Exploring the Potential of Gold Nanoparticles in Proton Therapy: Mechanisms, Advances, and Clinical Horizons

Proton therapy represents a groundbreaking advancement in cancer radiotherapy, leveraging the unique spatial energy distribution of protons to deliver precise, high-dose radiation to tumors while sparing surrounding healthy tissues. Despite its clinical success, proton therapy faces challenges in optimizing its therapeutic precision and efficacy. Recent research has highlighted the potential of gold nanoparticles to enhance proton therapy outcomes. Due to their high atomic number and favorable biological properties, gold nanoparticles act as radiosensitizers by amplifying the generation of secondary electrons and reactive oxygen species upon proton irradiation. This enhances DNA damage in tumor cells while preserving healthy tissues. Additionally, functionalization of gold nanoparticles with tumor-targeting ligands offers improved precision, making proton therapy more effective against a broader range of cancers. This review synthesizes current knowledge on the mechanisms of gold nanoparticle radiosensitization, preclinical evidence, and the technological hurdles that must be addressed to integrate this promising approach into clinical practice, aiming to advance the efficacy and accessibility of proton therapy in cancer therapy.

Sonodynamic and Acoustically Responsive Nanodrug Delivery System: Cancer Application

The advent of acoustically responsive nanodrugs that are specifically optimized for sonodynamic therapy (SDT) is a novel approach for clinical applications. Examining the therapeutic applications of sono-responsive drug delivery systems, understanding their dynamic response to acoustic stimuli, and their crucial role in enhancing targeted drug delivery are intriguing issues for current cancer treatment. Specifically, the suggested review covers SDT, a modality that enhances the cytotoxic activity of specific compounds (sonosensitizers) using ultrasound (US). Notably, SDT offers significant advantages in cancer treatment by utilizing US energy to precisely target and activate sonosensitizers toward deep-seated malignant sites. The potential mechanisms underlying SDT involve the generation of radicals from sonosensitizers, physical disruption of cell membranes, and enhanced drug transport into cells via US-assisted sonoporation. In particular, SDT is emerging as a promising modality for noninvasive, site-directed elimination of solid tumors. Given the complexity and diversity of tumors, many studies have explored the integration of SDT with other treatments to enhance the overall efficacy. This trend has paved the way for SDT-based multimodal synergistic cancer therapies, including sonophototherapy, sonoimmunotherapy, and sonochemotherapy. Representative studies of these multimodal approaches are comprehensively presented, with a detailed discussion of their underlying mechanisms. Additionally, the application of audible sound waves in biological systems is explored, highlighting their potential to influence cellular processes and enhance therapeutic outcomes. Audible sound waves can modulate enzyme activities and affect cell behavior, providing novel avenues for the use of sound-based techniques in medical applications. This review highlights the current challenges and prospects in the development of SDT-based nanomedicines in this rapidly evolving research field. The anticipated growth of this SDT-based therapeutic approach promises to significantly improve the precision of cancer treatment.

(Nano)biotechnological approaches in the treatment of cervical cancer: integration of engineering and biology

Cervical cancer is one of the most malignant gynaecological tumors characterised with the aggressive behaviour of the tumor cells. In spite of the development of different strategies for the treatment of cervical cancer, the tumor cells have developed resistance to conventional therapeutics. On the other hand, nanoparticles have been recently applied for the treatment of human cancers through delivery of drugs and facilitate tumor suppression. The stimuli-sensitive nanostructures can improve the release of therapeutics at the tumor site. In the present review, the nanostructures for the treatment of cervical cancer are discussed. Nanostructures can deliver both chemotherapy drugs and natural compounds to increase anti-cancer activity and prevent drug resistance in cervical tumor. Moreover, the genetic tools such as siRNA can be delivered by nanoparticles to enhance their accumulation at tumor site. In order to enhance selectivity, the stimuli-responsive nanoparticles such as pH- and redox-responsive nanocarriers have been developed to suppress cervical tumor. Moreover, nanoparticles can induce photo-thermal and photodynamic therapy to accelerate cell death in cervical tumor. In addition, nanobiotechnology demonstrates tremendous potential in the treatment of cervical cancer, especially in the context of tumor immunotherapy. Overall, metal-, carbon-, lipid- and polymer-based nanostructures have been utilized in cervical cancer therapy. Finally, hydrogels have been developed as novel kinds of carriers to encapsulate therapeutics and improve anti-cancer activity.

