Investigation of the emission spectra and cytotoxicity of TiO2 and Ti-MSN/PpIX nanoparticles to induce photodynamic effects using X-ray

Nanomaterials for light-mediated therapeutics in deep tissue

Light-mediated therapeutics, including photodynamic therapy, photothermal therapy and light-triggered drug delivery, have been widely studied due to their high specificity and effective therapy. However, conventional light-mediated therapies usually depend on the activation of light-sensitive molecules with UV or visible light, which have poor penetration in biological tissues. Over the past decade, efforts have been made to engineer nanosystems that can generate luminescence through excitation with near-infrared (NIR) light, ultrasound or X-ray. Certain nanosystems can even carry out light-mediated therapy through chemiluminescence, eliminating the need for external activation. Compared to UV or visible light, these 4 excitation modes penetrate more deeply into biological tissues, triggering light-mediated therapy in deeper tissues. In this review, we systematically report the design and mechanisms of different luminescent nanosystems excited by the 4 excitation sources, methods to enhance the generated luminescence, and recent applications of such nanosystems in deep tissue light-mediated therapeutics.

Design of a novel nanoparticle to use X-ray fluorescence of TiO2 to induce photodynamic effects in the presence of PpIX

BACKGROUND

Radiotherapy and photodynamic therapy are the methods of cancer treatment. Although one limitation of photodynamic therapy (PDT) is the limited penetration depth of light through tissue, using X-rays does not have this restriction. Self-lighting nanoparticles can convert X-rays into UV/visible. This study focuses on a newly designed nanostructure containing mesoporous silica nanoparticles (MSN), titanium dioxide nanoparticles (TiO2, anatase grade), and protoporphyrin IX (PpIX) as a photosensitizer to overcome the limitations of photodynamic therapy.

METHODS

After the synthesis and characterization of Ti-MSN/PpIX@PVP nanostructure, two ROSes (OH* and 1O2) were measured when the nanostructures were irradiated with 100 kV and 6 MV photons. The toxicity of Ti-MSN/PpIX@PVP nanostructure in presence and absence of radiation was investigated on DFW and HT-29 cell lines. The in-vitro experiments were analyzed using the MTT assay and colony count assay. Finally, the effect of light exposure in the presence of Ti-MSN/PpIX@PVP nanostructure on the two cell lines was studied. The in-vitro studies were evaluated using the Synergism Index (Syn) and Dose Enhancement Factor (DEF).

RESULTS

Based on the FESEM (field emission scanning electron Microscopy) images and DLS (dynamic light scattering) measurements, the size of Ti-MSN/PpIX nanostructure was determined as (35.2 nm) and (168.4 nm), respectively. Based on the spectrofluorimetry results, 100 kV photons produced more ROSes than 6 MV photons. The results of MTT assay and colony formation for X-PDT show Syn >1, except for 100 kV photons for HT-29 cell line. The nanostructure also reduced colony formation induced by X-PDT more effectively when irradiated by 100 kV photons on DFW cells. The results obtained from conventional PDT showed that the ED 50 of the HT-29 cell line was 6 times higher than that of the DFW cell line.

CONCLUSION

Designing and synthesizing Ti-MSN/PpIX@PVP nanostructures offer a promising strategy for reducing the current challenges in PDT and for developing and advancing X-PDT as an innovative cancer treatment technique.

Influence of Critical Parameters on Cytotoxicity Induced by Mesoporous Silica Nanoparticles

Mesoporous Silica Nanoparticles (MSNs) have received increasing attention in biomedical applications due to their tuneable pore size, surface area, size, surface chemistry, and thermal stability. The biocompatibility of MSNs, although generally believed to be satisfactory, is unclear. Physicochemical properties of MSNs, such as diameter size, morphology, and surface charge, control their biological interactions and toxicity. Experimental conditions also play an essential role in influencing toxicological results. Therefore, the present study includes studies from the last five years to statistically analyse the effect of various physicochemical features on MSN-induced in-vitro cytotoxicity profiles. Due to non-normally distributed data and the presence of outliers, a Kruskal-Wallis H test was conducted on different physicochemical characteristics, including diameter sizes, zeta-potential measurements, and functionalisation of MSNs, based on the viability results, and statistical differences were obtained. Subsequently, pairwise comparisons were performed using Dunn's procedure with a Bonferroni correction for multiple comparisons. Other experimental parameters, such as type of cell line used, cell viability measurement assay, and incubation time, were also explored and analysed for statistically significant results.

