Deciphering Block Copolymers as Carriers of a Pyrazoline Derivative through Its Solvatochromic Behavior: A...

Many biologically active water-insoluble drug molecules have limited clinical application because of strong hydrophobicity. Recently triblock copolymers have attracted enormous interest as potential drug carriers. For the purpose of delivering the 5-(1-(bromohexa-1,3,5-triyn-1-yl)-3a,4,5,6,7,7a-hexahydro-1H-4,7-methanoindazol-3-yl)-3-methyl-1-phenyl-1H-pyrazole-4-carbonitrile (PYZ) molecule, triblock copolymers are used. In order to understand the delivery of this water-insoluble probe through triblock copolymers (TBP), the solvent-dependent fluorescence properties of this compound have been examined in different homogeneous solvents. Besides the experimental work, theoretical studies have also been conducted to explain actual orientation of atoms in PYZ through optimized structures to support the experimental findings. Moreover, the three TBP polymers P-123 (PEO₁₉ PPO₆₉ PEO₁₉ ), F-127 (PEO₁₀₀ PPO65PEO₁₀₀ ) and L-64 (PEO₁₃ PPO₃₀ PEO₁₃ ) have been treated here as potential carriers that encapsulate a pyrazoline derivative. The consequence of spatial captivity on the emission properties was systematically visualized by means of steady-state and time-resolved fluorescence spectroscopy. From DLS measurements the size variation with the polydispersity index of TBP in the presence and absence of PYZ in different triblock copolymers was also monitored. Furthermore these measurements have been supported by TEM imaging also.