Evaluation of ALA-capped silver, copper, and silver-copper nanoparticles for controlling fungal plant pathogens

Phytopathogenic fungi significantly threaten global food security, causing substantial yield and quality losses. Sustainable solutions are urgently needed to combat these agricultural pathogens. This study explored the potential of silver (Ag), copper (Cu), and combined Ag/Cu nanoparticles capped with aminolevulinic acid (ALA) as antifungal agents. The nanoparticles (ALAAg, ALACu, and ALAAgCu) were synthesized via photoreduction and characterized using various techniques (UV-Vis, TEM, XRD, Zeta potential). Their antifungal activity against four key plant pathogens (Alternaria grandis, Colletotrichum truncatum, Corynespora cassiicola, and Fusarium oxysporum) was evaluated using poisoned food techniques. Notably, ALAAgCuNPs demonstrated superior antifungal activity compared to a conventional fungicide against two fungal strains. Even at lower concentrations, ALAAgCuNPs exhibited fungistatic effects comparable to those of the control. These promising results suggest the potential of ALAAgCu NPs as a broad-spectrum, potentially eco-friendly alternative for fungal control in plants and seeds. This approach is crucial for ensuring crop health, harvest quality, and food safety.

Synthesis, characterization, antimicrobial activity, and toxicity evaluation of aminolevulinic acid-silver and silver-iron nanoparticles for potential applications in agriculture

Aminolevulinic acid (ALA) is considered one of the most critical plants growth regulators and essential precursors for chlorophyll biosynthesis; besides, its photodynamic activity can be used to exterminate larvae and microorganisms in plants and soil. Silver nanoparticles (AgNPs) have unique physicochemical properties and potent antimicrobial, antiviral, and antifungal activities, and in agriculture, their application as nanopesticides has been proposed. In this study, silver and silver–iron nanoparticles capped/stabilized with aminolevulinic acid (ALAAgNPs and ALAAgFeNPs) were synthesized by the photoreduction method and characterized by UV-vis spectroscopy, transmission electron microscopy, and zeta potential analysis. The kinetics of ¹O₂ generation from ALAAgFeNPs were obtained. The ALANP toxicity was evaluated on stalks of E. densa by observing cell morphology changes and measuring chlorophyll content compared with water-treated plants. Antimicrobial activity was tested against E. coli, P. aeruginosa, and Candida albicans. The results suggested that ALANPs (prepared with [AgNO₃] ≤ 0.2 mM and [ALA] ≤ 0.4 mM) could be suitable for applications in the agricultural sector. The presence of ∼0.3 mmol of iron in ALAAgNPs synthesis increased cell uptake and chlorophyll synthesis.

ALA is a natural metabolite in all living cells and possesses low toxicity. ALANPs exhibit high antimicrobial activity, promote plant growth and have the potential to show photodynamic herbicidal properties under solar illumination.

Update on the Use of Nanocarriers and Drug Delivery Systems and Future Directions in Cervical Cancer

Cervical cancer represents a major health problem among females due to its increased mortality rate. The conventional therapies are very aggressive and unsatisfactory when it comes to survival rate, especially in terminal stages, which requires the development of new treatment alternatives. With the use of nanotechnology, various chemotherapeutic drugs can be transported via nanocarriers directly to cervical cancerous cells, thus skipping the hepatic first-pass effect and decreasing the rate of chemotherapy side effects. This review comprises various drug delivery systems that were applied in cervical cancer, such as lipid-based nanocarriers, polymeric and dendrimeric nanoparticles, carbon-based nanoparticles, metallic nanoparticles, inorganic nanoparticles, micellar nanocarriers, and protein and polysaccharide nanoparticles. Nanoparticles have a great therapeutic potential by increasing the pharmacological activity, drug solubility, and bioavailability. Through their mechanisms, they highly increase the toxicity in the targeted cervical tumor cells or tissues by linking to specific ligands. In addition, a nondifferentiable model is proposed through holographic implementation in the dynamics of drug delivery dynamics. As any hologram functions as a deep learning process, the artificial intelligence can be proposed as a new analyzing method in cervical cancer.

