Syntheses and properties of a series of cationic water-soluble phthalocyanines

A series of symmetrical cationic phthalocyanines (Pcs) with either Zn(II) or Si(IV) metal ions and two bulky axial ligands on the silicon complexes was synthesized in high yields. The photophysical (absorption, emission, fluorescence, and singlet oxygen quantum yields) and cellular (uptake, toxicity, and subcellular localization) properties of this series of Pcs were investigated. The Si(IV)-Pcs exist mainly as monomers in aqueous media and have higher fluorescent quantum yields in protic solvents (methanol and water) than the Zn(II)-Pcs. The presence of eight short PEG groups at the periphery of a Zn(II)-Pc significantly increases its solubility in protic solvents, but a centrally chelated silicon ion and associated bulky axial ligands were more efficient in preventing aggregation of the Pc macrocycles. The singlet oxygen quantum yields for this series of Pcs in DMSO are in the range 0.09-0.15. All Pcs were readily taken up by human HEp2 cells, and the extent of their accumulation within cells depends on their hydrophobic character. Intracellularly, all Pcs localized preferentially within the cell lysosomes. The Zn(II)-Pc 11 and Si(IV)-Pcs 12 and 14 were found to be the most phototoxic (IC50 = 2.2 microM at a 1 J cm(-2) light dose) of this series of compounds.     

Preparation and improvement of release behavior of chitosan microspheres containing insulin

Sophisticated delivery systems, such as nanoparticles, represent a growing area in biomedical research. Nanoparticles (Np) were prepared using a solvent emulsion evaporation method (SEEM) to load zinc(II) phthalocyanine (ZnPc). Np were obtained using poly (d,l latic-co-glycolic acid) (PLGA). ZnPc is a second generation of photoactive agents used in photodynamic therapy.

ZnPc loaded PLGA nanoparticles were prepared by SEEM, characterized and available in cellular culture. The process yield and encapsulation efficiency were 80 and 70%, respectively. The nanoparticles have a mean diameter of 285 nm, a narrow size distribution with polydispersive index of 0.12, smooth surface and spherical shape. ZnPc loaded nanoparticles maintains its photophysical behavior after encapsulation. Photosensitizer release from nanoparticles was sustained with a moderate and burst effect of 15% for 3 days. The photocytotoxicity of ZnPc loaded PLGA Np was evaluated on P388-D1 cells what were incubated with ZnPc loaded Np (5 μM) by 6 h and exposed to red light (675 nm) for 120 s, and light dose of 30 J/cm². After 24 h of incubation, the cellular viability was determined, obtaining 61% of cellular death. All the physical–chemical, photophysical and photobiological measurements performed allow us conclude that ZnPc loaded PLGA nanoparticles is a promising drug delivery system for photodynamic therapy.     

Photodynamic therapy and nuclear imaging activities of zinc phthalocyanine‐integrated TiO2 nanoparticles in breast and cervical tumors

In recent years, phthalocyanines (Pcs) have been widely used as photosensitizer in photodynamic therapy applications. Because of their strong absorptions in the near‐infrared region (640–700 nm). The integration of phthalocyanine derivatives to a nanoparticle is expected to be efficient way to improve the activity of the photosensitizer on the targeted tissue. It is known that the integrated molecules not only show better accumulation on tumor tissue but also reduce toxicity in healthy tissues. In this study, the ZnPc molecule was synthesized and integrated to the TiO₂ nanoparticle, to investigate the potential of PDT and its cytotoxicity. Additionally, ZnPc and ZnPc‐TiO₂ molecules were labeled with ¹³¹I and it was aimed to put forth the nuclear imaging/therapy potentials of ¹³¹I labeled ZnPc/ZnPc‐TiO₂ by determining in vitro uptakes in mouse mammary carcinoma (EMT6), human cervical adenocarcinoma (HeLa). In result of our study, it was observed that the radiolabeling yields of the synthesized ZnPc and ZnPc‐TiO₂ with ¹³¹I were quite high. In vitro uptake studies shown that ¹³¹I‐ZnPc‐TiO₂ could be a potential agent for nuclear imaging/treatment of breast and cervical cancers. According to PDT results, ZnPc‐TiO₂ might have as to be a potential PDT agent in the treatment of cervical tumor. ZnPc and ZnPc‐TiO₂ might be used as theranostic agents.     

