Thesis (Ph.D)-Cairo University, 2024.

Bibliography: pages 100-114.

Melanin is a natural photothermal biopolymer. It is considered the main chromophore for laser hair
removal. The insolubility of melanin as an exogenous dye, in most solvents, limits its bioavailability and
thus its clinical use. Melanin was extracted from a sepia ink sac and prepared as insoluble powdered sepia
melanin (SM) which is identified by FTIR, 1H-NMR, thermogravimetric analysis (TGA), and scanning
electron microscope (SEM). In our study, to overcome the solubility problems and increase the
bioavailability of melanin for biomedical and cosmetic applications, SM was self-assembled using tween
80 into dispersed nanoparticles (SM-NP-Tw). Moreover, natural sepia melanin was loaded in different
delivery systems (spanlastics and transfersomes) to be delivered to the hair follicles. The prepared SM-NP-
Tw were fully characterized. The photothermal performance of SM-NP-Tw was assessed. Dark and
photocytotoxicity of SM-NP-Tw was studied on HepG2 cells using two wavelengths (660 nm and 820 nm).
The insoluble powdered (SM) exhibited a spherical nanoparticle-like shape as revealed by scanning electron
microscope and was soluble only in an alkaline aqueous solution. TGA of SM showed high resistance to
thermal degradation indicating good thermal stability. The prepared SM-NP-Tw exhibited a spherical shape
with mean sizes of 308±86 nm and a zeta potential of −25 mv. The cell viability decreased significantly
upon increasing the concentration and upon radiation at 820 nm. The results of UV–Vis spectroscopy and
the photothermal performance revealed that melanin can absorb light in a wide range of wavelengths
including near the IR region; thus, it can emit sufficient heat to kill cells through the photoheat conversion
effects. Melanin spanlastics and transfersomes were prepared and characterized. Transmission electron
microscopy (TEM) showed the spherical shape of the prepared vesicles with average particle sizes 252 and
262 nm and zeta potential of -22.5 and -35 mV for melanin spanlastics and melanin transfersomes,
respectively. Histological examination of hair follicles and pilosebaceous glands for the irradiated and non-
irradiated albino mice skin was studied after the application of the prepared formulations topically and
subcutaneously. Qualitative statistical analysis was conducted and melanin transfersomes and melanin
spanlastics showed significant damage to pilosebaceous glands and hair follicles with a p-value of 0.031
and 0.009 respectively. Sepia melanin nanoparticles self-assembled into tween-based nanostructures could
be a promising natural platform for different applications including photothermal cancer therapy. As well,
melanin nanoparticles loaded in transfersomes and spanlastics could be considered a promising approach
for the laser removal of non-pigmented hair.

إن الهدف من هذه الرسالة هو تحضير الميلانين في أنواع مختلفة من موصلات الدواء. الميلانين هو بوليمر حيوي حراري ويعتبر الكروموفور الرئيسي لإزالة الشعر بالليزر. و لكن عدم قابلية ذوبان الميلانين كصبغة خارجية ، في معظم المذيبات ، يعد مشكلة كبيرة تحد من توافره البيولوجي وبالتالي استخدامه اكلينيكيا. تم استخراج الميلانين من الحبار وتحضيره كمسحوق غير قابل للذوبان (SM) و تمت دراسته. ولكى نتغلب على مشاكل الذوبان وزيادة التوافر البيولوجي للميلانين ، تم تحضيره في جسيمات نانوية ، وتم تحميل الميلانين في موصلات دواء مختلفة ليتم توصيل الميلانين إلى بصيلات الشعر.تم دراسة الخواص الصيدلية للميلانين و تقييم الأداء الحراري الضوئي لها. أيضا تم دراسة سمية الميلانين على الخلايا السرطانية فى المعمل في الظلام و فى وجود الضوء باستخدام جهاز ليزربطوليين موجيين (660 نانومتر و 820 نانومتر).

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