Chlorin e6-EGF conjugated gold nanoparticles as a nanomedicine based therapeutic agent for triple negative breast cancer

To develop a treatment modality for triple-negative breast cancer, we investigated the efficacy of a bifunctional theranostic nanoprobes (BN) during Photodynamic Therapy (PDT) on human breast carcinoma and normal human cells. The BN is a 21 nm gold nanoparticles functionalized with Chlorin e6 (Ce6) and Epidermal Growth Factor (EGF). Attachment to gold nanoparticle stabilizes Ce6 while EGF acts as a cancer cell targeting agent. Fluorescence Spectroscopy and Confocal Fluorescence Microscopy revealed a gradual uptake of nanoprobes into cancer cells at an average rate of 63 BN/min. Cell viability assays showed that 0.2 μg/mL BN concentration was highly cytotoxic to cancer cells (86 %), but not normal cells. At this concentration, 58 % cancer cells were necrotic and 38 % apoptotic, while the reactive oxygen species (ROS) was 9-fold higher in cancer cells compared to normal. Overall, results suggest that BN mediated PDT can achieve targeted cancer cell death with high efficiency.

Biocompatibility studies of intravenously administered ionic-crosslinked chitosan-BSA nanoparticles as vehicles for antitumour drugs

In this study, a new alternative of ionic crosslinked nanoparticles (NPs) based on chitosan (C) and bovine serum albumin (A; BSA) was evaluated as drug delivery system for antitumour compounds (doxorubicin hydrochloride as a model). The different responses to the pH of the medium were determined by the electrostatic interactions induced by each polymeric combination (C50/A50; C80/A20; C20/A80). NPs revealed a nanoscale size (167-392 nm) and a positive net charge (12-26 mV), modulated by doxorubicin (DOX) loading. Drug loading capacity was higher than 5.2 ± 1.8 μgDOX/mgNP (Encapsulation efficiency = 34%), and an initial burst release was followed by a sustained delivery. Cellular uptake assays confirmed the entry of NPs in three human tumor cells (MCF7, T47D and Hela), triggering antioxidant responses (superoxide dismutase, catalase, glutathione reductase and total glutathione content) in those cells. This was also consistent with the decreased in IC50 values observed after the incubation of these cells with C20/A80-DOX and C50/A50-DOX NPs (1.90-3.48 μg/mL) compared with free DOX (2.36-6.025 μg/mL). In vivo results suggested that the selected proportions of chitosan-BSA created nonhemolytic and biocompatible stable NPs at the selected dose of 20 mg/kg. Despite the different formulations, this study demonstrated that these NPs could serve as safe drug carriers in further in vivo investigations.

Study of THP-1 Macrophage Viability after Sonodynamic Therapy Using Methyl Ester of 5-Aminolevulinic Acid Gold Nanoparticles

Sonodynamic therapy (SDT) is emerging as new atherosclerosis treatment. The use of gold nanoparticles (AuNPs) as the vehicle for a sensitizer delivery improves reactive oxygen species formation. In this study, methyl ester of aminolevulinic acid (MALA) gold nanoparticles (MALA:AuNPs) functionalized with polyethylene glycol (PEG) were synthesized by photoreduction and characterized by ultraviolet/visible optical absorption, zeta potential and electron microscopy. The reactive oxygen species generation induced by ultrasound irradiation of MALA:AuNPs solutions was studied by observing the decrease in the 1,3-diphenylisobenzofuran emission band. The potential use of MALA:AuNPs as sensitizer for sonodynamic therapy was investigated on THP-1 macrophages. The cytotoxicity test was also described. The findings suggested that ultrasound combined with MALA:AuNPs provides impressive results in in vitro studies. Sonodynamic therapy with MALA:AuNPs through 2 minutes of ultrasound exposure (1 MHz and 1 W/cm2) culminated with total macrophage reduction. Thus, sonodynamic therapy combined with MALA:AuNPs has potential as a treatment for atherosclerosis.

