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Targeting & Delivery Peptides

Custom synthesis of peptide sequences designed for cellular uptake, tissue targeting, receptor recognition, membrane insertion, organelle localization, blood–brain barrier transport, and endosomal escape.

Cell-Penetrating Peptides Tumor-Homing Peptides BBB Shuttle Peptides pHLIP Organelle Targeting Endosomal Escape
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Overview Peptide Families Sequence Library Design Considerations Related Services FAQ Contact
Overview

Select the Peptide Around the Biological Route

Targeting and delivery peptides are selected according to the biological barrier or destination that must be addressed. Some sequences promote nonspecific cellular uptake, while others recognize a receptor, home to tumor-associated tissue, insert into membranes at low pH, cross biological barriers, or help a payload escape from endosomes.

These peptides can be synthesized alone or incorporated into multifunctional constructs containing fluorescent dyes, affinity tags, lipids, PEG spacers, cleavable linkers, oligonucleotides, proteins, nanoparticles, or small-molecule payloads.

Design principle: peptide sequence alone does not determine delivery performance. Cargo size, attachment site, linker architecture, peptide orientation, charge, hydrophobicity, formulation, and assay model can all influence biological behavior.

Targeting and delivery peptide pathways from extracellular recognition to intracellular destination A multifunctional peptide cargo construct moves through receptor targeting, membrane transport, endosomal escape, and organelle delivery pathways. TARGETING & DELIVERY PATHWAYS Sequence selection follows the biological barrier, destination, and cargo. Tissue Targeting RGD · NGR · BBB shuttles Receptor recognition or tissue homing Peptide–Cargo Construct Targeting peptide + linker + payload Cellular Uptake TAT · Penetratin · R8/R9 Direct translocation or endocytosis CELL MEMBRANE Endosome escape Cytosol Organelle Receptor Targeting Membrane Transport Endosomal Escape Organelle Delivery
The same peptide may support more than one step, but targeting, uptake, endosomal escape, and intracellular trafficking should be evaluated as separate design requirements.
Interactive Peptide Family Guide

Explore Targeting and Delivery Peptide Classes

Select a family to view representative peptides and sequences. Catalog-page links can be added later to each peptide name or arrow.

Cell-Penetrating Peptides

Cationic, amphipathic, or membrane-interacting sequences used to promote cellular uptake of peptides and conjugated cargos.

HIV-1 TAT

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CPP
YGRKKRRQRRR

Function: Cationic cellular uptake

Typical use: Peptide, protein, ASO, and siRNA delivery

Penetratin

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CPP
RQIKIWFQNRRMKWKK

Function: Membrane translocation

Typical use: Intracellular delivery and imaging

Transportan

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CPP
GWTLNSAGYLLGKINLKALAALAKKIL

Function: Amphipathic cellular uptake

Typical use: Cargo and nucleic-acid delivery

Poly-Arginine R8

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CPP
RRRRRRRR

Function: Cationic uptake

Typical use: Cellular delivery and uptake studies

Tumor-Homing Peptides

Peptides selected to recognize tumor-associated receptors, vasculature, extracellular matrix, or tissue microenvironments.

RGD Motif

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Tumor Homing
RGD

Function: Integrin recognition

Typical use: Targeted imaging and delivery

iRGD

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Tumor Penetration
CRGDKGPDC

Function: Integrin binding and tissue penetration

Typical use: Tumor-directed payload delivery

NGR

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Tumor Vasculature
CNGRC

Function: CD13-associated targeting

Typical use: Tumor vascular targeting

CREKA

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Matrix Targeting
CREKA

Function: Fibrin-associated homing

Typical use: Tumor imaging and nanoparticle delivery

Blood–Brain Barrier Peptides

Receptor-binding or shuttle peptides investigated for transport across the blood–brain barrier and CNS delivery.

Angiopep-2

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BBB Shuttle
TFFYGGSRGKRNNFKTEEY

Function: LRP1-associated transport

Typical use: CNS delivery and imaging

ApoE-Derived Peptide

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BBB / Lipoprotein
LRKLRKRLL

Function: Receptor-interacting motif

Typical use: CNS cargo delivery studies

RVG-Derived Peptide

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Neuronal Targeting
YTIWMPENPRPGTPCDIFTNSRGKRASNG

Function: Nicotinic receptor-associated targeting

Typical use: Neuronal and CNS delivery

pHLIP Peptides

pH-responsive membrane-inserting peptides used to target acidic tissues and transport attached cargos across lipid bilayers.