Delivery of the photosensitizer Pc 4 in PEG–PCL micelles for in vitro PDT studies

The silicon phthalocyanine Pc 4 is a second-generation photosensitizer that has several properties superior to other photosensitizers currently approved by the FDA, and it has shown significant promise for photodynamic therapy (PDT) in several cancer cells in vitro and model tumor systems in vivo. However, because of the high hydrophobicity of Pc 4, its formulation for in vivo delivery and favorable biodistribution become challenging. To this end, we are studying encapsulation and delivery of Pc 4 in block copolymer micelles. Here, we report the development of biocompatible PEG–PCL micelle nanoparticles, encapsulation of Pc 4 within the micelle core by hydrophobic association with the PCL block, and in vitro PDT studies of the micelle-formulated Pc 4 in MCF-7c3 human breast cancer cells. Our studies demonstrate efficient encapsulation of Pc 4 in the micelles, intracellular uptake of the micelle-formulated Pc 4 in cells, and significant cytotoxic effect of the formulation upon photoirradiation. Quantitative estimation of the extent of Pc 4 loading in the micelles and the photocytotoxicity of the micelle-incorporated Pc 4 demonstrate the promise of our approach to develop a biocompatible nanomedicine platform for tumor-targeted delivery of Pc 4 for site-selective PDT. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2386–2398, 2010     

Photocytotoxicity of mTHPC (Temoporfin) Loaded Polymeric Micelles Mediated by Lipase Catalyzed Degradation

PURPOSE: To study the in vitro photocytotoxicity and cellular uptake of biodegradable polymeric micelles loaded with the photosensitizer mTHPC, including the effect of lipase-catalyzed micelle degradation. METHODS: Micelles of mPEG750-b-oligo(epsilon-caprolactone)5 (mPEG750-b-OCL5) with a hydroxyl (OH), benzoyl (Bz) or naphthoyl (Np) end group were formed and loaded with mTHPC by the film hydration method. The cellular uptake of the loaded micelles, and their photocytotoxicity on human neck squamous carcinoma cells in the absence and presence of lipase were compared with free and liposomal mTHPC (Fospeg). RESULTS: Micelles composed of mPEG750-b-OCL5 with benzoyl and naphtoyl end groups had the highest loading capacity up to 30% (w/w), likely due to pi-pi interactions between the aromatic end group and the photosensitizer. MTHPC-loaded benzoylated micelles (0.5 mg/mL polymer) did not display photocytotoxicity or any mTHPC-uptake by the cells, in contrast to free and liposomal mTHPC. After dilution of the micelles below the critical aggregation concentration (CAC), or after micelle degradation by lipase, photocytotoxicity and cellular uptake of mTHPC were restored. CONCLUSION: The high loading capacity of the micelles, the high stability of mTHPC-loaded micelles above the CAC, and the lipase-induced release of the photosensitizer makes these micelles very promising carriers for photodynamic therapy in vivo.     

Investigation of In vitro PDT Activities and In vivo Biopotential of Zinc Phthalocyanines Using 131I Radioisotope

Novel octylthio‐containing asymmetrically substituted Zn(II) phthalocyanine (Zn(II)Pc1) and a symmetric derivative (Zn(II)Pc2) have been prepared to investigate the biological potential and ability to photosensitize singlet oxygen for photodynamic therapy applications. In this study, the singlet oxygen generation potential and in vitro photodynamic activities of these compounds have been tested. Both ZnPcs reveal to be very efficient singlet oxygen generators and promising PSs for PDT applications. In vitro PDT activities of the compounds were evaluated in EMT‐6 murine mammary carcinoma and HeLa human cervix carcinoma cell lines. Moreover, Zn(II)Pc1 displayed the phototoxic effects in the mammary cancer cell line (6.25 μm concentration at 30 J/cm² light dose and 12.5 μm concentration at 20 J/cm² light dose), while Zn(II)Pc2 did not show any phototoxic effects both in two cell lines. Zn(II)Pcs were radiolabeled with ¹³¹I in high yields. Biodistribution studies revealed that the radiolabeled Zn(II)Pc1 showed significant uptake in l. intestine, pancreas, brain, and ovary, while Zn(II)Pc2 has significant uptake in ovary and pancreas in normal rats. Hence, these Pcs derivatives could be promising candidate for tumor nuclear imaging.     

