At the core of this discovery lies the sophisticated manipulation of light-matter interactions at subwavelength scales facilitated by quasi-BIC metasurfaces. These metasurfaces operate by sustaining electromagnetic modes that reside at the cusp of the continuum spectrum, with radiation losses effectively suppressed by symmetry-breaking perturbations. Such engineering confers extraordinarily high optical quality (Q) factors, crucial for amplifying the local electromagnetic field and thereby dramatically enhancing photochemical processes. Singlet oxygen (^1O_2), a highly reactive oxygen species with pivotal roles in cell signaling, photodynamic therapy, and oxidative degradation, has historically presented challenges in generation and localization—a barrier now surmounted by these meta-architectures.

The research team meticulously designed two-dimensional arrays of resonators, each geometry sculpted to break inherent symmetries and thereby evoke quasi-BIC modes tunable across relevant photonic bands. By finely adjusting geometric asymmetry, they achieved an unprecedented balance where radiation leakage was minimized without sacrificing optical accessibility. This fine control of the resonance landscape enabled the generation of intense near-fields, which, when exposed to photosensitizer molecules or oxygen directly, facilitated the efficient excitation and transfer of energy to molecular oxygen, producing singlet oxygen at rates orders of magnitude higher than conventional methods.

Characterization of these metasurfaces incorporated advanced spectroscopic methods and microscopic reactive oxygen species mapping, revealing highly localized, rapid singlet oxygen generation within nanometric domains. Notably, the spatial confinement of these reactions was validated by employing chemical probes sensitive exclusively to singlet oxygen, underscoring the precise manipulation of photochemical reactivity without collateral photodamage to surrounding matrices. This degree of control paves the way for integrating such devices into biomedical implants or environmental sensors where ROS can be produced on demand with minimal invasiveness.

Beyond the purely photonic design, the study explored how material selection influences overall functionality. Utilization of high-refractive-index dielectric materials minimized intrinsic losses while supporting robust electric and magnetic dipolar resonances essential for BIC formation. Moreover, the spectral response of these metasurfaces could be tailored across the visible to near-infrared regimes, aligning with the absorption spectra of commonly used photosensitizers and expanding compatibility with diverse practical applications.

One of the most striking aspects of this technology is its speed and efficiency in singlet oxygen production. According to the reported data, the generation rates achieved via quasi-BIC metasurfaces outperformed traditional photosensitized reactions by several fold, substantially reducing the illumination intensity and exposure times necessary for effective outcomes. This acceleration may enable safer photodynamic therapies, where prolonged light exposure has previously limited applicability due to tissue heating or off-target effects.

The study further emphasizes the versatility of the quasi-BIC metasurfaces in modulating the temporal dynamics of singlet oxygen generation. By tuning resonator parameters and exploiting interference effects, the researchers could achieve pulsed or continuous ROS generation regimes, potentially enabling dynamic control in therapeutic or synthetic environments. Such adaptability is invaluable for tailored treatments or chemical processes demanding precise timing and dosage of reactive species.

Crucially, the environmental stability and reusability of these metasurfaces were demonstrated through repeated singlet oxygen generation cycles without significant degradation in performance. This robustness underscores the practicality of deploying quasi-BIC metasurfaces in real-world settings where durability and consistent functionality are paramount. Integrating these structures with microfluidic platforms or implantable devices could usher in a new era of responsive and maintenance-free photochemical reaction systems.

The implications of this work extend deeply into nanophotonics research, inspiring further exploration of quasi-BIC phenomena for catalysis, sensing, and energy conversion. The ability to concentrate electromagnetic energy into subwavelength volumes with high Q factors while maintaining accessibility through controlled symmetry-breaking opens avenues for numerous light-driven chemical transformations previously deemed inefficient or unmanageable.

