Microparticle characterization
FTIR analysis was performed to evaluate the functional groups of the samples as well as the interaction between the components. Figure 1 depicts the FT-IR spectra of commercial Levodopa and GO. The primary absorption characteristic peaks of levodopa are 1416,1456,668 cm-1, representing alkenes group C = C vibration, 2851 and 2978 cm-1 showing C-H stretching vibration and NH2 stretches are visible at 1562 cm− 1. The FTIR spectra of graphene oxide exhibit peaks at 1051 cm− 1 and 1582 cm-1 representing C-O-H vibration mode and C = C bonds bending, respectively. The peak at 1720 cm− 1 is assigned to the carboxyl group.
Figure 2 (A) depicts FONP absorbance bands observed around 578cm-1 and 614cm-1. These bands indicate the stretching of the Fe-O bond in the Fe3O4 crystalline lattice. Usually, the expected bands for Fe3O4 are observed around 370 cm-1 and 570 cm-1. However, a shift was observed in their wavenumbers due to their nano size. They are characteristically pronounced for all spinel structures and ferrites. In FTIR spectra of the Fe3O4-GO composite depicted in Figure 2(B), a peak is seen at 598 cm-1 attributed to Fe-O vibrational mode, and 1616 cm-1 represents C=C alkene; these peaks could be attributed to the formation of Fe3O4- GO composite.
Figure 3 depicts the FT-IR spectra of SAl-LSA, LD 2, SAl-LSA-Fe, and LD 4. SAl-LSA FTIR spectra show the following absorbance peaks at 1045 cm-1 representing C-O group elongation, 1420 cm-1 representing a symmetric stretching of COO groups, 654 cm-1 representing C-H bend in alkenes and 1619 cm-1 depicts conjugated carbonyl stretching. SAl-LSA-LD (LD 1) FTIR spectra show the following absorbance peak at 1040 cm-1 representing C-O group elongation, and 1420 cm-1 shows a sharp peak representing a symmetric stretching of COO, indicating the presence of SAl-LSA. A characteristic peak of levodopa is seen at 2934 cm-1, representing carboxylic acid O-H stretching, which was initially found at 2978 cm-1, showing a hypochromic shift due to the interaction of levodopa with the polymer blend containing SAl-LSA. SAl-LSA-Fe FTIR Spectra showed peaks at 609 cm-1 attributed to Fe-O vibrational mode. 1049 cm-1 represents C-O group elongation, and 1619 cm-1 depicts conjugated carbonyl stretching, indicating the presence of SAl-LSA. SAl-LSA- Fe-LD (LD 2) FTIR Spectra showed a lower-intensity peak at 616 cm-1 attributed to Fe-O vibrational mode, and a characteristic peak of levodopa was seen at 2934 cm-1 representing carboxylic acid O-H stretching. An absorbance peak at 1043 cm-1 represents C-O group elongation, and the conjugated carbonyl stretching at 1619 cm-1 indicates the presence of SAl-LSA.
Figure 4 depicts the FT-IR spectra of SAl-LSA-GO, LD 3, SAl-LSA-Fe-GO, and LD 4. SAl-LSA-GO FTIR spectra show peaks at 1583 cm-1, representing C-OH bending, which is characteristic of GO. Conjugated carbonyl stretching at 1619 cm-1 and absorbance peak at 1043 cm-1 represent C-O group elongation, indicating the presence of SAl-LSA. SAl-LSA-Fe-GO FTIR Spectra, 1040 cm-1, represents C- O group elongation and conjugated carbonyl stretching at 1619 cm-1, indicating the presence of SAl- LSA. 1563 cm-1 represents C-OH bending, showing the presence of GO and a lower-intensity peak at 609 cm-1 attributed to Fe-O vibrational mode. SAl-LSA-GO-LD FTIR spectra show peaks at 1563 cm-1, representing C-OH bending, showing the presence of GO. 1420 cm-1 represents a symmetric stretching of COO groups, and 1619 cm-1 depicts conjugated carbonyl stretching, indicating the presence of SAl-LSA. Levodopa characteristic peak was observed at 2978 cm-1, representing carboxylic acid O-H stretching. SAl-LSA-Fe- GO- LD FTIR spectra show peaks at 1033cm-1 representing C-O group elongation, and 1619 cm-1 depicts conjugated carbonyl stretching, indicating the presence of SAl-LSA. 1559 cm-1 represents C-OH bending, showing the presence of GO, and the levodopa characteristic peak observed at 2978 cm-1 represents carboxylic acid O-H stretching.
