## 4 Discussion  
In recent years, the administration of the drug after treatment of the infected area has become of major interest [33; 34] because infections can recur. Recent studies show that poly (lactic acid) (PLA) and poly (lactic-co-glycolic acid) (PLGA) are biocompatible and biodegradable polymers, being a good host for the incorporation of a wide variety of antimicrobial drugs. Antibiotic-loaded chitosan nanoparticles obtained by ionic gelation technique using TPP as a crosslinking factor are of durable stability. Entrapment of erythromycincin active molecules within the network of the polymer matrix implies more stable pharmaceutical formulation. This work was concerned with preparing a novel antibiotic carrier using PLA/PLGA nanoparticles loaded with erythromycincin using the W/O/W double emulsion solvent evaporation method [35]. Erythromycin-loaded PLA exhibited 340 nm in size, while drug-loaded PLGA nanoparticles revealed approximately 270 nm in size. Particle size distribution results indicated that the nanoparticle sizes are related to the concentration of the antibiotic used to load PLA/PLGA polymer. Electro-kinetic potential (zeta potential) refers to the difference in electric potential between the electric charge at the surface of a solid nanoparticle in the dispersion and the charge of the diffuse electric layer, denoting the degree of rejection of similarly charged nanoparticles in dispersion. A higher zeta potential for the obtained nano-composites disclosed the stability of colloidal dispersions resisting nanoparticles aggregation. The amount of the erythromycincin determined using HPLC analysis was expressed as sum of erythromycincin A, erythromycincin B, and erythromycincin C, resulting in 99.7% of the initial amount used to prepare the nanocomposites [36]. Antibiotic release profile revealed that erythromycincin release from Ery-PLA is faster than from Ery-PLGA nanocomposites. For the Ery-PLA sample, almost 50% of the antibiotic was rereleased within 4 h, and 75% was released within 2 days. For the Ery-PLGA sample,  
Figure 11: FTIR spectra of Ery-PLA and Ery-PLGA. approximately 50% of drug was controlled released within 8 h, while 75% was released within 3 days. As a consequence of these results, antibiotic binding to PLGA was stronger than to PLA polymer, indicating that PLGA-drug can be a better delivery system. Morphological characterization of erythromycininc encapsulated PLA and PLGA nanoparticles by scanning electron microscopy displayed spherical, rigid, and ring-shaped nanoparticles, as well as regular and isolated nanoparticles assigned to lactic content, which prevent aggregates formation. A correlation between the smooth surface and the lactic content which confer hydrophobicity to the polymer can be done. Moreover, due to the presence of lactic, the contact between particles becomes weaker, preventing agglomeration. A thermal analytical study indicated, for both samples, that pure drug has an endothermic peak at around 150 \({}^{\circ}\)C assigned to a melting point. The erythromycininc melting peak disappeared for both antibiotic encapsulated PLA/PLGA nanoparticles thermographs. This evidenced the existence of erythromycincin, showing a uniformly distribution of the drug throughout the host polymer. The thermographs also revealed a reduction in both polymers' transition temperature concerning nano-encapsulation of erythromycincin. That was owed to the increase of particles size, in the case of which glass transition temperature is inversely proportional to amorphous polymer's particles' size. Thermal analysis of antibiotic-loaded polymer as a drug delivery system is of importance since the processes used to samples preparation are able to modify the organization of the polymer chains [21]. Vibration spectrum of encapsulated antibiotic involves the type of interaction occurring between the active molecule and polymer due to the vibrations of the atoms' interaction, which can be modified in frequency and intensity.