Limits...
Selective recognition of anionic cell membranes using targeted liposomes coated with zinc(ii)-bis(dipicolylamine) affinity units.

Turkyilmaz S, Rice DR, Palumbo R, Smith BD - Org. Biomol. Chem. (2014)

Bottom Line: One conjugate (Zn2BDPA-PEG2000-DSPE) was used in liposome formulations doped with the lipophilic near-infrared fluorophore DiR.Fluorescence cell microscopy studies demonstrated that the multivalent liposomes selectively and efficiently target bacteria in the presence of healthy mammalian cells and cause bacterial cell agglutination.The liposomes also exhibited selective staining of the surfaces of dead or dying human cancer cells that had been treated with a chemotherapeutic agent.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Biochemistry, 236 Nieuwland Science Hall. and University of Notre Dame, Notre Dame, IN 46556, USA. smith.115@nd.edu.

ABSTRACT
Zinc(ii)-bis(dipicolylamine) (Zn2BDPA) coated liposomes are shown to have high recognition selectivity towards vesicle and cell membranes with anionic surfaces. Robust synthetic methods were developed to produce Zn2BDPA-PEG-lipid conjugates with varying PEG linker chain length. One conjugate (Zn2BDPA-PEG2000-DSPE) was used in liposome formulations doped with the lipophilic near-infrared fluorophore DiR. Fluorescence cell microscopy studies demonstrated that the multivalent liposomes selectively and efficiently target bacteria in the presence of healthy mammalian cells and cause bacterial cell agglutination. The liposomes also exhibited selective staining of the surfaces of dead or dying human cancer cells that had been treated with a chemotherapeutic agent.

Show MeSH

Related in: MedlinePlus

Preparation of BDPA-PEG2000-DSPE (7). Conditions: (i) PfpOH, EDC, DMAP, CHCl3, 0 °C to rt, 16 h followed by (ii) H2N-PEG2000-DSPE, DIPEA, CHCl3, rt, 24 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4128505&req=5

sch2: Preparation of BDPA-PEG2000-DSPE (7). Conditions: (i) PfpOH, EDC, DMAP, CHCl3, 0 °C to rt, 16 h followed by (ii) H2N-PEG2000-DSPE, DIPEA, CHCl3, rt, 24 h.

Mentions: With 6 in hand we turned our attention to the preparation of BDPA-PEG2000-DSPE (7). A multitude of methods can be considered for the amide bond formation between 6 and H2N-PEG2000-DSPE.46 We found that the EDC/DMAP mediated pentafluorophenol (PfpOH) activation of 6 followed by reaction with H2N-PEG2000-DSPE reliably afforded BDPA conjugate 7 (Scheme 2). Using this method it was possible to prepare tens of milligrams of 7 in one run and purification merely consisted of a relatively simple preparatory TLC procedure. It should be noted that commercially available H2N-PEG2000-DSPE is a polydisperse mixture of PEG chains with a mean degree of polymerization around 45 and this is reflected in the HRMS spectrum of 7 (ESI). To remove the mass spectral ambiguity regarding the identity of the product and to demonstrate the versatility of the synthetic methods we decided to prepare BDPA-PEG500-DSPE (10) from commercially available monodisperse FmocNH-PEG500-propionic acid (8). Reaction of PfpOH activated 8 with DSPE proved very sluggish in a wide variety of solvents due to the poor solubility of this phospholipid. This problem was overcome by refluxing the reaction. Removal of the Fmoc group using piperidine and reaction of the resulting H2N-PEG500-DSPE (9) with PfpOH activated 6 afforded the desired conjugate 10 in good yield (Scheme 3). It was possible to purify 10 using a relatively simple preparatory TLC procedure and the spectral data indicated monodispersity.


Selective recognition of anionic cell membranes using targeted liposomes coated with zinc(ii)-bis(dipicolylamine) affinity units.

Turkyilmaz S, Rice DR, Palumbo R, Smith BD - Org. Biomol. Chem. (2014)

Preparation of BDPA-PEG2000-DSPE (7). Conditions: (i) PfpOH, EDC, DMAP, CHCl3, 0 °C to rt, 16 h followed by (ii) H2N-PEG2000-DSPE, DIPEA, CHCl3, rt, 24 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128505&req=5

sch2: Preparation of BDPA-PEG2000-DSPE (7). Conditions: (i) PfpOH, EDC, DMAP, CHCl3, 0 °C to rt, 16 h followed by (ii) H2N-PEG2000-DSPE, DIPEA, CHCl3, rt, 24 h.
Mentions: With 6 in hand we turned our attention to the preparation of BDPA-PEG2000-DSPE (7). A multitude of methods can be considered for the amide bond formation between 6 and H2N-PEG2000-DSPE.46 We found that the EDC/DMAP mediated pentafluorophenol (PfpOH) activation of 6 followed by reaction with H2N-PEG2000-DSPE reliably afforded BDPA conjugate 7 (Scheme 2). Using this method it was possible to prepare tens of milligrams of 7 in one run and purification merely consisted of a relatively simple preparatory TLC procedure. It should be noted that commercially available H2N-PEG2000-DSPE is a polydisperse mixture of PEG chains with a mean degree of polymerization around 45 and this is reflected in the HRMS spectrum of 7 (ESI). To remove the mass spectral ambiguity regarding the identity of the product and to demonstrate the versatility of the synthetic methods we decided to prepare BDPA-PEG500-DSPE (10) from commercially available monodisperse FmocNH-PEG500-propionic acid (8). Reaction of PfpOH activated 8 with DSPE proved very sluggish in a wide variety of solvents due to the poor solubility of this phospholipid. This problem was overcome by refluxing the reaction. Removal of the Fmoc group using piperidine and reaction of the resulting H2N-PEG500-DSPE (9) with PfpOH activated 6 afforded the desired conjugate 10 in good yield (Scheme 3). It was possible to purify 10 using a relatively simple preparatory TLC procedure and the spectral data indicated monodispersity.

Bottom Line: One conjugate (Zn2BDPA-PEG2000-DSPE) was used in liposome formulations doped with the lipophilic near-infrared fluorophore DiR.Fluorescence cell microscopy studies demonstrated that the multivalent liposomes selectively and efficiently target bacteria in the presence of healthy mammalian cells and cause bacterial cell agglutination.The liposomes also exhibited selective staining of the surfaces of dead or dying human cancer cells that had been treated with a chemotherapeutic agent.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Biochemistry, 236 Nieuwland Science Hall. and University of Notre Dame, Notre Dame, IN 46556, USA. smith.115@nd.edu.

ABSTRACT
Zinc(ii)-bis(dipicolylamine) (Zn2BDPA) coated liposomes are shown to have high recognition selectivity towards vesicle and cell membranes with anionic surfaces. Robust synthetic methods were developed to produce Zn2BDPA-PEG-lipid conjugates with varying PEG linker chain length. One conjugate (Zn2BDPA-PEG2000-DSPE) was used in liposome formulations doped with the lipophilic near-infrared fluorophore DiR. Fluorescence cell microscopy studies demonstrated that the multivalent liposomes selectively and efficiently target bacteria in the presence of healthy mammalian cells and cause bacterial cell agglutination. The liposomes also exhibited selective staining of the surfaces of dead or dying human cancer cells that had been treated with a chemotherapeutic agent.

Show MeSH
Related in: MedlinePlus