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Recent Submissions
Mechanisms of Laser Ablation in Liquids and Their Impact on the Efficiency of Nanoparticle Generation
(2026) Spellauge, Maximilian; Redka, David; Podhrazsky, Alexander; Eckmann, Katharina; Eulenkamp, Constanze; Koepp, Oliver; Doñate-Buendia, Carlos; Gökce, Bilal; Barcikowski, Stephan; Huber, Heinz Paul
Laser ablation in liquid is a versatile and environmentally friendly method for producing nanoparticles from a wide range of materials. While recent advances have significantly increased productivity, laser ablation in liquid remains less energy-efficient than ablation in air. Simulations have suggested that this discrepancy arises from the redeposition of ablated material, but experimental validation has so far been lacking. Here, we quantify the energy efficiency of laser ablation in liquid and provide direct experimental verification of redeposition. An absorption-corrected one-to-one comparison of single-pulse ablation in air and water shows that the absorption-corrected specific energy for ablation increases fourfold in water due to redeposition, from 50 J mm-3 to 200 J mm-3. For multi-pulse conditions, the required energy for ablation based on the incident pulse energy amounts to 431 J mm-3, corresponding to an order-of-magnitude improvement compared to the best ultrafast LAL value of 3333 J mm-3 reported to date. These findings establish the practical potential of LAL for green and energy-efficient nanoparticle synthesis.
Time-resolved probing and modeling of optical signatures of ultrashort-pulse laser spallation and phase explosion in iron-nickel targets
(2025) Chen, Chaobo; Spellauge, Maximilian; Redka, David; Auer, Ramon; Doñate-Buendia, Carlos; Barcikowski, Stephan; Gökce, Bilal; Huber, Heinz Paul; Zhigilei, Leonid V.
Time-resolved microscopy is an established technique for probing the dynamics of laser ablation, thus enabling the exploration of material behavior under extreme conditions produced by laser excitation. Decoding the time-resolved data on the rapid variation of optical properties of a material undergoing nonequilibrium phase decomposition and ejection, however, presents a significant challenge. In this paper, a closely integrated computational and experimental study of laser ablation of FeNi targets is used to establish direct links between the dynamics of laser ablation and the evolution of optical signal in pump-probe experimental measurements. The experiments and large-scale atomistic simulations are performed for a range of fluences covering the onset of material ejection at the threshold for photomechanical spallation and the transition to the phase explosion regime of laser ablation. The connections between the simulations and experiments are established through numerical modeling of the interaction of an electromagnetic wave representing the experimental probe laser pulse with transient states of the ablation plume predicted in the atomistic simulations. The combined modeling and experiments have revealed a complex interplay of processes defining the transient optical properties of the emerging ablation plume, including the oscillations of reflectance due to the interference of parts of the probe pulse reflected from the spalled layer and the newly formed surface of the target in the spallation regime, the disappearance of the interference pattern upon the transition to the regime of phase explosion, nonmonotonous variation of the refractive index of a transient spongy structure of interconnected liquid regions, and the formation of nanoscale hot spots within the expanding spongy structure due to the near-field concentration of electromagnetic field. The results of this study not only provide reliable guidance for the interpretation of optical signals measured in pump-probe experiments but also suggest new ideas for manipulating the ablation plume dynamics to achieve higher efficiency and precision in laser synthesis and processing of materials in the double-or multipulse irradiation regimes.
Time-resolved probing of laser-induced nanostructuring processes in liquids
(2025) Spellauge, Maximilian; Redka, David; Mo, Mianzhen; Song, Changyong; Huber, Heinz Paul; Plech, Anton
Laser synthesis and processing of colloids (LSPC) in liquids has gained widespread applications in producing nanomaterials of different classes of solids. While the technical processes in different cases of ablation, fragmentation or colloidal fusion may look macroscopically different in each application, the underlying fundamental mechanisms are always the same cascade of laser interaction with matter, non-thermal or thermal energy deposition, phase transitions, and the subsequent structure formation processes. Disentangling these mechanisms represents a veritable challenge, as ultrafast and structurally sensitive experimental methods are required. This review presents a discussion of how state-of-the-art experimental protocols using ultrafast lasers and sensitive structural probes, such as electrons or X-rays are able to address this challenge. In particular, it is possible to investigate LSPC on single objects using single probe pulses and avoid accumulation effects in a heterogeneous sample. The presented results capture structure formation with femtosecond and atomic scale resolution. Ultrafast time-resolved probing approaches are key to revealing the transient states and pathways that govern material transformation in LSPC.