Photodynamic therapy in 3D cancer models and the utilisation of nanodelivery systems

Photodynamic therapy (PDT) is the subject of considerable research in experimental cancer models mainly for the treatment of solid cancerous tumours. Recent studies on the use of nanoparticles as photosensitiser carriers have demonstrated improved PDT efficacy in experimental cancer therapy. Experiments typically employ conventional monolayer cell culture but there is increasing interest in testing PDT using three dimensional (3D) cancer models. 3D cancer models can better mimic in vivo models than 2D cultures by for example enabling cancer cell interactions with a surrounding extracellular matrix which should enable the treatment to be optimised prior to in vivo studies. The aim of this review is to discuss recent research using PDT in different types of 3D cancer models, from spheroids to nano-fibrous scaffolds, using a range of photosensitisers on their own or incorporated in nanoparticles and nanodelivery systems.

In vitro assessment of anti-tumorigenic mechanisms and efficacy of NanoALA, a nanoformulation of aminolevulic acid designed for photodynamic therapy of cancer

BACKGROUND

The development of nanocarriers is an important approach to increase the bioavailability of hydrophilic drugs in target cells. In this work, we evaluated the anti-tumorigenic mechanisms and efficacy of NanoALA, a novel nanoformulation of aminolevulic acid (ALA) based on poly(lactide-co-glycolide) (PLGA) nanocapsules designed for anticancer photodynamic therapy (PDT).

METHODS

For this purpose, physicochemical characterization, prodrug incorporation kinetics, biocompatibility and photocytotoxicity tests, analysis of the cell death type and mitochondrial function, measurement of the intracellular reactive oxygen species production and DNA fragmentation were performed in murine mammary carcinoma (4T1) cells.

RESULTS

NanoALA formulation, stable over a period of 90days following synthesis, presented hydrodynamic diameter of 220±8.7nm, zeta potential of -30.6mV and low value of polydispersity index (0.28). The biological assays indicated that the nanostructured product promotes greater ALA uptake by 4T1 cells and consequently more cytotoxicity in the PDT process. For the first time in the scientific literature, there is a therapeutic efficacy report of approximately 80%, after only 1h of incubation with 100μgmL^-1 prodrug (0.6mM ALA equivalent). The mitochondria are probably the initial target of treatment, culminating in energy metabolism disorders and cell death by apoptosis.

CONCLUSIONS

NanoALA emerges as a promising strategy for anticancer PDT. Besides being effective against a highly aggressive tumor cell line, the treatment may be economically advantageous because it allows a reduction in the dose and frequency of application compared to free ALA.

Design and Proof of Programmed 5-Aminolevulinic Acid Prodrug Nanocarriers for Targeted Photodynamic Cancer Therapy

5-Aminolevulinic acid (ALA), the precursor of photosensitizer protoporphyrin IX (PpIX), is a U.S. FDA-approved photodynamic therapeutic agent. However, realizing efficient delivery of ALA is still a big challenge as it is hydrophilic and cannot be recognized and selectively accumulated in tumor cells. In this study, matrix metalloproteinase-2 (MMP-2) and pH dual-sensitive ALA prodrug nanocarriers were constructed as a programmed delivery strategy for the targeted delivery of ALA. The nanocarriers were prepared by the co-modification of gold nanoparticles (AuNPs) with hydrazone-linked ALA and MMP-2-activatable cell-penetrating peptides (CPPs). Cationic CPP RRRRRRRR (R8) was shielded by zwitterionic stealth peptide EKEKEKEKEKEKEKEKEKEK (EK10) via MMP-2 substrate peptide PLGLAG. The zwitterionic stealth peptide EK10 is designed to endow ALA prodrug nanocarriers with strong antifouling ability and prolonged circulation time. Upon arriving at the tumor tissue, the shielded cationic CPP R8 can be activated by tumor-microenvironment-overexpressed MMP-2, which enabled enhanced cellular uptake of ALA. The results of drug loading and release, cellular uptake, PpIX generation and accumulation, photodynamic cytotoxicity, and photodynamic tumor inhibition demonstrated that such tumor-microenvironment-sensitive ALA prodrug nanocarriers could be considered as potential candidates for targeted photodynamic cancer therapy.

