Polyoxometalates as a kind of molecular metal-oxide clusters with precise chemical composition and architecture have been demonstrated to show various potentials in multidisciplinary materials. Accompanying by their direct chemical interaction...
This work reports the ionic composition of a PEGylated and chemically crosslinked polyethyleneimine with a gadolinium‐coordinated polyoxomolybdate cluster, K17[Gd(P2Mo17O61)2], via electrostatic interaction. The prepared composites form nanoobjects with an average size of ≈27 nm at dried state and maintain structural stability in aqueous solution. While the biocompatibility on HeLa cells is demonstrated, the polymer‐shielded multifunctional nanoplatform shows both the combined magnetic resonance imaging and redox‐triggered photothermal conversion effect. As a contrast agent, the T1‐weighed relaxivity reaches up to 22.77 mm−1 s−1. The photothermal conversion of the prepared composites can be aroused by yielding a broad near infrared (NIR) adsorption through on‐site reduction of the glutathione that is enriched in the tumor environment. The high efficiency ≈61.0% under the irradiation of 808 nm NIR laser illustrates a distinct treatment capability according to cell counting Kit‐8 assay while the obvious inhibition for the growth of tumor cells is observed.
In the search for materials with enhanced near‐infrared (NIR) photothermal properties and capability of providing environment‐sensitive therapy, a method that combines isolated components into one nanocomposite is developed. The technique simultaneously involves redox, charge‐transfer formation, and ionic complexation. During the polyoxophosphomolybdate (PMo) cluster mixing with biosafe chromogen 3,3’,5,5’‐tetramethylbenzidine (TMB), the reduced state (rPMo) and the oxidized TMB in the state of charge‐transfer complex (cTMB) emerge spontaneously. The two reduced and oxidized components with charges form a stable ionic complex that resists physiology, saline, broad pH, and elevated temperature. Both the rPMo and cTMB contribute to the total sustainable photothermal conversion efficiency of 48.4% in the NIR‐II region. The ionic complex exhibits biocompatibility in in vitro cell viability evaluation and is demonstrated to enter tumor cells with sustained photothermal property and complexation stability. Due to the local acidity that triggers further interaction among rPMo clusters, a distinct accumulation of the ionic complex at the tumor position is observed after caudal vein injection. Moreover, a remarkable local NIR‐II photothermal image appears. The diminishment of tumor in mice with maintained body weight demonstrates the comprehensive effect of this NIR‐II photothermal therapeutic material.
To enhance the efficacy of tumor therapy, the collection
of functional
components into a targeting system shows advantages over most homogeneous
materials in inducing apoptosis of cancer cells. The security and
targeting of therapeutic agents also require the effect combination
of additional components. However, the construction of multifunctional
composites in a simple system with intelligent cooperative responsiveness
remains a challenge. Herein, a reduced polyanionic cluster (rP2W18) bearing the absorption at the near infrared
(NIR) II region is used as a core carrier to bind the positively charged
doxorubicin hydrochloride (DOX) through ionic interaction. To reduce
the physiological toxicity, hyaluronic acid grafting β-cyclodextrin
side chains is used to cover the ionic complex through host–guest
inclusion to DOX. When the nanocomposite is activated by local laser
exposure, the final three-component therapeutic agent is demonstrated
to present targeted photothermal conversion capability and chemodynamic
activity together with chemotherapy. With the controlled release of
DOX under the stimulation of mild acidity in the tumor region and
photothermal effect, the exposed rP2W18 is aroused
by hydrogen peroxide overexpressed in a tumor microenvironment to
produce toxic reactive oxygen species, 1O2.
This work presents an opportunity for the development of a nanocomposite
in NIR-II photothermal/chemo-therapy and chemodynamic synergistic
therapy.
Nanocomposites from the co-assemblies of block copolymers and a gadolinium-grafting inorganic cluster were constructed as a multifunctional platform for MRI enhancement, drug loading, and environment-response release at local positions.
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