Abstract
We report on a novel strategy for constructing graphene oxide nanomaterials with strongly enhanced photothermal (PT) and photoacoustic (PA) performance in the near-infrared (NIR)-II biowindow by chemical reduction. Optical spectra clearly reveal that obvious enhancement of optical absorption is observed in the whole NIR wideband from the NIR-I to NIR-II region for chemically reduced graphene oxide (CR-G) nanomaterials, which is mainly arising from the restoration of the electronic conjugation within the graphene oxide sheets and therefore inducing a black-body re-introduction effect of typical graphite-like materials. We experimentally synthesized CR-G samples with different degrees of reduction to demonstrate the efficiency of the proposed strategy. Experimental results show that the PT performance of the CR-G samples is greatly improved owing to the absorption enhancement by chemical reduction in the NIR-II biowindow. Furthermore, both in vitro and in vivo PA imaging of the CR-G samples with different degrees of reduction are performed to demonstrate their enhanced NIR-II PA performances. This work provides a feasible guidance for the rational design of graphene oxide nanomaterials with great potential for PT and PA applications in the NIR-II biowindow by chemical reduction.
Highlights
Carbon is one of the most common elements in our ecosystem [1,2]
Optical spectra clearly reveal that through chemical transformation, obvious enhancement of optical absorption is observed in the whole near infrared (NIR) wideband region for the chemically-reduced graphene oxide (CR-G) nanomaterials, which is mainly arising from the restoration of the electronic conjugation within the graphene oxide sheets and inducing a black-body re-introduction effect of typical graphite-like materials [20]
We reported a novel strategy for constructing graphene oxide nanomaterialsIn with strongly enhanced
Summary
Carbon is one of the most common elements in our ecosystem [1,2]. In the past decades, carbon-based nanomaterials have attracted large interests benefiting from their environmental and biological friendliness in both industrial and nanomedical applications [3,4,5].Among them, as a new member of the sp nanocarbon family, the stable, free-standing graphene oxide in a form of single-atom 2D flat sheet has shown unique physicochemical properties such as outstanding effective surface areas, easy of functionalization and wide-band optical absorption in near infrared (NIR) region, which enables unprecedented potential to support its adoption into next-generation biomedicine nanotechnologies [6,7,8,9].benefiting from its good photosensitizing and photothermal (PT) characteristics, significant progress has been made by using the ultrathin graphene oxide for PT and photoacoustic (PA) imaging, biosensing, and cancer therapies [10,11,12]. Rational design and proper engineering of graphene oxide with enhanced absorption are of great potential for their wide applications in the fields of biomedical imaging and phototherapy. Even though the NIR-II region has been proved to be a more competitive optical-window for bio-applications in deep-seated tissues, benefiting from the large allowable laser irradiation and less optical scattering [16,17], the previous works only focused on the absorption enhancement in the NIR-I (650–950 nm) region [18,19]. Developing strategy that can realize enhanced optical absorption enhancement in the NIR-II (980–1700 nm) region, and thereafter guarantee enhanced PA and PT applications in deep tissue is still of great significance
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