Thermogravimetric analysis
Thermogravimetry analysis (TGA) of the blends is shown in Fig. 5. The TGA blend demonstrated a two-step weight loss due to SAl and LSA. The first weight loss of roughly 21% at 30–200°C was caused by moisture evaporation and loss of water content. The complexity of the procedure was responsible for the second weight loss of roughly 30% in the 200–250°C range. Lignin is a complex structure made up of carbonyl, benzylic, and phenolic hydroxyl groups. When subjected to high temperatures ranging from 200°C to 400°C, the process of lignin breakdown occurs. At temperatures above 400°C, lignin pyrolysis leads to the decomposition and condensation of aromatic rings. In the blends LD2 and LD4, When the mass loss for Fe3O4 is raised to high temperatures, products containing O2 may develop as a result of magnetite oxidation processes into hematite (4Fe3O4 + O2 = 6Fe2O3). When the temperature rises over 300°C in GO-containing blends LD3 and LD4, a substantial fall in the amount of GO by 20–30% is attributed to the disintegration of hydroxyl groups, epoxy, and carboxyl oxygen-containing functional groups on the surface of the GO, reducing its quality. At temperatures above 270°C, levodopa thermal breakdown resulted in two weight-loss events in all blends. The first sharp incident happened at 280°C-300°C with a weight loss caused by levodopa breakdown. The combustion of levodopa is responsible for the second weight loss at 380°C-600°C.
X-ray diffraction studies
Figure 6 shows that the iron oxide phase occurs in 3 samples, LD 2, LD 4, and LD5, with no other sub-family. Spectral peaks are visible and distinctly associated with Fe NP. The XRD spectra of SAl-LSA observed a major peak of 2θ OF 14.55. Bragg reflections for LD7, which are levodopa and carbidopa at 18.49°and 22.33°, are observed as reported in the literature; this shows that the drug exists in crystalline form. In LD1, LD2, LD3, and LD4, Levodopa may have been intercalated into the interlayer of the nanocomposite because the X-ray diffraction pattern of the nanocomposite lacked the drug's typical reflections. This confirmed that the drug is present as amorphous solid dispersions within the polymeric blend. For LD 6, according to published research, the characteristics of the carbon peak for GO occurred at 26° and 16°.
Surface morphology
As depicted in Fig. 7, the surface morphology and shape of the magnetic nanoparticles coated were investigated using a FESEM. The FESEM investigation supports the effect of the coating chemicals on the morphology of the IONP. The photos show that the IONP was spherical and had a narrow particle size distribution. When used in medication delivery applications, the nano size and distribution of IONP solution particles can contribute to their stability.
The excellent absorbability of IONP during germination is attributed to its extremely energetic and active surface. A surface agent allows embranchments to approach the surface, coating the IONP rapidly. As a result, agglomeration was avoided, particle size was maintained, and particle growth was limited.
This proved the capability of reducing particle size using a surface coating. In the current approach, polymers surround the surface immediately after creating IONP, preventing particle aggregation indirectly.
Aggregations are inescapable due to factors such as interparticle interactions and magnetic field interactions while washing, which generate agglomerates and secondary structures. When coatings are added to the surface, these structures are partially broken up, and the polymer is loaded onto their surface. During the exchange phase, anions of nitrate replace the interlayer-bound drugs, generating particle clumping and agglomeration via surface attachment.
