Photothermal therapy (PTT) is recognized as a promising approach for cancer theranostics via the nonradiative conversion of light into heat energy. PTT treatment is able to reduce the adverse side effects of traditional chemotherapy. Some nanomaterials functionalized with unique physical and chemical properties have been integrated with multiple imaging modalities and a therapeutic function for applications. In the past decade, various nanomaterials for PTT applications have been reviewed, but a comprehensive survey of all classes of photothermal nanomaterials developed in recent years has not been done. A comprehensive discussion of PTT mechanisms using different nanomaterials and their application in combination therapy is useful for providing insights for PTT material development for disease treatment in the future. In this review, the recent advancement of functionalized nanomaterials for PTT and the excellence of PTT combined therapies in the field of anticancer are discussed. The momentous property of nanomaterials tailored for advancing the noninvasive therapeutic approach of PTT is also highlighted. Because a great deal of PTT nanomaterials have been developed in the past decades and reviewed in recent years, in this review, we only include the latest results reported in the past 5 years for discussion and comparison.

A series of π-conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE → NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (ΔG ∼ -1.1 and ΔG ∼ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE) remains approximately constant (λ ∼ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n ≤ 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1-10 ps time scale with the rates decreasing slightly with increased oligomer length (β ∼ 0.15 Å). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ∼ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers.

A new class of nonaggregating conjugated polyelectrolytes exhibits efficient fluorescence in aqueous solution. Analysis by optical spectroscopy and transmission electron microscopy reveals a unique structure−property correlation between oxygen substitution and aggregation.

A conjugated polyelectrolyte with symmetrically assembled hydrophilic and hydrophobic side groups along the backbone has been successfully synthesized and demonstrated significant photophysical tunability with 65 nm of wavelength shift and 10-fold of intensity enhancement for the emission maximum, through solvent composition adjustment. The highest fluorescence quenching effect (I/I 0 = 148) toward 10 μM of Fe 3þ was achieved in the solution having a THF/H 2 O ratio of 30/70, which could be attributed to a delicate balance among the influencing factors for the fluorescence quenching systems, the initial fluorescence, the rate of energy migration, and the accessibility of the receptors. The amplified symmetrical aggregation-nonaggregation inversion and the asymmetrical cation sensitivity across the whole range of H 2 O/THF composition were consistent with the molecular design.

We report on quadrupolar (donor)2-acceptor sensitizers for dye-sensitized solar cells (DSSCs). The acceptor units are based on dithieno[2,3-a:3',2'-c]phenazine and dithieno[3,2-a:2',3'-c]phenazine coupled to thiophene donors. The optoelectronic and photophysical properties of two sets of isomers reveal a rigid structure for linear isomers and an efficient nonradiative decay for branched isomers. These sensitizers were integrated into DSSCs, and the quadrupolar structure is an operational design, as the IPCE reached up to 38% from 400 nm to 600 nm. The lengthening of the donor chain increases the efficiency, demonstrating the appeal of these oligomeric dyes for DSSCs.