Wild-Type pHLIP

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pH-Responsive
AEQNPIYWARYADWLFTTPLLLLDLALLVDADEGT

Function: Low-pH membrane insertion

Typical use: Acidic tissue targeting and translocation

pHLIP Variant

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pH-Responsive
Sequence varies by design

Function: Tuned insertion and kinetics

Typical use: Tumor targeting and cargo delivery

Nuclear Localization Peptides

Basic sequence motifs recognized by nuclear transport machinery and used to promote nuclear accumulation of conjugated cargos.

SV40 NLS

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NLS
PKKKRKV

Function: Nuclear import signal

Typical use: DNA, protein, and gene-editing cargo delivery

Nucleoplasmin NLS

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Bipartite NLS
KRPAATKKAGQAKKKK

Function: Nuclear localization

Typical use: Nuclear delivery studies

Mitochondrial Targeting Peptides

Amphipathic, cationic, or aromatic-cationic sequences used to direct peptides and payloads toward mitochondria.

SS-31 / Elamipretide

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Mitochondrial
D-Arg-Dmt-Lys-Phe-NH2

Function: Mitochondrial membrane association

Typical use: Oxidative-stress and mitochondrial studies

Mitochondrial Targeting Motif

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MTS
MLSLRQSIRFFKPATRTLCSSRYLL

Function: Mitochondrial import signal

Typical use: Organelle targeting constructs

Endosomal Escape Peptides

Fusogenic or pH-responsive peptides designed to destabilize endosomal membranes and improve cytosolic release.

HA2

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Fusogenic
GLFGAIAGFIENGWEGMIDGWYG

Function: pH-triggered membrane disruption

Typical use: Endosomal escape and cytosolic delivery

INF7

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Fusogenic
GLFEAIEGFIENGWEGMIDGWYG

Function: HA2-derived endosomal disruption

Typical use: RNA and macromolecule delivery

GALA

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pH-Responsive
WEAALAEALAEALAEHLAEALAEALEALAA

Function: Acid-triggered amphipathic helix

Typical use: Gene and nucleic-acid delivery

Membrane-Active Peptides

Amphipathic peptides used to interact with, perturb, or permeabilize lipid membranes in controlled delivery systems.

KALA

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Membrane Active
WEAKLAKALAKALAKHLAKALAKALKACEA

Function: Membrane destabilization

Typical use: Intracellular and nucleic-acid delivery

Melittin

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Membrane Active
GIGAVLKVLTTGLPALISWIKRKRQQ

Function: Membrane permeabilization

Typical use: Mechanistic and delivery research

MPG

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CPP / Fusogenic
GALFLGFLGAAGSTMGAWSQPKKKRKV

Function: Cell entry and cargo transport

Typical use: Oligonucleotide and macromolecule delivery

Representative Sequence Library

Common Targeting and Delivery Peptides

This reference table provides representative sequences and functions. Sequence variants, terminal modifications, stereochemistry, cyclization, and conjugation handles can be customized. If you cannot find the peptide or sequence you need, contact our peptide team for assistance or browse our Catalog Peptide Library for additional peptide families and sequences.

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Peptide Family Representative Sequence Primary Function Typical Use
HIV-1 TAT Cell-Penetrating Peptides YGRKKRRQRRR Cationic cellular uptake Peptide, protein, ASO, and siRNA delivery
Penetratin Cell-Penetrating Peptides RQIKIWFQNRRMKWKK Membrane translocation Intracellular delivery and imaging
Transportan Cell-Penetrating Peptides GWTLNSAGYLLGKINLKALAALAKKIL Amphipathic cellular uptake Cargo and nucleic-acid delivery
Poly-Arginine R8 Cell-Penetrating Peptides RRRRRRRR Cationic uptake Cellular delivery and uptake studies
RGD Motif Tumor-Homing Peptides RGD Integrin recognition Targeted imaging and delivery
iRGD Tumor-Homing Peptides CRGDKGPDC Integrin binding and tissue penetration Tumor-directed payload delivery
NGR Tumor-Homing Peptides CNGRC CD13-associated targeting Tumor vascular targeting
CREKA Tumor-Homing Peptides CREKA Fibrin-associated homing Tumor imaging and nanoparticle delivery
Angiopep-2 Blood–Brain Barrier Peptides TFFYGGSRGKRNNFKTEEY LRP1-associated transport CNS delivery and imaging
ApoE-Derived Peptide Blood–Brain Barrier Peptides LRKLRKRLL Receptor-interacting motif CNS cargo delivery studies
RVG-Derived Peptide Blood–Brain Barrier Peptides YTIWMPENPRPGTPCDIFTNSRGKRASNG Nicotinic receptor-associated targeting Neuronal and CNS delivery
Wild-Type pHLIP pHLIP Peptides AEQNPIYWARYADWLFTTPLLLLDLALLVDADEGT Low-pH membrane insertion Acidic tissue targeting and translocation
pHLIP Variant pHLIP Peptides Sequence varies by design Tuned insertion and kinetics Tumor targeting and cargo delivery
SV40 NLS Nuclear Localization Peptides PKKKRKV Nuclear import signal DNA, protein, and gene-editing cargo delivery
Nucleoplasmin NLS Nuclear Localization Peptides KRPAATKKAGQAKKKK Nuclear localization Nuclear delivery studies
SS-31 / Elamipretide Mitochondrial Targeting Peptides D-Arg-Dmt-Lys-Phe-NH2 Mitochondrial membrane association Oxidative-stress and mitochondrial studies
Mitochondrial Targeting Motif Mitochondrial Targeting Peptides MLSLRQSIRFFKPATRTLCSSRYLL Mitochondrial import signal Organelle targeting constructs
HA2 Endosomal Escape Peptides GLFGAIAGFIENGWEGMIDGWYG pH-triggered membrane disruption Endosomal escape and cytosolic delivery
INF7 Endosomal Escape Peptides GLFEAIEGFIENGWEGMIDGWYG HA2-derived endosomal disruption RNA and macromolecule delivery
GALA Endosomal Escape Peptides WEAALAEALAEALAEHLAEALAEALEALAA Acid-triggered amphipathic helix Gene and nucleic-acid delivery
KALA Membrane-Active Peptides WEAKLAKALAKALAKHLAKALAKALKACEA Membrane destabilization Intracellular and nucleic-acid delivery
Melittin Membrane-Active Peptides GIGAVLKVLTTGLPALISWIKRKRQQ Membrane permeabilization Mechanistic and delivery research
MPG Membrane-Active Peptides GALFLGFLGAAGSTMGAWSQPKKKRKV Cell entry and cargo transport Oligonucleotide and macromolecule delivery