As shown in Fig. 8, The SEM-EDX analysis shows all ionic concentrations. Iron, oxygen, carbon, barium, and chlorine elements are all present in the synthesized blends LD2 and LD4. According to the table in Figure C, the atomic percentages of iron oxide, oxygen, carbon, barium, and chlorine for FONP coated with SAl-LSA are 56.2%, 21.5%, 11.9%, 8.2%, and 1.8%, respectively, compared to 3.8%, 19.1%, 33.2%, 39.8% and 1.8% for IONP coated with SAl-LSA-GO as depicted figure D. The carbon peak in LD4 is caused by graphene oxide, the crosslinking agent phase causes the barium and chlorine peaks, and the iron oxide nanoparticles cause the iron peak.
Loading effectiveness of polymeric film
After removing the polymeric films from the drug solution, the remaining solution underwent UV spectroscopy at 280 nm analysis to determine the levodopa concentration. The loading efficiency was calculated by subtracting the concentration of LD free in the supernatant (Ct) from the initial LD concentration (C0) and dividing by C0.
l𝑜𝑎𝑑i𝑛𝑔 𝑒ffi𝑐i𝑒𝑛𝑐𝑦 (%) =
We used UV spectrophotometry to determine that levodopa loaded 68.41%, 63.07%, 69.67%, and 57.18% efficiently into LD 1, LD 2, LD 3, and LD 4 films at pH 7.4. The loading efficiency of the films was better than the previously reported work of 60% loading efficiency13. Being made of graphene oxide, LD 3 had the best loading efficiency. This is because it increased the surface area of the polymeric films, which gave the levodopa more room to bind. The drug loading efficiencies of the film in decreasing order are as follows: LD 3 > LD 1 > LD 2 > LD 4.
Invitro release of Levodopa
The release profiles of levodopa from the polymeric films were studied in a solution with a pH of 7.4 that was meant to mimic the environment in the brain. There was a significant difference seen in the release profiles of polymeric films. The amount of LD that was released was computed. The drug release (%) from the films was determined using the formula mentioned below.
Release (%) = M/M x 100
Mt = concentrations /amount of drug released
at the time (t)
Mi = initially loaded drug content
From the graphical representation shown in Fig. 9, A shows the release profile of levodopa from LD 1 for 48 hours. In the first 10 minutes, a 4.8% release was seen. The release percentages increased about 20% every 2 hours in the initial 6 hours, indicating a faster release of levodopa from the polymeric film. It was observed that 78% of the drug was released within 30 hours. After 48 hours, it was observed release values dropped from 78–50%. It was indicating that the drug was degraded.
B shows the release profile of levodopa from LD 2 for 48 hours. An external magnet was placed under the beaker containing film and PBS. In the first 10 minutes, 15% release of levodopa was seen, which is higher than LD 1. About 43% of the drug was released in 48 hours, showing a controlled release of levodopa in the presence of a magnetic field. The presence of Fe3O4 led to the slow and controlled release of levodopa in the presence of a magnetic field.
C shows the release profile of levodopa from LD 3 for 48 hours. In the first 10 minutes, 3% release of levodopa was seen, which was lesser than LD 1 and LD 2. About 24% of the drug was released in 48 hours, showing a controlled release of levodopa much better than LD 1 and LD 2. The controlled release could be attributed to the functional groups of graphene oxide, which influence the release of levodopa from the films.
D shows the release profile of levodopa from LD 4 for 48 hours. In the first 10 minutes, 9% release of levodopa was seen, which is lesser than LD 2. About 28% of the drug was released in 48 hours, showing a controlled release of levodopa much better than LD 1 and LD2. Both GO and Fe3O4 influence the controlled release of levodopa. Therefore, a magnetic hydrogel with graphene oxide will be suitable for the release of the levodopa in a controlled -sustained manner.