Development of Biodegradable Packaging Films Embedded with Microencapsulated Nanosensors Responsive to Spoilage Gases (e.g., Volatile Amines) with Dynamic Color Change

The convergence of biodegradable polymer technology with nanoscale sensing architectures presents a disruptive paradigm in active and intelligent food packaging, enabling real-time spoilage detection through molecularly selective gas-sensing mechanisms. This study reports the fabrication and functional optimization of poly(lactic acid)–starch composite films embedded with microencapsulated nanosensors capable of chemoselective recognition of volatile amines—principal spoilage metabolites in proteinaceous food matrices—via dynamic chromophoric transitions. The nanosensors were engineered through coacervation-based microencapsulation of halochromic dye–functionalized mesoporous silica nanoparticles (MSNs), further surface-modified with organosilane linkers to enhance dispersion stability and interfacial compatibility within the biopolymeric matrix. The encapsulation system was specifically tuned to yield pH-sensitive chromophore release upon amine adsorption-induced alkalization, facilitating optical signaling in the visible spectrum. Fabrication of the films was accomplished via solvent casting under controlled humidity and temperature to preserve the microcapsule structural integrity and ensure homogeneous spatial distribution. The physicochemical and morphological properties of the films were characterized through Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Thermal stability was evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), while mechanical performance was assessed via tensile testing according to ASTM D۸۸۲ standards. Gas–film interaction kinetics were quantitatively examined by exposing films to controlled atmospheres containing ۰–۲۰۰ ppm of trimethylamine and dimethylamine at ۴ ± ۱ °C, with spectral data captured by UV–Vis reflectance spectroscopy and quantified using CIELab colorimetric parameters (ΔE*, a*, b*). The microencapsulation approach exhibited a mean encapsulation efficiency of ۸۷.۴ ± ۲.۱%, with responsive chromatic shifts occurring within ۴.۲ ± ۰.۳ minutes post-exposure to ≥۵۰ ppm volatile amines. Colorimetric response intensity demonstrated a logarithmic correlation (R² > ۰.۹۸) with amine concentration, indicating robust quantitative sensing capability. Furthermore, in situ application tests on chilled fresh fish fillets confirmed that the films exhibited early spoilage detection up to ۳۶ hours prior to olfactory recognition, correlating with microbial total viable counts exceeding ۷ log CFU/g. The biodegradable nature of the composite matrix achieved complete degradation (≥۹۵%) within ۶۰ days under controlled composting conditions, underscoring its environmental compatibility. These findings substantiate the potential of microencapsulated nanosensor-integrated biodegradable films as next-generation intelligent packaging systems, enabling proactive spoilage monitoring and extending the operational capacity of cold-chain logistics.

کلیدواژه ها:

Biodegradable ، Nanosensor ، Microencapsulation ، Volatile Amines ، Dynamic Color Change ، Smart Packaging