Preparation, characterization, photocytotoxicity assay of PLGA nanoparticles containing zinc (II) phthalocyanine for photodynamic therapy use

Nanoparticles containing Zinc (II) Phthalocyanine (ZnPc) were prepared by a spontaneous emulsification diffusion method utilizing poly-(D,L lactic-co-glycolic acid) (PLGA), characterized and available in cellular culture. The process yield and encapsulation efficiency were 60% and 80%, respectively. The nanoparticles have a mean diameter of 200 nm, a narrow size distribution with polydispersive index of 0.15, smooth surface and spherical shape. ZnPc loaded nanoparticles maintain their photophysical behaviour after the encapsulation process. Photosensitizer released from nanoparticles was sustained with a burst effect of 10% for 3 days. The photocytotoxicity was evaluated on P388-D1 cells. They were incubated with ZnPc loaded Np by 6 h and exposed to light (675 nm) for 120 s, and light dose of 30 J cm-2. After 24 h of incubation, the cellular viability was determined, obtaining 60% of cellular death. All the physical-chemical and photobiological measurements performed allowed one conclude that ZnPc loaded PLGA nanoparticles are a promising drug delivery system for PDT.     

Zinc phthalocyanine encapsulated in polymer micelles as a potent photosensitizer for the photodynamic therapy of osteosarcoma

Zinc phthalocyanine (ZnPc) is a highly potent second-generation photosensitizer for cancer photodynamic therapy (PDT) with attractive photo-physical and photo-chemical properties. However, poor solubility and strong trend of crystallization prevent it from loading in most of drug delivery systems and hamper its further application. Herein, to overcome this problem, an amphiphilic block copolymer poly(ethylene glycol)-poly[2-(methylacryloyl)ethylnicotinate] (PEG-PMAN) with aromatic nicotinate is used to load ZnPc for their π–π interactions. The formed PEG-PMAN/ZnPc nanoparticle (PPZ) dramatically increases reactive oxygen species production in osteosarcoma cells after light irradiation, causes mitochondrial injury and promotes cell cycle arrest at G2/M, leading to a 100-fold cytotoxicity improvement comparing with free ZnPc. The excellent therapeutic effectiveness and safety of PPZ are also proved by in vivo experiments operating on osteosarcoma model. The finding above indicates that PPZ has promising clinical applications as a next-generation photosensitizer in PDT of osteosarcoma.     

Enhanced photodynamic efficacy towards melanoma cells by encapsulation of Pc4 in silica nanoparticles

Nanoparticles have been explored recently as an efficient means of delivering photosensitizers for cancer diagnosis and photodynamic therapy (PDT). Silicon phthalocyanine 4 (Pc4) is currently being clinically tested as a photosensitizer for PDT. Unfortunately, Pc4 aggregates in aqueous solutions, which dramatically reduces its PDT efficacy and therefore limits its clinical application. We have encapsulated Pc4 using silica nanoparticles (Pc4SNP), which not only improved the aqueous solubility, stability, and delivery of the photodynamic drug but also increased its photodynamic efficacy compared to free Pc4 molecules. Pc4SNP generated photo-induced singlet oxygen more efficiently than free Pc4 as measured by chemical probe and EPR trapping techniques. Transmission electron microscopy and dynamic light scattering measurements showed that the size of the particles is in the range of 25–30 nm. Cell viability measurements demonstrated that Pc4SNP was more phototoxic to A375 or B16-F10 melanoma cells than free Pc4. Pc4SNP photodamaged melanoma cells primarily through apoptosis. Irradiation of A375 cells in the presence of Pc4SNP resulted in a significant increase in intracellular protein-derived peroxides, suggesting a Type II (singlet oxygen) mechanism for phototoxicity. More Pc4SNP than free Pc4 was localized in the mitochondria and lysosomes. Our results show that these stable, monodispersed silica nanoparticles may be an effective new formulation for Pc4 in its preclinical and clinical studies. We expect that modifying the surface of silicon nanoparticles encapsulating the photosensitizers with antibodies specific to melanoma cells will lead to even better early diagnosis and targeted treatment of melanoma in the future.     