From a medical perspective, the swift and localized singlet oxygen generation may revolutionize photodynamic therapy protocols, enhancing therapeutic efficacy against tumors, microbial infections, or pathological tissues while minimizing side effects. This is particularly impactful given the growing clinical demand for non-invasive, highly targeted treatments and the limitations of current photosensitizers constrained by diffusion and activation threshold issues.

Furthermore, the environmental applications are equally compelling. Singlet oxygen functions as a potent oxidant in the degradation of organic pollutants and pathogens. The ability to generate this species rapidly and locally on metasurfaces could leverage sunlight or artificial light sources for water purification, air quality enhancement, and sterilization processes with greater energy efficiency and reduced chemical waste.

By bridging fundamental photonics and applied chemistry, the research by Long and colleagues illuminates a pathway toward sustainable, highly controlled generation of reactive oxygen species. The findings encourage the pursuit of hybrid systems coupling these metasurfaces with novel photosensitizers and functional materials to harness synergistic effects, possibly unlocking performance levels unattainable by current technologies.

In conclusion, the advent of quasi-BIC metasurfaces marks a paradigm shift in controlling singlet oxygen chemistry via photonics. The ability to induce rapid, localized, and tunable reactive species production through engineered nanostructures sets a new benchmark for innovation at the intersection of light and matter. As this field accelerates, the prospective applications spanning medicine, environmental science, and energy conversion promise to capture global research and industrial interest, heralding a new chapter of precision photochemistry driven by the elegant physics of quasi-bound states in the continuum.

Subject of Research: Quasi-bound states in the continuum (quasi-BIC) metasurfaces for enhanced singlet oxygen generation.

Article Title: Quasi-BIC metasurfaces enable rapid, localized singlet-oxygen generation.

Article References:
Long, R., Lin, L., Qi, X. et al. Quasi-BIC metasurfaces enable rapid, localized singlet-oxygen generation. Light Sci Appl 15, 188 (2026). https://doi.org/10.1038/s41377-026-02267-9

Image Credits: AI Generated

DOI: 10.1038/s41377-026-02267-9

Keywords: Quasi-bound states in the continuum, metasurfaces, singlet oxygen, reactive oxygen species, photochemistry, photodynamic therapy, nanophotonics, optical resonators, high-Q factor, symmetry breaking, dielectric materials, localized light-matter interaction

Psoriasis pathophysiology presents significant barriers to effective treatment, primarily due to the thickened epidermis which severely limits transdermal drug delivery. Moreover, the hypoxic conditions prevalent in psoriatic lesions contribute to an inflammatory milieu that undermines the effectiveness of conventional therapies, including photodynamic therapy (PDT). The introduction of this dual-section microneedle (MN) patch, termed S-PTP MN patch, systematically addresses these obstacles by integrating oxygen generation capabilities and ROS-responsive drug release into a singular, patient-friendly device capable of penetrating deep into the affected dermal layers.

The needle section of the S-PTP MN patch is meticulously engineered with PTP nanoparticles loaded with the corticosteroid triamcinolone acetonide (TA), a cornerstone anti-inflammatory medication in dermatology. These particles are enveloped within a reactive oxygen species (ROS)-responsive layer, enabling the drug to be released precisely in the oxidative microenvironment characteristic of psoriatic lesions. This targeted, stimulus-responsive mechanism provides a controlled and sustained release of TA over six days, ensuring continuous therapeutic activity while minimizing systemic exposure and associated side effects.

Complementing the active drug delivery, the base section of the patch incorporates sodium percarbonate (SPC) particles, a strategic inclusion that serves as an oxygen generator. Upon application, the SPC particles react to release oxygen locally within the hypoxic microenvironment of the psoriatic skin. The resultant oxygenation not only facilitates deeper penetration of the PTP nanoparticles but also significantly enhances the efficacy of photodynamic therapy, which is inherently oxygen-dependent. This dual-action platform therefore optimizes both drug delivery and PDT in a synergistic manner.