Sequence note: sequences are shown in the standard N-to-C direction unless otherwise stated. D-amino acids, amidation, cyclization, lipidation, PEG spacing, or other modifications should be explicitly defined during quoting.

Design Considerations

Build the Construct Around Cargo and Biological Destination

Targeting and delivery function can change after conjugation. These factors should be reviewed before synthesis.

Cargo Size & Charge

Small molecules, peptides, proteins, ASOs, siRNA, and nanoparticles impose different steric and electrostatic constraints.

Attachment Site

N-terminal, C-terminal, lysine, cysteine, and unnatural-amino-acid handles can affect orientation and activity.

Spacer Architecture

Ahx, PEG, amino-acid spacers, and cleavable linkers can improve accessibility or enable release.

Sequence Format

Linear, cyclic, stapled, D-amino-acid, retro-inverso, and lipidated formats may change stability and uptake.

Solubility & Aggregation

Highly cationic or hydrophobic sequences may require formulation, counterion, or purification optimization.

Biological Model

Performance can differ across purified systems, cultured cells, organoids, and in vivo models.

Endosomal Release

Cell entry does not guarantee cytosolic delivery; an escape motif or cleavable design may be required.

Analytical Strategy

Mass confirmation, analytical HPLC, identity testing, and project-specific characterization should match complexity.

Related Capabilities

Supporting Peptide Engineering Services

Targeting and delivery sequences are frequently combined with complementary synthesis, modification, and analytical services.

Peptide Bioconjugation

Attachment to oligonucleotides, proteins, drugs, dyes, and materials.

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Reactive Handles

Azide, alkyne, DBCO, BCN, tetrazine, TCO, maleimide, and thiol.

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PEGylated Peptides

Discrete PEG spacers and polymer attachment for delivery constructs.

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Fluorescent Peptides

Reporter labeling for uptake, localization, and biodistribution studies.

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Cyclic Peptides

Conformationally constrained targeting ligands and receptor binders.

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Peptide Purification

Preparative HPLC matched to sequence and construct complexity.

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Analytical & Release QC

Mass confirmation, purity analysis, and advanced characterization.

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Custom Peptide Libraries

Variant libraries for sequence screening and delivery optimization.

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Scientific Consultation & Quote

Need Help Selecting a Targeting or Delivery Peptide?

Share the intended biological destination, cargo type, preferred attachment site, sequence requirements, scale, purity, and downstream assay. Our scientists can review sequence feasibility, linker architecture, conjugation route, purification risk, and analytical requirements before manufacturing begins.
Request a Quote Speak to a Scientist

Need help before quoting?

Email: info@biosyn.com
Phone: 800-227-0627 (US/CAN)
Phone: +001-972-420-8505 (INT)

Helpful Project Information

  • Peptide sequence or target peptide family
  • Biological destination or receptor
  • Cargo type and molecular size
  • Preferred conjugation site and linker
  • Other labels, lipids, or modifications
  • Required quantity, purity, and formulation
  • Relevant publication or catalog reference

How We Evaluate Your Design

We review sequence complexity, charge, hydrophobicity, attachment-site accessibility, linker length, orthogonal chemistry, purification feasibility, and project-specific QC. When a requested route is impractical, we explain the limitation and propose a scientifically sound alternative.