Synthesis and in vitro photodynamic activities of pegylated distyryl boron dipyrromethene derivatives

A series of pegylated distyryl boron dipyrromethenes have been prepared and characterized. Their in vitro photodynamic activities in Tween 80 emulsions have also been investigated against HT29 human colorectal carcinoma cells. The derivative having five triethylene glycol chains (compound 8) exhibits the highest photocytotoxicity with an IC(50) as low as 7 nM. It is also localized preferentially in the endoplasmic reticulum of the cells and can induce predominately apoptosis upon illumination.     

Study of the stabilization of zinc phthalocyanine in sol-gel TiO2 for photodynamic therapy applications

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium dioxide (TiO₂) using the sol-gel method. It was prepared from stock solutions of ZnPc and TiO₂. ZnPc-TiO₂ was tested with four cancer cell lines. The characterization of supported ZnPc showed that phthalocyanine is linked by the N-pyrrole to the support and is stable up to 250°C, leading to testing for PDT. The preferential localization in target organelles such as mitochondria or lysosomes could determine the cell death mechanism after PDT. The results suggest that nanoparticulated TiO₂ sensitized with ZnPc is an excellent candidate as sensitizer in PDT against cancer and infectious diseases.From the Clinical EditorPhotodynamic therapy is a two-step procedure that uses a combination of molecular oxygen, visible light and photosensitizer agents as an alternative and promising non-invasive treatment for cancer. The results of this study suggest that nanoparticulated TiO₂ sensitized with ZnPc is an excellent photosensitizer candidate against cancer and infectious diseases.     

Novel Core-Interlayer-Shell DOX/ZnPc Co-loaded MSNs@ pH-Sensitive CaP@PEGylated Liposome for Enhanced Synergetic Chemo-Photodynamic Therapy

Purpose

This work was intended to develop novel doxorubicin (DOX)/zinc (II) phthalocyanine (ZnPc) co-loaded mesoporous silica (MSNs)@ calcium phosphate (CaP)@PEGylated liposome nanoparticles (NPs) that could efficiently achieve collaborative anticancer therapy by the combination of photodynamic therapy (PDT) and chemotherapy. The interlayer of CaP could be utilized to achieve pH-triggered controllable drug release, promote the cellular uptake, and induce cell apoptosis to further enhance the anticancer effects.

Methods

MSNs were first synthesized as core particles in which the pores were diffusion-filled with DOX, then the cores were coated by CaP followed by the liposome encapsulation with ZnPc to form the final DOX/ZnPc co-loaded MSNs@CaP@PEGylated liposome.

Results

A core-interlayer-shell MSNs@CaP@PEGylated liposomes was developed as a multifunctional theranostic nanoplatform. In vitro experiment indicated that CaP could not only achieve pH-triggered controllable drug release, promote the cellular uptake of the NPs, but also generate high osmotic pressure in the endo/lysosomes to induce cell apoptosis. Besides, the chemotherapy using DOX and PDT effect was achieved by the photosensitizer ZnPc. Furthermore, the MSNs@CaP@PEGylated liposomes showed outstanding tumor-targeting ability by enhanced permeability and retention (EPR) effect.

Conclusions

The novel prepared MSNs@CaP@PEGylated liposomes could serve as a promising multifunctional theranostic nanoplatform in anticancer treatment by synergic chemo-PDT and superior tumor-targeting ability.

