1,721,063 research outputs found
Role of delivery vehicles for photosensitizers in the photodynamic therapy of tumours.
No full textThe use of photosensitizing drugs associated with different types of delivery vehicle has received strong interest within the field of the photodynamic therapy of tumours. Lipid-based delivery vehicles, such as liposomes and oil emulsions, allow the administration of water-insoluble photosensitizers, widening the choice of photosensitizers potentially useful for treating tumours. In some cases, these delivery vehicles increase the selectivity of tumour targeting by favouring photosensitizer uptake in tumour tissue. However, a higher selectivity of tumour targeting could be obtained through the association of photosensitizers with delivery vehicles which can interact preferentially or specifically with tumour cells. With this aim in mind, low-density lipoproteins (LDLs) and monoclonal antibodies, in particular, are regarded as the most promising delivery systems for anticancer drugs. Some pharmacokinetic studies with LDL-associated photosensitizers have demonstrated a higher tumour uptake compared with the same photosensitizers delivered with other formulations. Monoclonal antibody-coupled photosensitizers have been tested mainly in vitro, and have shown a high selectivity towards cells expressing specific antigens. Only a limited number of reports are available on the biodistribution of immunoconjugated photosensitizers and on their selectivity in vivo, so that their importance for the selectivity of tumour targeting has not yet been defined
Interaction of human serum albumin with hematoporphyrin and its Zn(2)+-and Fe(3)+-derivatives.
No full textConjugation of photosensitisers to antimicrobial peptides increases the efficiency of photodynamic therapy in cancer cells
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Photochemical and photosensitizing properties of monomeric and dimeric Sn(IV)-protoporphyrin
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Folate-targeted PEGylated liposomes improve the selectivity of PDT with meta-tetra(hydroxyphenyl)chlorin (m-THPC)
No full textThe folate receptor (FR) is over-expressed in many human tumours and is being intensively studied also
in the field of nanomedicine as a target to enhance the selectivity of drug delivery to cancer cells by
using nanocarriers bearing folic acid (FA) on their surface. In this study we report the encapsulation of
the photosensitizer (PS) meta-tetra(hydroxyphenyl)chlorin (m-THPC) in FA-targeted PEGylated liposomes
used as a novel drug delivery system for photodynamic therapy (PDT) of cancer. Our in vitro investigations
revealed that only a modest fraction of targeted liposomes were internalized by specific endocytosis in
FR-positive KB cells. However, FA-liposomes doubled the uptake of the entrapped m-THPC with respect
to un-targeted liposomes and enhanced the photo-induced cytotoxicity in KB cells. In contrast, in FRnegative
A549 cells FA-targeted or un-targeted liposomes exhibited a very similar extent of internalization
and as a consequence the same photo-killing efficiency
Strategies for optimizing the delivery to tumors of macrocyclic photosensitizers used in photodynamic therapy (PDT)
No full textThis review briefly summaries the principles and mechanisms of action of photodynamic therapy (PDT) as concerns its application in the oncological field, highlighting its drawbacks and some of the strategies that have been or are being explored to overcome them. The major aim is to increase the efficiency and selectivity of the photosensitizer (PS) uptake in the cancer cells for optimizing the PDT effects on tumors while sparing normal cells. Some attempts to achieve this are based on the conjugation of the PS to biomolecules (small ligands, peptides) functioning as carriers with the ability to efficiently penetrate cells and/or specifically recognize and bind proteins/receptors overexpressed on the surface of cancer cells. Alternatively, the PS can be entrapped in nanocarriers derived from various types of materials that can target the tumor by exploiting the enhanced permeability and retention (EPR) effects. The use of nanocarriers is particularly attractive because it allows the simultaneous delivery of more than one drug with the possibility of combining PDT with other therapeutic modalities.</jats:p
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