Quality Systems

Quality Systems & Manufacturing Support

QMS

Quality-Supported Targeting & Delivery Peptide Manufacturing

Targeting and delivery peptide projects are supported by controlled synthesis, complex modification, conjugation, preparative purification, analytical characterization, documentation, traceability, and project-specific packaging.

ISO 9001:2015 Quality-management system supporting controlled custom manufacturing and continual improvement. Learn more about quality systems
ISO 13485:2016 Quality-management practices supporting projects requiring enhanced documentation and traceability. Learn more about quality systems
ISO 14001 Environmental-management framework supporting responsible operational practices. Learn more about environmental management
Peptide Analytical QC Analytical HPLC or UPLC, LC-MS, optional advanced characterization, and project-specific release documentation.
Questions We Discuss with Researchers

Targeting & Delivery Peptide FAQ

FAQ

Can you synthesize D-amino-acid or retro-inverso variants?
Yes. D-amino-acid substitution, retro-inverso designs, terminal modifications, and other stability-enhancing formats can be evaluated.
Are the sequences on this page fixed?
No. They are representative starting points. Sequence truncation, substitution, cyclization, lipidation, spacer addition, and conjugation-site engineering can be customized.
Can a targeting peptide be combined with an endosomal escape peptide?
Yes. Multifunctional constructs can combine receptor targeting, cellular uptake, and endosomal escape, provided the architecture is designed to preserve each function.
How should the peptide be attached to the cargo?
The preferred site depends on the peptide mechanism and active region. N-terminal, C-terminal, lysine, cysteine, or unnatural-amino-acid handles can be used with direct, PEG, or cleavable linkers.
Can you make cyclic RGD and other constrained targeting peptides?
Yes. Disulfide-cyclized, head-to-tail, side-chain-cyclized, stapled, and other constrained architectures can be evaluated.
What QC is recommended?
Mass confirmation and analytical HPLC are standard starting points. Additional testing can be selected according to sequence complexity, cargo, intended use, and formulation.
What is the difference between a targeting peptide and a delivery peptide?
A targeting peptide recognizes a biological destination such as a receptor, tissue, or cell type. A delivery peptide promotes uptake, membrane interaction, intracellular transport, or cargo release. Some sequences perform both functions.
Can these peptides be conjugated to oligonucleotides or proteins?
Yes. They can be linked to ASOs, siRNA, proteins, dyes, drugs, lipids, nanoparticles, and other cargos using site-specific conjugation handles and linker systems.
More FAQ'sAll FAQ's
Scientific Background & Recommended Reading

Recommended Reading

Selected foundational and review articles covering cell-penetrating peptides, tumor-homing peptides, pH-responsive membrane insertion, blood–brain barrier shuttles, and intracellular delivery design.

  1. Guidotti G, Brambilla L, Rossi D. Cell-penetrating peptides: from basic research to clinics. Trends in Pharmacological Sciences. 2017;38:406–424.
  2. Sugahara KN, Teesalu T, Karmali PP, et al. Tissue-penetrating delivery of compounds and nanoparticles into tumors. Cancer Cell. 2009;16:510–520.
  3. Reshetnyak YK, Andreev OA, Lehnert U, Engelman DM. Translocation of molecules into cells by pH-dependent insertion of a transmembrane helix. Proceedings of the National Academy of Sciences USA. 2006;103:6460–6465.
  4. Demeule M, Régina A, Ché C, et al. Identification and design of peptides as a new drug delivery system for the brain. Journal of Pharmacology and Experimental Therapeutics. 2008;324:1064–1072.
  5. Wadia JS, Stan RV, Dowdy SF. Transducible TAT–HA fusogenic peptide enhances escape of TAT-fusion proteins after lipid raft macropinocytosis. Nature Medicine. 2004;10:310–315.
  6. Bio-Synthesis technical resource. Catalog Peptide Library for additional targeting, signaling, transport, and biologically active peptide sequences.

Scientific note: A published sequence is a starting point rather than a guarantee of equivalent performance after conjugation. Cargo identity, attachment site, linker architecture, formulation, and assay model can alter targeting, uptake, trafficking, and release.

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Greetings, Researchers,

Please be advised that any information, guidelines, write-ups, and oral/video/graphic content on our website are intended solely as general guidelines.
It is the researcher's sole responsibility to conduct thorough research on the design of products intended for their experiments before submitting
their designs to Biosynthesis for production feasibility review.
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