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How to Choose a Firming Serum by Ingredient
SKINCARE GUIDE
Firming serums can be built around very different ingredients. Instead of choosing by one buzzword, compare what the formula is built around, how it feels on skin, and where it fits in your routine.

01 — START HERE
What should you look for in a firming serum?
A firming serum is not defined by one ingredient alone. Two products can both be described as “firming” while using very different ingredient systems, textures and recommended routines.
Key ingredient
Check which ingredient or ingredient family the formula is actually built around.
Full formula
Look beyond the hero ingredient and consider the supporting peptides, humectants and soothing ingredients.
Texture
Choose a texture that fits the rest of your skincare routine and the way you prefer to layer products.
How you use it
Follow the product’s recommended amount, frequency and skincare step rather than applying every active in the same way.

02 — RETINAL
Retinal
Retinal is part of the vitamin A retinoid family. It is commonly used in skincare formulated to address the appearance of texture, fine lines and loss of firmness.
Retinoid formulas can differ significantly in concentration, texture and recommended frequency, so the product directions matter as much as the ingredient name itself.
Check the exact retinoid used, the concentration if disclosed, how often the product is intended to be used, and how it fits with the rest of your routine.

03 — PEPTIDES
Peptides
Peptides are short chains of amino acids, and skincare formulas can use many different peptide types and combinations. That means “peptide serum” is a broad category rather than one standardized formula.
TOUN28 Peptacica Serum, for example, combines Centella asiatica with peptide-based care in a lightweight serum designed around hydration, texture and elasticity support.
View Peptacica Serum
04 — COPPER PEPTIDES
Copper Peptides & GHK-Cu
Copper peptides are peptides bound to copper ions. GHK-Cu is a well-known copper-peptide complex, while Copper Tripeptide-1 is the cosmetic ingredient name commonly used for this category in ingredient lists.
If you are specifically comparing copper peptide serums, look for the exact ingredient name, the disclosed amount when available, the complete formula and the product texture.
TOUN28 1% Blue Peptide Cica Serum contains 5,000 ppm GHK-Cu (Copper Tripeptide-1) together with seven additional peptides in a dual-layer solid serum formula.
View Blue Peptide Cica Serum05 — PDRN
PDRN
PDRN is a term used for polydeoxyribonucleotide material made from DNA fragments. In skincare, products described as PDRN can differ by source, processing, supporting ingredients and formulation format.
Because of those differences, “contains PDRN” alone is not enough to compare two formulas. Check the ingredient list and the complete product description rather than assuming all PDRN skincare is equivalent.
06 — INGREDIENT COMPARISON
What’s the difference among anti-aging ingredients?
| Blue Peptide (Copper peptide, GHK-Cu) |
Retinol | Collagen | PDRN | |
|---|---|---|---|---|
| What is it? | A copper-binding tripeptide, also known as Copper Tripeptide-1 | A vitamin A derivative | A structural protein naturally found in skin | DNA-derived fragments, commonly sourced from salmon |
| What is it best known for? | Firmness, elasticity & skin texture | Fine lines, texture & uneven tone | Hydration & surface plumping | Skin recovery, hydration & elasticity-focused care |
| How does it work? | GHK-Cu is studied for signaling related to collagen, elastin and extracellular-matrix | Influences skin-cell turnover and collagen-related pathways | Topical collagen mainly forms a moisturizing film; hydrolyzed peptides vary by size | PDRN activity depends heavily on molecular weight, formulation and delivery |
| How easy is topical delivery? | Much smaller than native collagen or PDRN, although formulation still matters for skin delivery | Relatively small molecule | Native collagen is too large to readily penetrate the stratum corneum; hydrolyzed forms vary | Large molecular range makes topical delivery highly formulation-dependent |
| Is it gentle enough for daily use? | Well suited to a peptide-focused daily routine; individual tolerance can vary | Can cause dryness, redness or irritation; gradual introduction is often recommended | Generally gentle | Generally positioned as gentle, but products vary |
| Good choice for sensitive skin? | Yes | △ Depends on tolerance | Yes | Yes |
| Typical skincare price positioning2 | Extremely High | Low–Mid | Low–Mid | Mid–High |
| Evidence maturity | Strong biological rationale and growing cosmetic evidence, but fewer large clinical trials than retinoids | Very established | Established for moisturization; topical structural effects depend on collagen type/size | Growing rapidly, but topical evidence and formulations remain heterogeneous |
07 — HOW TO CHOOSE
Choose by what you want the formula to do in your routine.
Consider it when you want a vitamin A–based routine. Compare the exact retinoid, concentration and recommended frequency.
Consider peptide serums when you want a peptide-focused formula. Compare the actual peptide blend rather than the word “peptide” alone.
Consider this category when you are specifically looking for GHK-Cu or Copper Tripeptide-1. Compare the full formula, disclosed concentration and texture.
Check the source and complete formulation. The label “PDRN” by itself does not make different products directly comparable.
08 — TOUN28 OPTIONS
Two different ways to approach a firming serum.
Within TOUN28’s Global store, Peptacica Serum and Blue Peptide Cica Serum take different formulation approaches.
PEPTIDE + CICA
Peptacica Serum
A lightweight serum built around Centella asiatica and peptide care, with a focus on hydration, texture and elasticity support.
Explore Peptacica Serum
GHK-Cu + PEPTIDES
Blue Peptide Cica Serum
A dual-layer solid serum with 5,000 ppm GHK-Cu (Copper Tripeptide-1) plus seven additional peptides.
Explore Blue Peptide Cica SerumFAQ
Still wondering?
Is a peptide serum the same as a copper peptide serum?
Not necessarily. “Peptide serum” is a broad category. Copper peptide serums specifically use peptides complexed with copper, such as GHK-Cu.
What should I check when choosing a copper peptide serum?
Check the ingredient list for Copper Tripeptide-1, the disclosed amount when available, the supporting ingredients, and the texture and recommended step in the routine.
Is a higher ingredient percentage always better?
No single percentage should be used to judge a complete skincare formula. Consider the ingredient system, full formula, texture and intended use together.
Which TOUN28 serum is the copper peptide option?
TOUN28 1% Blue Peptide Cica Serum is the dedicated copper peptide serum option, with 5,000 ppm GHK-Cu (Copper Tripeptide-1) plus seven additional peptides.