Synthesis, Characterization, Biodegradation, and in Vitro Photodynamic Activities of Silicon(IV) Phthalocyanines Conjugated Axially with Poly(ε-caprolactone)

Abstract

A new series of phthalocyanine-containing biodegradable poly(ε-caprolactone)s have been synthesized by ring-opening polymerization of ε-caprolactone and/or 5-ethylene ketal ε-caprolactone using silicon phthalocyanine dihydroxide as the initiator and tin(II) 2-ethylhexanoate as the catalyst. The polymers have been spectroscopically characterized, and their molecular weights have been determined by gel permeation chromatography (GPC). All the polymers exhibit typical electronic absorption and fluorescence characteristics for nonaggregated phthalocyanines. The singlet oxygen quantum yields of selected polymers have been determined and found to be slightly lower than that of unsubstituted zinc(II) phthalocyanine in N,N-dimethylformamide (DMF). Nanoparticles with an average hydrodynamic radius 〈R h〉 of ∼87 nm have been prepared from the homo-poly(ε-caprolactone) 3a and 3b (bulk) via a microphase inversion method. The ketal-containing analogues 5−7 are able to form nanoparticles with a smaller dimension (〈R h〉 = 26−46 nm) in the absence of surfactants. The biodegradation of these systems with Lipase PS has been monitored by a combination of static and dynamic laser light scattering together with fluorescence spectroscopy, which shows that phthalocyanine rings are released during degradation. The polymers exhibit a high phototoxicity toward the HepG2 cancer cell line. The results suggest that this novel polymer-based colloidal system is potentially useful for the delivery and release of photosensitizers in photodynamic therapy.

Thermosensitive copolymer with cobalt phthalocyanine and catalytic behavior based on adjustable LCST

“…The aggregation tendency of the dendritic phthalocyanines decreases as the size of the dendrons increases [9][10][11][12][13]; however, it is very difficult to realize catalyst recovery and recycling by this method. The strategy of immobilizing MtPc on selected insoluble supports (such as activated charcoal, zeolite or clay) has been introduced and used to prepare polymeric MtPc catalysts and thereby to facilitate catalyst separation and recycling, which reduces effluent contamination [14][15][16][17][18].…”

Octa-armed star-shaped poly(ε-caprolactone)s with a phthalocyanine core by ring-opening polymerization: Synthesis and characterization

“…Upon excitation at 671 nm, 5-7 exhibited a fluorescence emission peak at λ = 711, 710 and 712 nm, respectively, with a Stokes shift of 0-2 nm, near the fluorescence emission peak of 4 at λ = 710 nm. It can be concluded that under the polymerization conditions in this study, the luminescence property of the phthalocyanine core is protected[36,57,58]. As in electronic spectra case, the fluorescence intensity decreased with increasing [M]/[I] ratio, probably due to the decrease of the percentage of the phthalocyanine core in the total sample solution.…”

“…In the UV-vis absorption spectra of 4-7, Q-band absorptions were observed as a single narrow band of high intensity at 705, 705, 704 and 703 nm, respectively, with shoulders at a slightly higher energy side of the Q band, typical for non-aggregated phthalocyanines. The Q-band absorption values did not significantly change for the whole series of ZnPc-containing star polymers 5-7, which suggested that the length of the polymeric substituent does not significantly perturb the π-electron system[36,67]. InFig.…”

“…Their derivatives are attracting considerable attention in many applications, such as in chemical sensors [28], photodynamic therapy [29], electrochromic displays [30], Langmuir-Blodgett films [31], information storage systems [32], non-linear optics [33] and liquid crystals [34] due to their extensive delocalised 18π-electron system and intense absorption in the visible region at 600-800 nm (called Q band) and high quantum yield of excited triplet states [35]. Molecular arrangement is a substantial element for examining the characteristics of phthalocyanine materials, which can be feasible by the incorporation with a macromolecule [36]. In addition, the incorporation of a phthalocyanine ring into a macromolecular matrix or the conjugation of phthalocyanine with polymer chains is a technique for designing new polymeric compounds with special properties [37].…”

“…To the best to our knowledge, there are no studies reported on the synthesis of star-shaped PCL, which is peripherally linked to a phthalocyanine core by the ROP, except for the study of Ng et al, in which PCL chains are axially linked to silicon(IV) phthalocyanine dihydroxide [36].…”