An in-depth investigation utilizing an imiquimod-induced psoriatic mouse model demonstrated compelling therapeutic outcomes following a single application of the S-PTP MN patch. Compared to conventional topical TA cream, the microneedle patch achieved superior results in attenuating clinical symptoms of psoriasis. Quantitative analyses revealed marked reductions in epidermal thickness and a pronounced decrease in pro-inflammatory cytokine expression, underscoring the patch’s potent anti-inflammatory effect and its capacity to modulate the psoriatic immune response effectively.

The technological innovation reflected in this work revolves around the integration of stimuli-responsive drug release with oxygen generation—a pioneering approach that mitigates the traditional limitations of topical psoriasis treatments. The ROS-responsive coating acts as a molecular trigger, ensuring drug liberation selectively in the disease microenvironment, thereby sparing healthy tissues. Meanwhile, the oxygen supply mitigates hypoxia-induced resistance, addressing a significant hurdle in achieving sustained therapeutic responses in psoriasis management.

Furthermore, the sustained release profile of triamcinolone acetonide from the PTP nanoparticles is a critical advancement that not only prolongs drug efficacy but also improves patient compliance by reducing the need for frequent applications. This temporal control over drug dosing aligns well with the chronic nature of psoriasis, providing a consistent anti-inflammatory effect that can mitigate flare-ups and maintain disease remission more effectively than conventional formulations.

The microneedle patch design itself offers tangible benefits in terms of patient comfort and usability. By circumventing the stratum corneum barrier through minimally invasive penetration, the patch ensures localized delivery directly to the epidermal and dermal layers where psoriatic pathology is active. This localized administration theoretically reduces systemic drug exposure and minimizes side effects commonly associated with systemic corticosteroid therapies, such as adrenal suppression or skin atrophy.

This innovative platform also holds potential to revolutionize photodynamic therapy for psoriasis. PDT efficacy is greatly contingent upon oxygen availability, an attribute severely compromised in psoriatic tissues due to chronic inflammation and vascular alterations. The localized oxygen release of the S-PTP MN patch effectively reoxygenates the lesion microenvironment, not only augmenting the photochemical reactions central to PDT but also promoting cellular repair mechanisms and further attenuating inflammatory cascades in psoriatic plaques.

The implications of this study extend beyond the immediate clinical benefits for psoriasis patients, representing a versatile strategy for enhancing transdermal drug delivery in other conditions characterized by thickened or impaired skin barriers and hypoxic environments. The dual-section microneedle array, combining responsive drug delivery with in situ oxygen generation, establishes a novel design paradigm that could be adapted for the treatment of diverse chronic inflammatory and ischemic skin disorders.

Moreover, the formulation’s demonstrated efficacy in preclinical models sets the stage for translational research aimed at human clinical trials. Considering the global burden of psoriasis and the limitations of current therapies, the S-PTP MN patch offers a promising, scalable approach that could substantially improve quality of life for patients while alleviating the healthcare costs associated with chronic disease management.

Finally, this study underscores the value of multidisciplinary collaboration, integrating materials science, pharmacology, and dermatology to develop cutting-edge solutions for complex diseases. The synergy between nanotechnology, responsive biomaterials, and targeted therapy heralds a future where personalized, on-demand treatments become the standard of care in dermatological practice and beyond.

Subject of Research: Advanced drug delivery systems for psoriasis treatment

Article Title: Oxygen-boosted dual-section microneedle patch for enhanced drug penetration and improved photodynamic and anti-inflammatory therapy in psoriasis

News Publication Date: 2025

Web References:

• Acta Pharmaceutica Sinica B: https://www.sciencedirect.com/journal/acta-pharmaceutica-sinica-b
• DOI: http://dx.doi.org/10.1016/j.apsb.2025.09.037

Keywords: Psoriasis, Microneedle, Responsive release, Drug delivery, Oxygen, Reactive oxygen species, Sustained release, Triamcinolone acetonide