This work is supported by the Department of Science and Technology - Philippine Textile Research Institute under the DOST Grants-in-Aid (DOST-GIA) Project entitled Covert Technology Towards Sustainability and Protection of the Philippine Textile Sectors under the Digitalization of the Philippine Handloom Weaving Industry Program.

1. Extraction of curcumin
<ol>
	<li>Weigh 3 g of C. longa powder in a 50 mL centrifuge tube. 
	NOTE: A 50 mL centrifuge tube was used to ease the centrifugation process and process the extraction on a single container.</li>
	<li>Add 38 mL of ethanol (AR, 99%) to the centrifuge tube. Shake the tube gently to ensure thorough mixing of ethanol with the C. longa powder.</li>
	<li>Sonicate the tube for 30 min at normal sonic mode and high intensity setting for extraction.</li>
	<li>To...

Use of Chitosan to Enhance Photoluminescence of Curcumin for Textile Authentication

Textile finishing is a common practice within the industry in order to incorporate additional functional properties onto the fabrics, making them more suitable for specific applications45,47,48. In this study, the extracted curcumin was utilized as a natural dye to serve as authentication mechanisms for textile applications. The protocols give emphasis not only to the extraction of curcumin from turmeric, but also to the differe...

Counterfeiting is considered a scourge in widespread industries across the globe. The rapid surge of counterfeit products in the market causes economic havoc, which impedes the livelihood of the primary inventor1,2,3,4,5,6. This was brought to the fore in 20207&#160;on the ongoing concern of emerging counterfeit products as evidenced by the increasing trend of publications consisting of the keyword anticounterfeiting or counterfeiting in their titles. A significant increase can be observed in counterfeit-related publications since last reported in 2019, suggesting that considerable efforts are being made to combat the production and distribution of fraudulent goods. On the other hand, it can also be quite alarming, given that it signifies the progression of the counterfeiting industry, which is expected to persist if not addressed effectively. The textile industry is not insulated from this problem, as the presence of counterfeit textile products has severely impacted the livelihood of genuine sellers, manufacturers and weavers, among others3,8. For instance, the textile industry in West Africa was long considered one of the leading export markets in the world. However, it was reported9&#160;that approximately 85% of the market share is held by smuggled textiles that infringe upon West African textile trademarks. The effects of counterfeiting have also been reported in other continents like Asia, America, and Europe, indicating that this crisis has reached an uncontrollable level and poses a significant threat to the already struggling textile industry2,3,4,10,11,12.
With the rapid advancements of science, technology, and innovation, researchers took upon the role of developing functional materials for the purpose of anti-counterfeiting applications. The use of covert technology is one of the most common and effective approaches to counteract the production of fraudulent goods. It involves utilizing photoluminescent materials as security dyes that exhibit a specific light emission when irradiated by different wavelengths13,14. However, some photoluminescent dyes available in the market may impose toxicity at high concentrations, thereby posing threats to human health and the environment15,16.
Turmeric (Curcuma longa) is an essential plant used in myriad applications such as paints, flavoring agents, medicine, cosmetics, and fabric dyes17. Present in the rhizomes are naturally occurring phenolic chemical compounds called curcuminoids. These curcuminoids include curcumin, demethoxycurcumin, and bisdemethoxycurcumin, among which curcumin is the main constituent responsible for the vibrant yellow to orange coloration and the properties of turmeric18. Curcumin, otherwise known as 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione19,20&#160;with an empirical formula of C21H20O6, has attracted a significant amount of attention in the biomedical and pharmaceutical fields due to its antiseptic, anti-inflammatory, anti-bacterial, and antioxidant properties17,18,21,22,23. Interestingly, curcumin also possesses spectral and photochemical characteristics. Particularly noteworthy is its intense photoluminescent properties when subjected to ultraviolet (UV) excitations which have been explored only by a few studies19,24,25. Given these characteristics, in tandem with its hydrophobic nature and non-toxic properties, curcumin emerges as an ideal colorant for authentication markings.
The extraction of curcumin from turmeric was first reported in the early 1800s. Over the past centuries, numerous extraction methodologies and techniques have been devised and improved to achieve higher yield26,27,28,29,30,31,32,33. Conventional solvent extraction is a widely used approach as it employs organic solvents such as ethanol, methanol, acetone, and hexane among others, to isolate curcumin from turmeric34,35. This method has evolved through modifications, coupled with more advanced techniques such as microwave-assisted extraction (MAE)18,36,37, Soxhlet extraction38,39, enzyme-assisted extraction (EAE)39,40, and ultrasonic extraction36, among others to increase the yield. Generally, the solvent extraction method has been applied for natural dye extraction due to its versatility, low energy requirement, and cost-effectiveness making it ideal for scalable industries such as textiles.
Curcumin has been integrated as natural dyes for textiles due to its distinct yellow hue. However, the poor adsorption of natural dyes unto textile fibers pose as a challenge that hinders its commercial viability41. Mordants, such as metals, polysaccharides, and other organic compounds, serve as common binders to strengthen the affinity of natural dyes unto the fabric. Chitosan, a polysaccharide derived from crustaceans, has been widely utilized as an alternative mordanting agent due to its abundance in nature, biocompatibility, and wash durability42. This study reports a facile and straight forward approach in preparing curcumin-based authentication marking. Crude curcumin extracts were obtained via sonication-assisted solvent extraction method. The photoluminescent properties of the extracted curcumin were comprehensively investigated on textile substrates and further enhanced with the introduction of chitosan as a mordanting agent. This demonstrates the significant potential as a naturally derived photoluminescent dye for authentication applications.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>(Curcumin) C. longa, spray dried&#160;</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Naturally Sourced</td>
		</tr>
		<tr>
			<td>100 mL Graduated Cylinder</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>10 mL Serological Pipette</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>200 mL Beaker</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>365 nm UV Light</td>
			<td>AloneFire</td>
			<td></td>
			<td>SV004 LG</td>
		</tr>
		<tr>
			<td>50 mL Centeifuge Tube</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AATCC Multitester Fabric</td>
			<td>Testfabrics, Inc.</td>
			<td>401002</td>
			<td>AATCC Multifiber test fabric # 1 precut pieces of 2 X 2 inches, Heat Sealed</td>
		</tr>
		<tr>
			<td>Analytical Balance</td>
			<td>Satorius</td>
			<td></td>
			<td>BSA 224S-CW</td>
		</tr>
		<tr>
			<td>Aspirator</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ATR- FTIR</td>
			<td>Bruker</td>
			<td></td>
			<td>Bruker Tensor II</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Hermle Labortechnik GmbH</td>
			<td></td>
			<td>Z 206 A</td>
		</tr>
		<tr>
			<td>Chitosan</td>
			<td>Tokyo Chemical Industries</td>
			<td>9012-76-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital&#160; Camera</td>
			<td>ToupTek</td>
			<td></td>
			<td>XCAM1080PHB</td>
		</tr>
		<tr>
			<td>Drying Rack</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Chem-Supply</td>
			<td>64-17-5</td>
			<td>Undenatured, 99.9% purity</td>
		</tr>
		<tr>
			<td>Glacial Acetic Acid</td>
			<td>RCI-Labscan</td>
			<td>64-19-7</td>
			<td>AR Grade, 99.8% purity</td>
		</tr>
		<tr>
			<td>Glass Slide</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Iron Clamp</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Iron Stand</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic Stirrer</td>
			<td>Corning</td>
			<td></td>
			<td>PC-620D</td>
		</tr>
		<tr>
			<td>Pasteur Pipette</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Propan-2-ol</td>
			<td>RCI-Labscan</td>
			<td>67-63-0</td>
			<td>AR Grade, 99.8% purity</td>
		</tr>
		<tr>
			<td>Sonicator</td>
			<td>Jeio Tech Inc.</td>
			<td></td>
			<td>UCS-20</td>
		</tr>
		<tr>
			<td>Spectrofluorometer&#160;</td>
			<td>Horiba (Jovin Yvon)</td>
			<td></td>
			<td>Horiba Fluoromax Plus</td>
		</tr>
		<tr>
			<td>Stirring Bar</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>UV-Vis Spectrophotometer</td>
			<td>Agilent</td>
			<td></td>
			<td>Cary UV 100</td>
		</tr>
		<tr>
			<td>Wash bottle</td>
			<td>n/a</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zoom Stereo Microscope</td>
			<td>Olympus</td>
			<td></td>
			<td>SZ61</td>
		</tr>
	</tbody>
</table>

