Reagents and Materials
Poly(lactic-co-glycolic acid) (PLGA) with a 50:50 monomer ratio and a specified molecular weight was used as the polymer matrix. [Name of the model drug, e.g., curcumin or another appropriate compound] was used as a model hydrophobic active pharmaceutical ingredient (API). Polyvinyl alcohol (PVA, 87–89% hydrolysis grade) was used as an emulsion stabilizer. Organic solvents (dichloromethane, acetone) and buffer solution components were of analytical grade or higher.
Synthesis of Drug-Loaded Nanoparticles
PLGA nanoparticles (NPs) containing the model drug were prepared using the water-in-oil-in-water (w/o/w) double emulsion solvent evaporation method. Briefly, the aqueous inner phase solution was emulsified into a solution of PLGA and the hydrophobic drug in an organic solvent (dichloromethane) using an ultrasonic homogenizer to obtain a primary (w/o) emulsion. The resulting emulsion was slowly introduced into an outer aqueous phase containing a stabilizer (PVA) under continuous stirring to form a secondary (w/o/w) emulsion. The organic solvent was removed by evaporation under reduced pressure using a rotary evaporator. The resulting nanoparticles were collected by centrifugation, washed three times with distilled water to remove excess PVA and unencapsulated drug, and then lyophilized for subsequent storage.
The encapsulation efficiency (EE%) was determined using an indirect method. For this purpose, the NP suspension was centrifuged, and the supernatant was analyzed for free drug content using high-performance liquid chromatography (HPLC). The EE% was calculated using the following formula:
$$\text{EE}\% = \frac{\text{Total amount of drug} – \text{Amount of free drug}}{\text{Total amount of drug}} \times 100\%$$
In Vivo Pharmacokinetics and Biodistribution Studies
Experiments were conducted on male Wistar rats (weighing 200–250 g). The animals were housed under standard vivarium conditions with free access to food and water. All procedures were performed in accordance with ethical standards for the care and use of laboratory animals.
The animals were randomized into two groups ($n=6$ per group). The first group (control) received an intravenous injection (via the tail vein) of the free drug solution, while the second group was administered an equivalent dose of the drug encapsulated in PLGA NPs.