Current Advances in 5-Aminolevulinic Acid Mediated Photodynamic Therapy

Kennedy and Pottier discovered that photodynamic therapy (PDT) could be carried out using a procedure consisting of topical application of the porphyrin-precursor, 5-aminolevulinic acid (ALA) to the skin, followed after some time by illumination with various light parameters in the 1980s. Since then, ALA-PDT has expanded enormously and now covers most aspects of dermatological disease. The purpose of this review is to discuss a range of ingenious strategies that investigators have devised for improving the overall outcome (higher efficiency and lower side effects) of ALA-PDT. The big advance of using ALA esters instead of the free acid to improve skin penetration was conceived in the 1990s. A variety of more recent innovative approaches can be divided into three broad groups: (a) those relying on improving delivery or penetration of ALA into the skin; (b) those relying on ways to increase the synthesis of protoporphyrin IX inside the skin; (c) those relying on modification of the illumination parameters. In the first group, we have improved delivery of ALA with penetration-enhancing chemicals, iontophoresis, intracutaneous injection, or fractionated laser. There is also a large group of nanotechnology-related approaches with ALA being delivered using liposomes/ethosomes, ALA dendrimers, niosomes, mesoporous silica nanoparticles, conjugated gold nanoparticles, polymer nanoparticles, fullerene nanoparticles, and carbon nanotubes. In the second group, we can find the use of cellular differentiating agents, the use of iron chelators, and the effect of increasing the temperature. In the third group, we find methods designed to reduce pain as well as improve efficiency including fractionated light, daylight PDT, and wearable light sources for ambulatory PDT. This active area of research is expected to continue to provide a range of intriguing possibilities.

Intracellular Dual Fluorescent Lightup Bioprobes for Image-Guided Photodynamic Cancer Therapy

An intracellular dual fluorescent light-up bioprobe with aggregation-induced emission features and endogenously producing photosensitizer protoporphyrin IX (PpIX) abilities is designed and synthesized. The bioprobe is nonemissive in physiological environment. However, the bioprobe can selectively light up cancer cells with blue fluorescence of tetraphenylene (TPE) and red fluorescence of PpIX, owing to the release of TPE and methyl aminolevulinate after targeted internalization by cancer cells. Moreover, upon endogenous generation and accumulation of PpIX in cancer cells, efficient photodynamic ablation of cancer cells after light irradiation is demonstrated with easy regulation for optimal therapeutic efficacy. The design of such dual fluorescent light-up bioprobes might provide a new opportunity for targeted and image-guided photodynamic cancer therapy.

Chemistry for oncotheranostic gold nanoparticles

This review presents in a comprehensive ways the chemical methods used to functionalize gold nanoparticles with focus on anti-cancer applications. The review covers the parameters required for the synthesis gold nanoparticles with defined shapes and sizes, method for targeted delivery in tumours, and selected examples of anti-cancers compounds delivered with gold nanoparticles. A short survey of bioassays for oncology based on gold nanoparticles is also presented.

Aminolevulinic acid with gold nanoparticles: a novel theranostic agent for atherosclerosis

5-Aminolevulinic acid gold nanoparticles functionalized with polyethylene glycol were synthesized and administered to rabbits to evaluate their use in clinical practice as theranostic agents for atherosclerosis.

Anticancer efficacy of photodynamic therapy with hematoporphyrin-modified, doxorubicin-loaded nanoparticles in liver cancer

Photodynamic therapy (PDT) in combination with chemotherapy has great potential for cancer treatment. However, there have been very few attempts to developing cancer-targeted co-delivered systems of photosensitizers and anticancer drugs. We developed hematoporphyrin (HP)-modified doxorubicin (DOX)-loaded nanoparticles (HP-NPs) to improve the therapeutic effect of PDT in treating liver cancer. HP is not only a ligand for low density lipoprotein (LDL) receptors on the hepatoma cells but also a well-known photosensitizer for PDT. In vitro phototoxicity in HepG2 (human hepatocellular carcinoma) cells and in vivo anticancer efficacy in HepG2 tumor-bearing mice of free HP and HP-NPs were evaluated. The in vitro phototoxicity in HepG2 cells determined by MTT assay, annexin V-FITC staining and FACS analysis was enhanced in HP-NPs compared with free HP. Furthermore, compared with free HP-based PDT, in vivo anticancer efficacy in HepG2 tumor-bearing mice was markedly improved by HP-NPs-based PDT. Moreover, in both cases, the therapeutic effect was increased according to the irradiation time and number of PDT sessions. In conclusion, the HP-NPs prepared in this study represent a potentially effective co-delivery system of photosensitizer (HP) and anticancer drug (DOX) which improved the effects of PDT in liver cancer.