Illustration of the fluorescence "On" process. Credit: WANG Yanfang et al.

Photothermal therapy (PTT) is a promising alternative method for cancer treatment due to advantages of non-invasiveness, precise temporal and spatial control, strong specificity and high tumor destruction efficiency.

At present, the clinical evaluation of cancer treatment mainly relies on cytology, histopathology and imaging. Meanwhile, tumor therapy and its therapeutic efficiency evaluation are conducted separately.

Recently, a research group led by Prof. Liang Gaolin from University of Science and Technology of China (USTC) of Chinese Academy of Science, collaborating with Dr. Wang Longsheng from the Second Affiliated Hospital of Anhui Medical University, reported an 'intelligent' strategy of using organic nanoparticles to evaluate PTT efficiency on tumor in real time.

The study was published online in ACS Nano on July 27.

Via a CBT-Cys click condensation reaction, the researchers designed a small molecular near-infrared probe Cys(StBu)-Asp-Glu-Val-Asp-Lys(Cypate)-CBT (Cy-CBT) and prepared an intelligent nanoparticle Cy-CBT-NP, which is a fluorescence-quenched photothermal nanoparticle.

After tumor cells' uptake of Cy-CBT-NP, the tumor was treated with photothermal therapy under 808 nm laser irradiation. During the PTT, the tumor cell eventually died and the Caspase 3 (Casp 3) was activated.

Casp 3 specifically recognized and cleaved DEVD substrates in the Cy-CBT-NP to yield Cy-CBT-NP-Cleaved which was accompanied by near-infrared fluorescence (NIF), turning the fluorescence 'on.'

Because the PTT efficiency, Casp3 activity, and the turned-on NIR fluorescence intensity are positively correlated, this intelligent nanoparticle Cy-CBT-NP can be used to evaluate the tumor photothermal efficiency in real time.

Compared with the traditional tumor efficiency evaluation method, the strategy is real-time and can help doctors adjust the treatment plan in time.

How to make non-magnetic materials magnetic

A complex process can modify non-magnetic oxide materials in such a way to make them magnetic. The basis for this new phenomenon is controlled layer-by-layer growth of each material. An international research team with researchers from Martin Luther University Halle-Wittenberg (MLU) reported on their unexpected findings in the journal Nature Communications.

In solid-state physics, oxide layers only a few nanometres thick are known to form a so-called two-dimensional electron gas. These thin layers, separated from one another, are transparent and electrically insulating materials. However, when one thin layer grows on top of the other, a conductive area forms under certain conditions at the interface, which has a metallic shine. "Normally this system remains non-magnetic," says Professor Ingrid Mertig from the Institute of Physics at MLU. The research team has succeeded in controlling conditions during layer growth so that vacancies are created in the atomic layers near the interface. These are later filled in by other atoms from adjoining atomic layers.

The theoretical calculations and explanations for this newly discovered phenomenon were made by Ingrid Mertig's team of physicists. The method was then experimentally tested by several research groups throughout Europe—including a group led by Professor Kathrin Dörr from MLU. They were able to prove the magnetism in the materials. "This combination of computer simulations and experiments enabled us to decipher the complex mechanism responsible for the development of magnetism," explains Mertig.