     

Opposing functional effects of cyclic GMP and cyclic AMP may act through protein phosphorylation in rabbit cardiac myocytes

1. We tested the hypothesis that the negative functional effects of cyclic GMP (cGMP) oppose the positive effects of cyclic AMP (cAMP) in cardiac myocytes through interaction at the level of their respective protein kinases. 2. Cell shortening was studied using a video-edge detector. The O2 consumption of a suspension of rabbit ventricular myocytes was measured using O2 electrodes. Protein phosphorylation was measured autoradiographically following SDS-PAGE. Data were collected with: (1) 8-bromo-cGMP (8-Br-cGMP) 10(-7) or 10(-5) M; (2) 8-bromo-cAMP (8-Br-cAMP) 10(-7) or 10(-5) M; (3) 8-Br-cAMP 10(-5) M followed by 8-Br-cGMP 10(-7) or 10(-5) M; (4) 8-Br-cGMP 10(-5) M followed by 8-Br-cAMP 10(-7) or 10(-5) M; (5) 8-Br-cGMP 10(-7) or 10(-5) M followed by KT 5720 (cAMP-dependent protein kinase inhibitor) or KT 5823 (cGMP-dependent protein kinase inhibitor) 10(-6) M; and (6) 8-Br-cAMP 10(-7) or 10(-5) M followed by KT 5720 or KT 5823 10(-6) M. 3. 8-Br-cGMP 10(-5) M decreased percent shortening (Pcs) from 6.3+/-0.6 to 3.6+/-0.4% and rate of shortening (Rs) from 66.7+/-4.4 to 41.8+/-4.2 microm s(-1). 8-Br-cAMP 10(-5) M increased Pcs (from 3.7+/-0.2 to 4.8+/-0.2) and Rs (from 50.0+/-3.0 to 60.0+/-3.1). With 8-Br-cAMP 10(-5) M, 8-Br-cGMP 10(-5) M decreased Pcs and Rs less. The positive functional effects of 8-Br-cAMP 10(-7) or 10(-5) M were also diminished with 8-Br-cGMP 10(-5) M. Following 8-Br-cGMP 10(-7) or 10(-5) M, KT 5720 10(-6) M further decreased Pcs to 2.5+/-0.3 and Rs to 30.0+/-4.1. KT 5823 10(-6) M returned Pcs to 4.7+/-0.4 and Rs to 61.3+/-5.3. Following 8-Br-cAMP 10(-7) or 10(-5) M, KT 5720 decreased the elevated Pcs and Rs significantly and KT 5823 10(-6) M further increased these parameters. 4. cGMP and cAMP phosphorylated the same five protein bands. With KT 5720 or KT 5823, all of the bands were lighter at the same concentration of 8-Br-cAMP and 8-Br-cGMP. 5. We conclude that, in rabbit ventricular myocytes, the opposing functional effects of cGMP and cAMP are related to the interaction at the level of their respective protein kinases.     

Photophysicals and photochemicals studies of zinc(II) phthalocyanine in long time circulation micelles for photodynamic therapy use.

Long time circulation systems, such as polymeric micelles, represent a growing area in biomedical research. These microparticles can be used in many biological systems to provide appropriate drug levels with a specific biodistribution. Long time circulation micelles (LTCM) were routinely prepared using PEG-5000-DSPE (polyethyleneglycol-5000-distearoil-phosphatidyl-ethanolamine) and zinc(II) phthalocyanine (ZnPc) as a photosensitizer and fluorescent probe. This compound belongs to a second generation of photoactive agents, mainly used in photodynamic therapy (PDT) of neoplasic tissues. Their high selectivity for tumoral target tissues as well as high phototoxicity based on singlet oxygen generation renders the utilization of these compounds feasible as an alternative therapy for cancer treatment. LTCM were characterized by classical spectroscopic techniques. Absorbance measurements indicated that the drug was s completely loaded into LTCM (epsilon = 2.41 x 10(5) cm(-1)). This was also verified by steady state and time-resolved fluorescence measurements. The lifetime profiles of ZnPc decay curves were fitted according to biexponential function (tau1 = 3.9 ns and tau2 = 15.5 ns) indicating different locations for ZnPc into LTCM. The time-resolved spectroscopy measurements for ZnPc triplet excited state lifetimes (tauT) were calculated from the kinetic analysis of transient decays at the absorption maximum (480 nm), by using laser flash photolysis technique. All the spectroscopy measurements performed allowed us to conclude that, ZnPc in LTCM is a promising drug delivery system (DDS) for PDT.     