enhanced photoluminescence of curcuma longa extracts via chitosan-mediated energy transfer for textile authentication applications

Dyes for security markings play a pivotal role in safeguarding the integrity of products across various fields, such as textiles, pharmaceuticals, food, and manufacturing among others. However, most commercial dyes used as security markings are costly and may contain toxic and harmful substances that pose a risk to human health. Curcumin, a natural phenolic compound found in turmeric, possesses distinct photoluminescent properties alongside its vibrant yellow color, making it a potential candidate material for authentication applications. This study demonstrates a cost-effective and eco-friendly approach to develop enhanced photoluminescent emissions from curcumin dyes for textile authentication. Curcumin was extracted from C. longa using sonication-assisted-solvent extraction method. The extract was dip-coated and dyed into the textile substrates. Chitosan was introduced as a post-mordanting agent to stabilize the curcumin and as a co-sensitizer. Co-sensitization of curcumin with chitosan triggers energy transfer to enhance its luminescent intensity. The UV-visible absorption peak at 424 nm is associated with the characteristic absorption of curcumin. The photoluminescence measurements showed a broad emission peaking at 545 nm with significant enhancement attributed to the energy transfer induced by chitosan, thus showing great potential as a naturally derived photoluminescent dye for authentication applications.

Enhanced Photoluminescence of Curcuma longa Extracts via Chitosan-Mediated Energy Transfer for Textile Authentication Applications

FTIR analyses of fibers determine the chemical structure of each fiber represented in the multi-tester fabrics #1. FTIR spectroscopy was utilized in order to characterize the functional groups present in each component of the multi-test fabrics. As shown in Supplementary Figure 1, the distinction occurs due to the presence of N-H functional groups, which leads to the fabric being subcategorized into nitrogenous (Supplementary Figure 1A) ...

Watch this Scientific Journal Video about Enhanced Photoluminescence of Curcuma longa Extracts via Chitosan-Mediated Energy Transfer for Textile Authentication Applications at JoVE.com

Author Spotlight: Eco-friendly Photoluminescent Textile Authentication with Curcumin

Photoluminescence is one of the most effective authentication mechanisms being used today. Utilizing and enhancing naturally sourced materials with inherent photoluminescent properties and incorporating them into fabric substrates can lead to development of green, sustainable, and functional textiles for smart applications.

Dyes for security markings play a pivotal role in safeguarding the integrity of products across various fields, such as textiles, pharmaceuticals, food, ...