A Polyoxometalate Cluster Paradigm with Self-Adaptive Electronic Structure for Acidity/Reducibility-Specific Photothermal Conversion
Authors: Wenbo Bu
Chen Zhang
Linlin Zhang
Dalong Ni
Qing Li
Zheng Wang
Jianlin Shi
Chao Cheng
Changjing Zuo
Journal: Journal of the American Chemical Society (2016)
Discipline: CHEMISTRY
Keywords: Photothermal conversion; photothermal conversion materials; cancer photo-hyperthermia; Mo-based polyoxometalate cluster; intratumoral accumulation
Affiliations: State
Key Laboratory of High Performance Ceramics and Superfine Microstructure,
Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P.R. China, Shanghai
Key Laboratory of Green Chemistry and Chemical Processes, School of
Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, P.R. China, Department
of Nuclear Medicine, Changhai Hospital, Shanghai 200433, P.R. China

Abstract:  Photothermal conversion is one of the most important keys in the fields of solar collection, photo-hyperthermia, etc., and its performance is highly dependent on the photothermal conversion materials used. Especially in cancer photo-hyperthermia, the presently available small-molecule- or nanomaterial-based agents still suffer from numerous drawbacks, such as nonspecific accumulation and inevitable side effects on normal tissues. Here we identify a Mo-based polyoxometalate cluster that can change its dimension from small (1 nm) to big (tens of nanometer), favoring its intratumoral accumulation, and enhance photothermal conversion in response to the intratumoral acidity and reducibility, demonstrating a previously unrealized tumor-specific photo-hyperthermia. Distinct from the well-researched nano-based agents, a unique electronic structure of this cluster has been identified as the origin of the observed acidity-induced self-assembly and reduction-promoted NIR absorbance. In addition to providing a promising clinical agent, this finding is expected to establish a new physicochemical paradigm for photothermal materials design based on clusters. 

Retracted: No

PubPeer comments:
 The red and black lines seem to be identical at such a resolution. ![file] ![file] , 
 These two lines were recorded on the identical material at slightly different pHs, so they looks very similar with each other, BUT not identical with each other if detailedly checked. , 
 Could the athours provide high resolution figure or upload the raw date? , 
 Even the noises of these lines seem to be the same, especially in the left region, at such a low resolution. The authors should prvide a high resolution figure or upload the raw dates.![file] , 
 Dear all, the following are the two figures of high resolution (picture of size larger than 1 M is not allowed here, so the original pictures are still a little compressed) for your check. ![file] ![file] The indicated two lines are totally different in many details if you carefully check them even in the low-resolution version. By the way, you may easily understand why the left region (that is the low wave vector *k* region) in the oscillator functions look similar if you have little mathematical knowledge about the X-ray absorption fine structure. Firstly, the oscillator function is converted from the X-ray absorption spectrum of the material. The outer atoms will modulate the X-ray absorption of the center atom through multilevel electron scattering. This effect will induce the oscillation phenomenon observed in the X-ray absorption spectrum. Very different from the bulk materials, please note that the outer atom-shell is very limited for the extremely small POM cluster. Thus, the extent X-ray absorption characteristic for the individual POM cluster and the primarily-assembled hollow structure is nearly a straight line because the oscillating modulation effect is negligible here. Mathematically, the presented oscillator function is the similar straight line multiplied by the square of the wave vector in the low *k* region. So, the two lines in the left region should look similar. This is the essential reason for your doubt that why the left region looks similar and the right region looks different in the oscillation function. We are sorry the resolution of the picture is diminished (note this compression doesn t influence these discernable features in the picture) during the publishing process that causes your confusion. If you are further interested in this and think it is of necessity, we may provide the raw data of the X-ray absorption spectra. Hope these detailed explanations can well dispel your doubts. , 
 #5 Thanks for the author s patient answers. The pots are indeed different clearly shown in the high-resolution figure provided by the author. No more doubts. , 
 no more doubts but no need to say sorry? Just staying silent and leave? ,