Synthesis and photodynamic efficacy of water-soluble protoporphyrin IX homologue with mPEG550

Protoporphyrin IX (PpIX), which is an efficient photosensitive agent, cannot be used directly in photodynamic therapy due to its aggregation in physiological environment. If PpIX is made water-soluble without losing its photosensitive properties, it can be used in many medical fields, including cancer treatment. Here we report synthesis of PpIX homologue with mPEG550 (Porfipeg) and its photodynamic effects on both in-vitro and in-vivo environment. Porfipeg is synthesized to give PpIX the ability to dissolve in water. Spectrometric (FT-IR, NMR, MS, UV-vis and Fluorescence) measurements were performed. Porfipeg can penetrate into the cells and indicates no cytotoxicity in the dark whereas cell viability significantly reduced with light irradiation. The cells can be visualized by fluorescence microscope. In-vivo experiment revealed that intravenous injection of Porfipeg is more efficient than intraperitoneal injection for the acute photodynamic effects within 30 min. Moreover it is excreted by the kidneys. In conclusion, Porfipeg has remarkable potentials to be used in both fluorescence guidance in surgeries and photodynamic therapy for cancer treatment.

Advances of Nanomedicine in Radiotherapy

Radiotherapy (RT) remains one of the current main treatment strategies for many types of cancer. However, how to improve RT efficiency while reducing its side effects is still a large challenge to be overcome. Advancements in nanomedicine have provided many effective approaches for radiosensitization. Metal nanoparticles (NPs) such as platinum-based or hafnium-based NPs are proved to be ideal radiosensitizers because of their unique physicochemical properties and high X-ray absorption efficiency. With nanoparticles, such as liposomes, bovine serum albumin, and polymers, the radiosensitizing drugs can be promoted to reach the tumor sites, thereby enhancing anti-tumor responses. Nowadays, the combination of some NPs and RT have been applied to clinical treatment for many types of cancer, including breast cancer. Here, as well as reviewing recent studies on radiotherapy combined with inorganic, organic, and biomimetic nanomaterials for oncology, we analyzed the underlying mechanisms of NPs radiosensitization, which may contribute to exploring new directions for the clinical translation of nanoparticle-based radiosensitizers.

Which is Better for Nanomedicines: Nanocatalysts or Single-Atom Catalysts?

With the rapid advancements in nanotechnology and materials science, numerous nanomaterials have been used as catalysts for nanomedical applications. Their design and modification according to the microenvironment of diseases have been shown to achieve effective treatment. Chemists are in pursuit of nanocatalysts that are more efficient, controllable, and less toxic by developing innovative synthetic technologies and improving existing ones. Recently, single-atom catalysts (SACs) with excellent catalytic activity and high selectivity have attracted increasing attention because of their accurate design as nanomaterials at the atomic level, thereby highlighting their potential for nanomedical applications. In this review, the recent advances in nanocatalysts and SACs are briefly summarized according to their synthesis, characterizations, catalytic mechanisms, and nanomedical applications. The opportunities and future scope for their development and the issues and challenges for their application as nanomedicine are also discussed. As far as it is known, the review is the systematic comparison of nanocatalysts and SACs, especially in the field of nanomedicine, which has promoted the development of nanocatalytic medicine.

Progress in Mesoporous Silica Nanoparticles as Drug Delivery Agents for Cancer Treatment

Cancer treatment and therapy have made significant leaps and bounds in these past decades. However, there are still cases where surgical removal is impossible, metastases are challenging, and chemotherapy and radiotherapy pose severe side effects. Therefore, a need to find more effective and specific treatments still exists. One way is through the utilization of drug delivery agents (DDA) based on nanomaterials. In 2001, mesoporous silica nanoparticles (MSNs) were first used as DDA and have gained considerable attention in this field. The popularity of MSNs is due to their unique properties such as tunable particle and pore size, high surface area and pore volume, easy functionalization and surface modification, high stability and their capability to efficiently entrap cargo molecules. This review describes the latest advancement of MSNs as DDA for cancer treatment. We focus on the fabrication of MSNs, the challenges in DDA development and how MSNs address the problems through the development of smart DDA using MSNs. Besides that, MSNs have also been applied as a multifunctional DDA where they can serve in both the diagnostic and treatment of cancer. Overall, we argue MSNs provide a bright future for both the diagnosis and treatment of cancer.