Activated Metals to Generate Heat for Biomedical Applications.

Delivering heat in vivo could enhance a wide range of biomedical therapeutic and diagnostic technologies, including long-term drug delivery devices and cancer treatments. To date, providing thermal energy is highly power-intensive, rendering it oftentimes inaccessible outside of clinical settings. We developed an in vivo heating method based on the exothermic reaction between liquid-metal-activated aluminum and water. After establishing a method for consistent activation, we characterized the heat generation capabilities with thermal imaging and heat flux measurements. We then demonstrated one application of this reaction: to thermally actuate a gastric resident device made from a shape-memory alloy called Nitinol. Finally, we highlight the advantages and future directions for leveraging this novel in situ heat generation method beyond the showcased example.

Actively Triggerable Metals via Liquid Metal Embrittlement for Biomedical Applications.

Actively triggerable materials, which break down upon introduction of an exogenous stimulus, enable precise control over the lifetime of biomedical technologies, as well as adaptation to unforeseen circumstances, such as changes to an established treatment plan. Yet, most actively triggerable materials are low-strength polymers and hydrogels with limited long-term durability. By contrast, metals possess advantageous functional properties, including high mechanical strength and conductivity, that are desirable across several applications within biomedicine. To realize actively triggerable metals, a mechanism called liquid metal embrittlement is leveraged, in which certain liquid metals penetrate the grain boundaries of certain solid metals and cause them to dramatically weaken or disintegrate. In this work, it is demonstrated that eutectic gallium indium (EGaIn), a biocompatible alloy of gallium, can be formulated to reproducibly trigger the breakdown of aluminum within different physiologically relevant environments. The breakdown behavior of aluminum after triggering can further be readily controlled by manipulating its grain structure. Finally, three possible use cases of biomedical devices constructed from actively triggerable metals are demonstrated.

Comparison of quality of facial scars after single low-level laser therapy and combined low-level with high-level (PDL 595 nm) laser therapy.

The main goal of our study was to compare the quality of resulting facials scar 12 weeks after single and combined laser therapy. Forty-one children from age 1.5 to 5 years with facial scars after injury participated in the study. Thirty-one underwent laser therapy, 14 were treated using single low-level laser therapy (670 nm, fluence 3-5 J/cm(-2) ), and 17 underwent combined high-level laser therapy with non-ablative pulsed dye laser (PDL; 595 nm, spot size 7 mm, delay 0.45 ms or 1.5 ms, fluence 9-11 J/cm(-2) , cryogen spray/delay 20/30 ms) and low-level laser therapy. The control group consisted of 10 untreated children. Before treatment and at week 4, 8, and, 12 the scars were evaluated using the POSAS questionnaire. A statistically significant improvement in scars (between ratings before treatment and 4 weeks after therapy, before treatment and 8 weeks after therapy and before treatment and 12 weeks after therapy) was observed in all parameters in both treatment groups (p < 0.0001). For the HLLT+LLLT group the most significant enhancement in the quality of scars was found for all items and at all evaluations, except pigmentation and pliability. There was no improvement observed in quality of facial scars in the control group.

Hemangioma curative effect of PDL, alexandrite, Er:YAG and CO(2) lasers.

OBJECTIVE: Hemangioma is a mesenchymal benign tumor formed by blood vessels. Anomalies affect up to 10% of children and they are more common in females than in males. The aim of this study was to evaluate hemangioma treatment using four different types of lasers, namely, alexandrite, Er:YAG, CO(2), and pulsed dye laser (PDL). BACKGROUND DATA: The argon laser was the first to be used for dermatological patients, namely, with port wine stains (PWS) in the late 1960s and early 1970s. A variety of different lasers and light sources were useful in the treatment of vascular lesions, e.g., KTP, Nd:YAG, CO(2), PDL, and Er:YAG. METHODS: A group of 869 consecutive patients with hemangioma was retrospectively reviewed. The patients including in our study were divided into four groups according to the type of laser used: Alexandrite laser (n=85, 58 women and 20 men), CO(2) laser (n=78, 58 women and 20 men), Er:YAG laser (n=105, 87 women and 18 men), and PDL laser (n=601, 453 women and 148 men). All patients were treated in one session without anesthesia application. The ablative systems vaporized the tissues until the hemangioma was removed. The non-ablative systems used one shot, which destroyed the hemangioma blood vessels. RESULTS: For the treatment efficacy analysis, the following factors were evaluated: therapeutic effect (yes vs. no), loss of pigment (yes vs. no), and appearance of scar (yes vs. no). From results it was evident that the therapeutic effect of all the lasers except alexandrite was very high; almost 100%. In the CO(2) and the Er:YAG laser groups a high percentage of side effects was also observed. Exposure to these lasers caused loss of pigment and scar formation in many cases. The best therapeutic effect, with only minor side effects, has been achieved with the PDL laser. CONCLUSION: It was confirmed that PDL (595 nm, 1.5 ms, 7 mm, 9 - 11 J/cm(2)) had optimal effect without scars. Er:YAG or CO(2) laser radiation with specific characteristics was also useful for small superficial lesions.