Enhanced photodynamic activity of meso-tetra(4-hydroxyphenyl)porphyrin by incorporation into sub-200 nm nanoparticles.

A photosensitizer, meso-tetra(hydroxyphenyl)porphyrin (p-THPP) was incorporated into sterile submicronic nanoparticles of poly(D,L-lactide-co-glycolide) (50:50 and 75:25 PLGA) and poly(D,L-lactide) (PLA). With all polymers used, sub-130 nm p-THPP-loaded nanoparticles with similar drug loadings and entrapment efficiencies were produced using the emulsification-diffusion technique. The photodynamic activity (photocytotoxicity) of these nanoparticles was evaluated on EMT-6 mammary tumour cells in comparison with the free drug. The influence of drug concentration (3-10 microg/ml), incubation time (5-60 min) and light dose (6-9 J/cm(2)) on p-THPP photocytotoxic efficiency was investigated. With all p-THPP formulations tested, cell viability decreased with increasing values of these parameters. The beneficial effect of nanoencapsulation compared to free drug was highlighted at drug concentrations up to 6 microg/ml and short incubation times (15-30 min). The most important photocytotoxicity was observed with 50:50 PLGA nanoparticles allowing low drug doses and short drug administration-irradiation intervals for local photodynamic therapy.     

Action spectrum of photoactivated phthalocyanine AIS2Pc in tumor bearing mice.

The action spectrum of disulfonated aluminum phthalocyanine (AIS2-Pc) as a photosensitizer for photodynamic therapy (PDT) was evaluated in vivo from 640 to 710 nm on two murine tumors with different biological properties. Mice bearing MS-2 fibrosarcoma and mice bearing the pigmented tumor B16 melanoma were injected with 5 mg/kg of AIS2Pc and irradiated with a light dose of 50 mW for 10 min for the MS-2 fibrosarcoma and of 100 mW for 10 min for the B16 melanoma. The action spectrum for both tumors presents a red shift with respect to the absorption spectrum of AIS2Pc in saline. The effectiveness is limited for short wavelengths (less than or equal to 655 nm for MS-2 and less than or equal to 660 for B16), whereas it increases at longer wavelengths and reaches its maximum at a peak (672 nm). For wavelengths beyond 672 nm the photodynamic activity remains up to 710 nm despite the significant decrease in absorption. The results obtained for both murine tumors seem therefore to indicate that an appreciable modification of the absorption spectrum takes place when AIS2Pc is incorporated into tissues following systematic administration.     

A Green-Absorbing,Red-Fluorescent Phenalenone-Based Photosensitizer as a Theranostic Agent for Photodynamic Therapy

Phenalenone is a synthetically accessible, highly efficient photosensitizer with a near-unity singlet oxygen quantum yield. Unfortunately, its UV absorption and lack of fluorescence has made it unsuitable for fluorescence-guided photodynamic therapy against cancer. In this work, we synthesized a series of phenalenone derivatives containing electron-donating groups to red-shift the absorption spectrum and bromine(s) to permit good singlet oxygen production via the heavy-atom effect. Of the derivatives synthesized, the phenalenone containing an amine at the 6-position with bromines at the 2- and 5-positions (OE19) exhibited the longest absorption wavelength (i.e., green) and produced both singlet oxygen and red fluorescence efficiently. OE19 induced photocytotoxicity with nanomolar potency in 2D cultured PANC-1 cancer cells as well as light-induced destruction of PANC-1 spheroids with minimal dark toxicity. Overall, OE19 opens up the possibility of employing phenalenone-based photosensitizers as theranostic agents for photodynamic cancer therapy.     

