cellulose acetate dialysis membrane (Visking tube, MW cut-off 12,000 D) was used as a barrier between donor and receptor compartments of the diffusion cell. The receptor compartment was filled with normal saline solution (0.9%) and the donor compartment section was filled with 1 ml Bi 2 O 2 CO 3 nanoparticles/sorafenib. Free drug solutions were used as controls sample and empty Bi 2 O 2 CO 3 structures were examined as blanks. For this purpose, 1 ml sample was withdrawn at fixed time intervals from the receptor compartment, the same amount of fresh receptor medium was replaced, and the permeated drug concentration was measured. The cumulative release profiles of Bi 2 O 2 CO 3 /sorafenib formulation structures and Bi 2 O 2 CO 3 NPs are presented in Fig. 7c. The results indicate that after 240 min, 77.51% sorafenib was released from Bi 2 O 2 CO 3 /sorafenib formulation structures, while the amount of the drug released for sorafenib solution was 2.47%. The reason is that, due to the high surface area of the nanostructures, they absorb more amount drugs on their surface.

Conclusions
This study demonstrated that the Bi 2 O 2 CO 3 QDNSs can act as an optical and magnetical delivery platform for the tracing sorafenib by magnetic and optical targeting. In the present study, Bi 2 O 2 CO 3 QDNSs were synthesized and characterized as optical-magnetical carriers for sorafenib delivery in the living organism in the mice.  www.nature.com/scientificreports/

Material and methods
Chemicals and equipment. All the chemical and material reagents used in this study were used with no further purification as they were of pure and analytical grade. The starting reagent Bi(NO 3 ) 3 was purchased from SRL Company, India, and walnut shells were prepared from gardens around the Sirjan City of Iran. Sorafenib drug type was prepared from Loghman pharmaceutical and hygienic Co. The devices used in this study are as follows: X-ray diffractometer using Ni-filtered Cu-Ka radiation by a Rigaku D-max C III was used for XRD analysis. The EDS analysis was studied using the XL30 Philips microscope. For the morphological properties, SEM devices (JXA-8100, and JSM-6700F) were used. TEM (images were captured using a TEM Philips EM208 device with an accelerating voltage of 200 kV in the University of Shahid Bahonar Kerman, Iran. The FTIR spectrometer (550 Nicolet in KBr pellets) was recorded in the range of 400-4000 cm −1 . AFM for surface morphology study was done using an easy scan 2 Advanced Research AFM device. The particle size and particle distribution of the nanoparticles were determined by laser-light scattering (Mastersizer 2000E, Malvern Instruments, UK). In vivo imaging was obtained using in vivo imaging system F Pro model Kodak manufacturing company in the USA. The UV-visible spectrum of the product was recorded using a Scinco UV-vis scanning spectrometer (ModelS-4100).
Synthesis of cellulose nanocrystals. Initially, 1 g of dry walnut skin without any dust and moisture was used as the starting reagent. Then, the precursor was put into the external boat box-like and transferred to the furnace. The furnace temperature was set to 350 °C and the samples were heated for 8 h. After the heating process, the system was allowed to cool to room temperature naturally. The black precipitations were characterized by SEM and XRD.
Synthesis of Bi 2 O 2 CO 3 nanocrystals. In the next step, 0.4 g Bi(NO 3 ) 3 powder was completely ground in a porcelain mortar. Then, the powder was transferred to a crucible containing black brown precipitations cellulose crystals from the previous step. All these experiments were performed in the same way. The samples were heated in the furnace at different temperament conditions including 180 °C, 200 °C, 220 °C, and 240 °C for 4 h. After the thermal treatment in each step, the system was allowed to cool under argon atmosphere to room temperature naturally and the as-synthesized final precipitations were collected and were characterized by SEM, XRD, Uv-vis, and FT-IR.
Bi 2 O 2 CO 3 /sorafenib formulation. To prepare Bi 2 O 2 CO 3 /sorafenib formulation, 50 mg/l of as-synthesized Bi 2 O 2 CO 3 nanocrystals was solved in 20 ml distilled water. Also, 30 mg/l of sorafenib powder was solved in 10 ml of distilled water and ethanol solution with the ratio 2:1 and then was added dropwise to the above solution.
The pH was adjusted between 6 and 7.5 with a digital pH meter. Next, the mixture was placed under the reflux  www.nature.com/scientificreports/ Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creat iveco mmons .org/licen ses/by/4.0/.