## 4 Discussion  
In this study, drug-functionalized maleic anhydride copolymers based on ampicillin trihydrate and cephalexin monohydrate were synthesized for the first time by a chemical conjugation method. Chemical characterization of polymer-antibiotic conjugates was conducted by \({}^{1}\)H NMR and FTIR/ATR spectroscopies. These conjugates at different pH values with simulated body fluids over specified time intervals were analyzed, utilizing zeta and UV/VIS spectroscopic measurements. Parameters such as pH values, time duration and composition of solutions affected the absorbance of samples. The size of the particles of drug-functionalized maleic anhydride copolymers were on a sub-micro scale which has distinct benefits for administering drugs orally [35]. However, the particles of drugs became micro-sized in temporal and pH-dependent changes due to the aggregation of clusters among the particles. By the copolymer conjugation of antibiotics, the activity of drugs was extended over a longer time. DFMACs were stable in an extended pH range compared to the pure drugs. In general, DFMACs were more stable in the pH 2-6 band whereas drugs were unstable in acidic conditions and exposed to dissolution in gastric media. The activity and stability profiles of drugs were not aligned. On the other hand, DFMACs were stable when they exhibited a high activity profile. DFMACs demonstrated prolonged stability, activity and mobility and became efficient alternatives to the chosen drugs. Antibacterial tests proved that maleic anhydride copolymers acquired the bactericidal effect through antibiotic conjugation. The importance of antibacterial studies lay in the continuity of the antibacterial effect of drugs while enhancing pharmacokinetics through copolymer conjugation. The stability ranking of synthesized DFMACs were as follows: PMVEMA-AMP > PEMA-AMP > PIBMA-AMP and PMVEMA-CEF > PEMA-CEF > PIBMA-CEF. The hydrophilicity of the polymer significantly influenced the stability of DFMACs, with more hydrophilic polymers providing greater stability. Additionally, the PMVEMA was considered as highly reactive to primary amines and facilitates the formation of amide more rapidly [45] than the other copolymers. Hence, PMVEMA-AMP and PMVEMA-CEF were observed as the most stable drug-functionalized maleic anhydride copolymers. Regarding stability, activity and antibacterial efficiency, among the six different DFMACs studied, the most effective DFMACs overall were PMVEMA-conjugated drugs. The results demonstrated that the method of conjugation of the drug via an amide bond resulted in an improved macromolecular conjugate form, thereby improving the pharmacokinetics of the pharmacologically active substance. These DFMACs, chosen for two beta-lactam group antibiotics, exhibited better pharmacological properties and antibacterial activity compared to those found in the existing literature [46; 47]. As a result, it can be concluded that the developed PMVEMA-CEF and PMVEMA-AMP are promising drug delivery system candidates alternative to AMP and CEF in the treatment of microbial infections. Given the successful polymer conjugation with both AMP and CEF from different sub-groups of the \(\beta\)-lactam family, this methodology holds potential for application across the entire \(\beta\)-lactam group. The results suggested promising prospects for using these macromolecular conjugates in pharmaceutical technology, potentially as implants. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app14164112/s1](https://www.mdpi.com/article/10.3390/app14164112/s1)]([https://www.mdpi.com/article/10.3390/app14164112/s1](https://www.mdpi.com/article/10.3390/app14164112/s1)), Figure S1: NMR spectra of PMVEMA-AMP (a), PIBMA-AMP (b), PEMA-AMP (c), PMVEMA-CEF (d), PIBMA-CEF (e) and PEMA-CEF (f). Figure S2: Absorption spectra of AMP (a), PMVEMA-AMP (b), PIBMA-AMP (c) and PEMA-AMP (d) at different pH values.