研究目的
To design and synthesize N-aryl substituted azacalixphyrins with enhanced NIR absorption properties for use as photoacoustic contrast agents, overcoming limitations of existing organic dyes in the 700-850 nm range.
研究成果
Aryl-substituted azacalixphyrins were successfully synthesized, showing bathochromic shifts in absorption beyond 900 nm and enhanced photoacoustic responses under NIR excitation. These compounds are promising as organic contrast agents for photoacoustic imaging, with potential for use in the NIR transparency window of biological tissues. Future investigations should explore in vivo applications.
研究不足
The study is limited to in vitro experiments; in vivo applications were not tested. Instrumental limitations prevented measurement of full NIR absorption tails in some solvents. The impact of solvent nature and water content on absorption profiles requires careful control. Future work should focus on bio-imaging applications and potential toxicity assessments.
1：Experimental Design and Method Selection:
The study involved designing and synthesizing N-aryl substituted azacalixphyrins (ACPs) using a synthetic pathway similar to N-alkyl analogues, followed by characterization and evaluation of their absorption properties and photoacoustic (PA) response. Theoretical models (e.g., TD-DFT) were employed to predict and explain optical properties.
2：Sample Selection and Data Sources:
Samples included synthesized ACPs (compounds 1, 2, 3a-c) in various solvents (DMSO, MeOH, DMF, MeOH/H2O mixtures). Data were sourced from electronic absorption spectra, NMR spectra, pH-dependent absorption studies, and PA measurements.
3：List of Experimental Equipment and Materials:
Equipment included a flash column chromatography setup (alumina), spectrophotometers for absorption spectra, NMR spectrometers, a PA experimental setup with a laser tunable from 700 to 1000 nm, a flexible polymeric tube (TYGON?-3603), and an OptiCell? chamber. Materials included solvents (DMSO, MeOH, DMF, acetonitrile), reagents (N,N-diisopropylethylamine, hydrazine monohydrate, Pd/C, trifluoroacetic acid, DBU), and synthesized intermediates and macrocycles.
4：Experimental Procedures and Operational Workflow:
Synthesis involved steps from tetraaminobenzene hydrochloride intermediates to final ACPs via nucleophilic substitutions and reductions. Characterization included NMR, absorption spectroscopy in acidic and basic conditions, pH-dependence studies, and PA response measurements using a laser-excited setup with scanning and imaging.
5：Data Analysis Methods:
Data were analyzed using statistical processing for pKa calculations, comparison of absorption spectra and PA amplitudes, and normalization of PA signals. Software tools for theoretical modeling (e.g., TD-DFT) were used, as referenced.
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