One-pot preparation of nanodispersion with readily available components for localized tumor photothermal and photodynamic therapy

Photothermal (PTT) and photodynamic (PDT) combined therapy has been hindered to clinical translation, due to the lack of available biomaterials, difficult designs of functions, and complex chemical synthetic or preparation procedures. To actualize a high-efficiency combination therapy for cancer via a feasible approach, three readily available materials are simply associated together in one-pot, namely the single-walled carbon nanohorns (SWCNH), zinc phthalocyanine (ZnPc), and surfactant TPGS. The established nanodispersion is recorded as PCT. The association of SWCNH/ZnPc/TPGS was confirmed by energy dispersive spectrum, Raman spectrum and thermogravimetric analysis. Under lighting, PCT induced a temperature rising up to about 60 °C due to the presence of SWCNH, production a 7-folds of singlet oxygen level elevation because of ZnPc, which destroyed almost all 4T1 tumor cells in vitro. The photothermal effect of PCT depended on both laser intensity and nanodispersion concentration in a linear and nonlinear manner, respectively. After a single peritumoral injection in mice and laser treatment, PCT exhibited the highest tumor temperature rise (to 65 °C) among all test groups, completely destroyed primary tumor without obvious toxicity, and inhibited distant site tumor. Generally, this study demonstrated the high potential of PCT nanodispersion in tumor combined therapy.     

Design,synthesis, characterization and in‐vivo activity of a novel salmon calcitonin conjugate containing a novel PEG‐lipid moiety

Objectives The aim of the study was to explore (1) the synthesis of a novel poly(ethylene glycol) modified lipid (PEG‐lipid, PL) containing a chemically active tri‐block linker, ε‐maleimido lysine (Mal), and its conjugation with salmon calcitonin (sCT), and (2) the biophysical properties and activity of the resulting conjugate, Mal‐PL‐sCT, relative to the control, 2PEG‐Mal‐sCT, which comprises sCT conjugated with α‐palmitoyl‐N‐ε‐maleimido‐l ‐lysine at cysteine 1 and cysteine 7, and PEG moieties at lysine 11 and lysine 18 via a conventional stepwise method. Methods The PEG‐lipid was obtained by condensing palmitic acid derivative of ε‐maleimido lysine with methoxy poly(ethylene glycol) amine. Under reductive conditions, the PEG‐lipid readily reacted with sCT to yield the resultant compound, Mal‐PL‐sCT. Key findings Dynamic light scattering analyses suggested that Mal‐PL‐sCT and 2PEG‐Mal‐sCT exhibited robust helical structures with a high tendency to aggregate in water. Both compounds were more stable against intestinal degradation than sCT, although Mal‐PL‐sCT was less stable than 2PEG‐Mal‐sCT. However, 2PEG‐Mal‐sCT did not possess hypocalcaemic activity while Mal‐PL‐sCT retained the hypocalcaemic activity of sCT when it was subcutaneously injected in the rat model. Multiple functional groups may be conjugated to a peptide via a tri‐block linker without the risk of obliterating the intrinsic bioactivity of the peptide. Conclusions The resultant novel PEG‐lipid has a potential role to optimize protein and peptide delivery.     

Thermosensitive PEG–PCL–PEG Hydrogel Controlled Drug Delivery System: Sol–Gel–Sol Transition and In Vitro Drug Release Study

In this article, biodegradable and low molecular weight poly(ethylene glycol)–poly(ε-caprolactone)–poly(ethylene glycol) (PEG–PCL–PEG, PECE) triblock copolymers were successfully synthesized. Aqueous solution of the obtained PECE copolymers underwent sol–gel–sol transition as temperature increased which was flowing sol at room temperature and then turned into nonflowing gel at body temperature. Sol–gel–sol phase transition behaviors of aqueous PECE solutions were studied using rheometry and test tube-inverting method, which were affected by many factors, including the heating/cooling procedure and different additives in copolymers aqueous solution. In vitro drug release behavior was studied using bovine serum albumin (BSA) and Vitamin B₁₂ (VB₁₂) as model drugs, and the PECE hydrogel could protect BSA from acidic degradation for 1 week at least. Therefore, PECE hydrogel is believed to be promising for injectable in situ gel-forming controlled drug delivery system due to their great thermosensitivity and biodegradability. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3707–3717, 2009