Multifunctional implantable hydrogels: Smart platforms at the forefront of biomedical innovation
(2026) Nagay, Bruna E.; Mamizadeh Janghour, Leila; El-Khordagui, Labiba K.; Akhavan, Behnam; Barão, Valentim A.R.; Dananjaya, Vimukthi; Abeykoon, Chamil; El-Habashy, Salma E.; Dodda, Jagan Mohan
Hydrogels are transformative three-dimensional polymeric networks that replicate the extracellular matrix owing to their high-water content, biocompatibility, and tunable physicochemical properties. Evolving beyond conventional applications in wound dressings, contact lenses, and basic drug depots, hydrogel systems have advanced into implantable designs capable of long-term physiological integration. Surgically placed or delivered via minimally invasive techniques, implantable hydrogels (IHGs) enable dynamic tissue interactions, biodegradability, self-healing behaviour, and sustained drug release. The emergence of multifunctional, stimuli-responsive variants of IHGs has further expanded their therapeutic, diagnostic, and regenerative potential while preserving their essential material attributes. By coupling stimuli responsiveness with patient-specific physiological cues, IHGs embody the "smart" nature of next-generation biomaterials, advancing personalized medicine through adaptive therapeutic delivery, real-time functional responsiveness, and dynamic biological integration. This review summarizes recent progress in the design and fabrication of IHGs, emphasizing 3D and 4D printing technologies and the development of hydrogel inks optimized for mechanical robustness, shape fidelity, and biological performance. Applications are discussed across four major areas: (i) hydrogel coatings for medical implants, (ii) injectable hydrogels for infection control, (iii) bone-regenerative scaffolds, and (iv) health-monitoring systems. Finally, the review addresses key translational challenges, including scalable manufacturing, long-term stability, and regulatory considerations, while outlining future directions toward smart, multifunctional implantable hydrogels capable of integrated biosensing and responsive therapeutic delivery. Distinct from previous reviews, this work combines implantability and multifunctionality/smartness within a single framework, highlighting how hydrogels can achieve durable physiological integration while dynamically adapting to patient-specific cues.
Next-generation epidermal patches: Bridging 3D and multidimensional printing for biomedical and personal care innovations
(2026) El-Khordagui, Labiba K.; El-Habashy, Salma E.; Simchi, Abdolreza; Tohamy, Hebat-Allah S.; Focarete, Maria Letizia; Rea, Mariangela; Di Lisa, Luana; Barman, Snigdha Roy; Nain, Amit; Catanzano, Ovidio; Boateng, Joshua; Dodda, Jagan Mohan
Advances in additive manufacturing, particularly 3D and multidimensional printing, have enabled unprecedented control over the architecture, composition, and bioactivity of epidermal patches. These developments have broadened the scope of epidermal patches across biomedical and personal-care applications, supporting personalized and adaptive solutions for drug delivery, wound management, tissue regeneration, and skin-related interventions. This review summarizes next-generation printed epidermal patches, covering both conventional (non-microneedle) systems and microneedle-integrated platforms. Particular emphasis is placed on emerging material systems, including self-oxygenating hydrogels, nanomaterial-free bioinks derived from proteins and polysaccharides, and functional nanocomposite formulations. We examine key 3D printing strategies for fabricating acellular constructs, cell-laden matrices, and microneedle array patches (MAPs), alongside recent advances in multidimensional printing technologies. Biomedical applications are discussed with a focus on dermal and transdermal drug delivery, particularly insulin delivery for diabetes management as well as wound repair, regenerative therapies, photodynamic treatments, and biosensing. Additionally, the integration of printed epidermal patches with wearable sensors, smart devices, and artificial intelligence (AI) is highlighted as an emerging frontier in intelligent skin-interfaced systems, with implications for both healthcare and advanced personal-care technologies. Finally, key challenges related to clinical translation, regulatory pathways, and commercialization are addressed, providing strategic insights to guide the advancement of hydrogel-based additive manufacturing from laboratory innovation to real-world clinical and aesthetic applications.